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diff --git a/77728-0.txt b/77728-0.txt new file mode 100644 index 0000000..793eb34 --- /dev/null +++ b/77728-0.txt @@ -0,0 +1,11095 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 77728 *** + + + Transcriber’s Notes + + Phrases and characters printed in blackletter, bold face and italics + in the source document have been transcribed between ~tildes~, =equal + signs= and _underscores_ respectively. Small capitals have been + replaced with ALL CAPITALS. + + More Transcriber’s Notes may be found at the end of this text. + + + + + ~The Rural Text-Book Series~ + EDITED BY L. H. BAILEY + + _Carleton_: THE SMALL GRAINS. + + _B. M. Duggar_: THE PHYSIOLOGY OF PLANT PRODUCTION. + + _J. F. Duggar_: SOUTHERN FIELD CROPS. + + _Fisk_: THE BOOK OF ICE-CREAM. + + _Gay_: BREEDS OF LIVE-STOCK. + + _Gay_: PRINCIPLES AND PRACTICE OF JUDGING LIVE-STOCK. + + _Goff_: PRINCIPLES OF PLANT CULTURE. + + _Guthrie_: THE BOOK OF BUTTER. + + _Harper_: ANIMAL HUSBANDRY FOR SCHOOLS. + + _Harris_ and _Stewart_: THE PRINCIPLES OF AGRONOMY. + + _Hitchcock_: TEXT-BOOK OF GRASSES. + + _Jeffery_: TEXT-BOOK OF LAND DRAINAGE. + + _Jordan_: FEEDING OF ANIMALS. REVISED. + + _Livingston_: FIELD CROP PRODUCTION. + + _Lyon_: SOILS AND FERTILIZERS. + + _Lyon_, _Fippin_ and _Buckman_: SOILS; THEIR PROPERTIES AND + MANAGEMENT. + + _Mann_: BEGINNINGS IN AGRICULTURE. + + _Montgomery_: THE CORN CROPS. + + _Morgan_: FIELD CROPS FOR THE COTTON-BELT. + + _Mumford_: THE BREEDING OF ANIMALS. + + _Piper_: FORAGE PLANTS AND THEIR CULTURE. + + _Sampson_: EFFECTIVE FARMING. + + _Thom_ and _Fisk_: THE BOOK OF CHEESE. + + _Warren_: ELEMENTS OF AGRICULTURE. + + _Warren_: FARM MANAGEMENT. + + _Wheeler_: MANURES AND FERTILIZERS. + + _White_: PRINCIPLES OF FLORICULTURE. + + _Widtsoe_: PRINCIPLES OF IRRIGATION PRACTICE. + + + + + THE + BOOK OF ICE-CREAM + + BY + WALTER W. FISK + + ASSISTANT PROFESSOR OF DAIRY INDUSTRY, NEW YORK + STATE COLLEGE OF AGRICULTURE AT + CORNELL UNIVERSITY + + + ~New York~ + THE MACMILLAN COMPANY + 1919 + + _All rights reserved_ + + + COPYRIGHT, 1919 + BY THE MACMILLAN COMPANY + Set up and electrotyped. Published November, 1919. + + + + +PREFACE + + +The older ones of us look back on the ice-cream of our youth as +a luxury, to be expected on festivals and holidays. The rising +generation, however, is coming to look on it as a food. Once the +manufacture of the confectionery shop and the household, it is now +produced in great quantities by concerns devoting themselves to it +entirely, making it by highly developed standardized processes. A +line of special machinery has been perfected for its manufacture. The +subject is taught in the colleges. Yet the home manufacture has not +passed and should not pass; rather should the product be made more +frequently and in larger quantity in the household. + +No longer must one offer an excuse for a book on ice-cream. This book +is made for class-room and laboratory use, growing out of the author’s +teaching experience; the manufacturer’s interest has been set forth; +yet it is hoped that the housewife will find directions for her use. + +Acknowledgment is due the following parties for valuable assistance +either for the illustrations, or definite information or helpful +criticisms: Henry Vogt Machine Co., Louisville, Ky.; Wheats Ice Cream +Co., Buffalo, N. Y.; DeLaval Separator Co., New York, N. Y.; Jamison +Cold Storage Door Co., Hagerstown, Md.; Merrell-Soule Co., Syracuse, +N. Y.; The Ekenberg Co., Cortland, N. Y.; Chapin-Sacks Mfg. Co., +Washington, D. C.; The Creamery Package Mfg. Co., Chicago, Ill.; +York Mfg. Co., York, Pa.; Davis-Watkins Dairymen’s Mfg. Co., Chicago +Ill.; J. G. Cherry Co., Cedar Rapids, Ia.; Emery Thompson Machine and +Supply Co., New York, N. Y.; T. D. Cutler, Ice-Cream Trade Journal, +New York, N. Y.; Brunswick Refrigerating Co., New Brunswick, N. J.; L. +O. Thayer, The International Confectioner, New York, N. Y.; Mojonnier +Bros., Chicago, Ill.; Sharples Separator Co., West Chester, Pa.; Joseph +Burnett Extract Co., Boston, Mass.; Nafis Glass Co., Chicago, Ill.; +J. E. Reyna, Dept. of Drawing, New York State College of Agriculture, +Ithaca, N. Y. The following members of the Dairy Dept. of the New York +State College of Agriculture at Cornell University, Ithaca, N. Y.: W. +A. Stocking, H. E. Ross, T. J. McInerney, W. E. Ayres, G. C. Dutton, H. +C. Troy, E. S. Guthrie, G. C. Supplee. + + W. W. FISK. + + ITHACA, N. Y., + _March 1, 1919_. + + + + +TABLE OF CONTENTS + +(Numbers in the text refer to paragraphs) + + + CHAPTER I + + PAGES + + GENERAL STATEMENTS ON ICE-CREAM 1-7 + Materials used in ice-cream, 1; Definition of ice-cream, 2; + Problems of ice-cream-making, 3; Ice-cream-making a science, 4. + + + CHAPTER II + + MILK AND CREAM AS RELATED TO ICE-CREAM 8-24 + + Method of securing supply, 5; Quality of milk and cream + desired, 6; Why milk and cream are not of the desired quality, + 7; The flavor of foods eaten by the cow, 8; The absorption of + flavors and odors in the atmosphere, 9; The unhealthy condition + of the cow, 10; The bacteria in the milk, 11; The sediment + test, 12; How to prevent the growth of micro-organisms in the + milk and cream, 13; Milk and cream production and handling, 14; + Clarifier, 15; The chemical composition of the milk and cream, + 16. + + + CHAPTER III + + MANUFACTURED MILK PRODUCTS AS RELATED TO ICE-CREAM 25-42 + + _Condensed and Evaporated Milk_: Method of manufacture, 17; + Standards for condensed milk, 18; Conditions essential for a + milk condensory, 19; Supply of condensed milk for the ice-cream + plant, 20. _Milk Powder_: Standards for milk powder, 21; + Powdered milk processes, 22; Merrell-Soule powdered milk, 23; + History of Merrell-Soule process, 24; Uses of Merrell-Soule + powder in ice-cream, 25; Ekenberg powdered milk, 26; Uses of + Ekenberg powder in ice-cream, 27; Butter, 28. + + + CHAPTER IV + + SUGAR, CHOCOLATE PRODUCTS, FRUITS, STABILIZERS AND FILLERS 43-56 + + Sugar, 29; Invert sugar, 30; Sugar-saving substitutes, 31; + Cocoa and cocoa products, 32; Manufacture of chocolate and + cocoa, 33; Composition of cocoa products, 34; Adulteration of + cocoa and standards of purity, 35; Chocolate sirup, 36; Fruits, + 37; Nuts, 38; Stabilizers and fillers, 39; Gelatine, 40; + Preparing gelatine for use in the ice-cream, 41; Gum + tragacanth, 42; Other substances used as binders, 43; Eggs, 44; + Starchy fillers, 45; Prepared ice-cream powders, 46; Rennet, + 47. + + + CHAPTER V + + FLAVORING EXTRACTS 57-68 + + _Vanilla Extract_: Nature of vanilla plant, 48; Curing vanilla + beans, 49; Marketing vanilla beans, 50; Production of vanilla + beans, 51; The ingredients of vanilla extract, 52; The + chemistry of vanilla, 53; Adulteration of vanilla extract, 54. + _Lemon Extract_: Preparation of lemon oil, 55; The chemistry of + lemon oil, 56; Orange extract, 57; Fruit extracts, 58. + + + CHAPTER VI + + CLASSIFICATION 69-80 + + Classification of ice-cream, 59; Receipts for ice-cream, 60; + Vanilla ice-cream, 61; Chocolate ice-cream, 62; Caramel + ice-cream, 63; Coffee ice-cream, 64; Maple ice-cream, 65; Fruit + ice-cream, 66; Nut ice-cream, 67; Bisque ice-cream, 68; Mousse, + 69; Cooked ice-cream, 70; Parfait, 71; Puddings, 72; Custards, + 73; Ices and sherbets, 74; Ices, 75; Water sherbets, 76; + Punches, 77; Milk sherbets, 78; Lacto, 79. + + + CHAPTER VII + + EQUIPMENT 81-100 + + Freezers, 80; Mixers, 81; Gelatine kettles, 82; Hardening the + ice-cream, 83; Packing-cans, 84; Ice crushers, 85; Ice-cream + can washers, 86; Emulsors, creamers, and homogenizers, 87; Cost + of equipment, 88. + + + CHAPTER VIII + + REFRIGERATION AS APPLIED TO ICE-CREAM-MAKING 101-128 + + Terms used, 89. _Natural Ice_: The ice field, 90; The + ice-house, 91; Harvesting and storing, 92; Amount of ice + needed, 93; Use of ice and salt mixture, 94. _Mechanical + Refrigeration_: Principles of mechanical refrigeration, 95; + Materials used in mechanical refrigerating systems, 96; + Operation of refrigerating machines, 97; The compression + system, 98; Parts of a compression system, 99; Operation of + direct expansion compression system, 100; Location of + evaporating coils, 101; Notes on operating compression system, + 102. _Absorption Systems_: Operation of absorption + refrigerating systems, 103; Arrangement of double pipe and + atmospheric absorption machines, 104. + + + CHAPTER IX + + PREPARING THE MIX 129-133 + + Importance of preparing the mix, 105; Usual procedure in + preparing the mix, 106; Temperature of the mix, 107. + + + CHAPTER X + + FREEZING PROCESS 134-144 + + Purpose of freezing, 108; Rate of freezing, 109; Proper method + of freezing, 110; Over-run or swell, 111; Condition of + ice-cream when removed from freezer, 112; Freezing sherbets and + ices, 113. + + + CHAPTER XI + + HARDENING ICE-CREAM 145-162 + + Methods of hardening, 114; Hardening in ice and salt mixture, + 115; The slush-box or brine-box method of hardening, 116; The + hardening-room, 117; The still-air type, 118; The gravity + air-type, 119; The forced-air type, 120; Defrosting the coils, + 121; Time required for hardening, 122; Effects of hardening on + quality, 123; Fancy molded ice-cream, 124. + + + CHAPTER XII + + JUDGING AND DEFECTS OF ICE-CREAM 163-169 + + Score-cards, 125; Explanation of characteristics mentioned in + score-card, 126; Defects in ice-cream, 127; Defects in flavor, + 128; Defects in body and texture, 129; Defects in richness, + 130; Defects in appearance, 131; Defects in package, 132. + + + CHAPTER XIII + + BACTERIA IN RELATION TO ICE-CREAM 170-182 + + Sources of bacteria in ice-cream, 133; The effect of freezing + and hardening on the bacterial count, 134; Types of organisms + in ice-cream, 135; The total-acid groups, 136; The inert group, + 137; The alkali group, 138; The peptonizing group, 139; Colon + Bacilli in ice-cream, 140; Difficulties in studying the + bacteriology of ice-cream, 141. + + + CHAPTER XIV + + TESTING 183-245 + + _The Babcock Test_: Testing whole milk for fat, 142; Composite + samples of milk, 143; Measuring the sample, 144; Adding the + acid, 145; Whirling the sample, 146; Reading the test, 147; + Appearance of a completed test, 148; Care of the test-bottles, + 149; Testing cream, 150; Cream testing apparatus, 151; Sampling + cream, 152; Making the cream test, 153; Tempering the fat and + reading the percentage, 154; Testing skim-milk, 155; + Modifications of the Babcock test for ice-cream, 156; The + glacial acetic and hydrochloric acid test, 157; The sulfuric + acid test, 158; Acetic and sulfuric acid test, 159; The + lactometer, 160; Calculating the solids not fat in the milk, + 161; Testing milk for acidity, 162; Test for formaldehyde, 163; + Test for boiled milk, 164. _Testing Butter for Fat, Moisture, + and Salt_: Preparing the sample, 165; Testing butter for fat, + 166; Testing butter for moisture, 167; Testing butter for salt, + 168; Test for viscosity, 169; Standardization, 170; Benkendorf + test for over-run in ice-cream, 171; Test to determine the + hardness of ice-cream, 172. _Mojonnier Tester_: General + preliminary information, 173; Testing evaporate, sweetened + condensed, bulk condensed milk, ice-cream (mix or melted) for + fat or total solids, 174; Fat determination, 175; Total solids + determination, 176; Testing butter, 177; Testing fresh milk, + skim-milk, whey, and buttermilk for fat and total solids, 178; + Testing powdered milk, cocoa, malted milk and milk chocolate + for fat and total solids, 179; Testing cream for fat and total + solids, 180; List of precautions to observe in operating + Mojonnier tester, 181. _Mojonnier Over-run Tester_: Adjusting + cups for mix, 182; Actual operation, 183; Controlling the + over-run, 184; Savings and economics, 185. + + + CHAPTER XV + + MARKETING AND BUSINESS MANAGEMENT 246-271 + + Demand for ice-cream, 186; Food value of ice-cream, 187; + Locating a market, 188; Method of delivery, 189; Cost of + delivery, 190; Packages used for delivery, 191; Advertising, + 192; Salesmen, 193. _Business Management_: Purchase of raw + material, 194; Price of dairy products, 195; Bookkeeping + system, 196; Shipping clerk, 197; Report blanks, 198; Losses, + 199; Pack-cans and tubs, 200; Rusty pack-cans, 201; Soft + ice-cream, 202; Transferring, 203. _Laws_: Sanitary conditions + and adulterated milk and cream, 204; Babcock test, 205; + Purchaser’s or vender’s license, 206; Legal standards, 207. + + + CHAPTER XVI + + CONSTRUCTION AND ARRANGEMENT OF THE FACTORY 272-286 + + Location of the plant, 208; Arrangement of machinery, 209; + Loading platform, 210; Light, 211; Ventilation, 212; Floors, + 213; Ceilings and side-walls, 214; Sinks and cupboards, 215; + Locker rooms, 216; Cleanliness, 217; Cleaning utensils, 218; + Cleaning the floor, 219; Store-room and work shop, 220; + Sanitary codes, 221. + + + CHAPTER XVII + + HISTORY AND EXTENT OF THE INDUSTRY 287-296 + + Early history, 222; Development of ice-cream in the household, + 223; Development of wholesale ice-cream, 224; Extent of the + industry, 225. + + + + +LIST OF ILLUSTRATIONS + + + PAGE + + FIG. 1.--Refrigerator room for storing cream and milk in a + large ice-cream plant. (Courtesy of Wheat’s Ice Cream Co., + Buffalo, N. Y.) 12 + + FIG. 2.--Filters from sediment tests showing the amount of + dirt in different samples of milk. These are the grades made by + the New York City Board of Health 18 + + FIG. 3.--Sharples milk clarifier 22 + + FIG. 4.--De Laval milk clarifier, turbine drive 22 + + FIG. 5.--View of modern condensory showing hot wells, vacuum + pan, vacuum pump and cooling tanks. (Courtesy of Wheat’s Ice + Cream Co., Buffalo, N. Y.) 26 + + FIG. 6.--Fruit storage in large ice-cream plant. (Courtesy of + Wheat’s Ice Cream Co., Buffalo, N. Y.) 51 + + FIG. 7.--Steam jacketed kettle for heating gelatine 53 + + FIG. 8.--Hand freezer with tub and can cut away showing ice and + salt mixture and beaters and scrapers in the can 82 + + FIG. 9.--Hand freezer with fly wheel, using salt and ice + mixture for freezing. The capacity of this freezer is five + gallons 82 + + FIG. 10.--Power driven tub and can freezer using a salt and ice + mixture. The can, dasher and gears are shown removed 82 + + FIG. 11.--Horizontal brine freezer attached to a salt and ice + brine box. The pump is behind the box 83 + + FIG. 12.--Vertical belt driven brine freezer connected to ice + and salt brine box. (Courtesy of Emery Thompson Machine and + Supply Co., New York City.) 84 + + FIG. 13.--Perfection brine freezer, direct motor drive. + (Courtesy of J. G. Cherry Co., Cedar Rapids, Iowa.) 85 + + FIG. 14.--Progress vertical belt drive brine freezer. (Courtesy + of Davis Watkins Dairymen’s Manufacturing Co., Chicago, Ill.) 86 + + FIG. 15.--Emery Thompson vertical direct motor drive brine + freezer. (Courtesy of Emery Thompson Machine and Supply Co., + New York City.) 87 + + FIG. 16.--Fort Atkinson belt drive brine freezer. (Courtesy of + Creamery Package Manufacturing Co., New York City.) 88 + + FIG. 17.--Disc brine freezer either continuous or batch. + (Courtesy of Creamery Package Manufacturing Co., New York + City.) 89 + + FIG. 18.--Side view of disc freezer shown in Fig. 17, showing + brine tank and pump. (Courtesy of Creamery Package + Manufacturing Company, New York City.) 89 + + FIG. 19.--Freezing discs of freezer shown in Figs. 17 and 18. + The scrapers for removing the frozen ice-cream from the discs + and the screw to force it out of the delivery spout are shown. + (Courtesy of Creamery Package Manufacturing Co., New York + City.) 90 + + FIG. 20.--A pasteurizer or ripener used as an ice-cream mixer. + Strips are attached to the coils to prevent the settling of the + sugar on the bottom 90 + + FIG. 21.--Minnetonna starter can or ice-cream mixer. (Courtesy + of Davis-Watkins Dairymen’s Manufacturing Co., Chicago, Ill.) 91 + + FIG. 22.--Alaska ice-cream mixer. The side is cut away showing + the coils and insulation. The mechanical agitator is seen at + the bottom. The cover fits air tight so that by means of an air + pump and air pressure the mix may be forced to the freezer. + (Courtesy of Creamery Package Manufacturing Co., New York + City.) 92 + + FIG. 23.--Wizard ice-cream mixer. (Courtesy of Creamery Package + Manufacturing Co., New York City.) 92 + + FIG. 24.--Emery Thompson ice-cream mixer. (Courtesy of Emery + Thompson Machine and Supply Co., New York City.) 92 + + FIG. 25.--Two types of ice-cream packing-cans 93 + + FIG. 26.--Ice spud 94 + + FIG. 27.--Ice cracker 94 + + FIG. 28.--Perforated ice shovel 94 + + FIG. 29.--Ice crusher with tight and loose pulley for + mechanical power. The teeth or picks on the drum may be seen 94 + + FIG. 30.--The perfection ice cream can washer and sterilizer. + (Courtesy of J. G. Cherry Co., Cedar Rapids, Iowa.) 94 + + FIG. 31.--Fort Atkinson ice-cream can washer and sterilizer. + (Courtesy of Creamery Package Manufacturing Co., New York + City.) 95 + + FIG. 32.--De Laval centrifugal emulsor. (Courtesy of De Laval + Separator Co., New York City.) 95 + + FIG. 33.--Perfection cream maker and emulsifier. (Courtesy of + J. G. Cherry Co., Cedar Rapids, Iowa.) 96 + + FIG. 34.--Progress homogenizer. (Courtesy of Davis-Watkins + Dairymen’s Manufacturing Co., Jersey City, N. J.) 97 + + FIG. 35.--Gaulin homogenizer. (Courtesy of Creamery Package + Manufacturing Co., New York City.) 98 + + FIG. 36.--Sharples centrifugal emulsor. (Courtesy of Sharples + Separator Co., West Chester, Pa.) 99 + + FIG. 37.--Hand ice-saw 106 + + FIG. 38.--Ice-plow with marker 106 + + FIG. 39.--Splitting fork 107 + + FIG. 40.--Approximate temperatures obtained with different + proportions of ice and salt 108 + + FIG. 41.--Refrigeration available with different percentages of + salt 109 + + FIG. 42.--Diagram showing relation of heat to temperature 113 + + FIG. 43.--Simplest compression system of refrigeration 116 + + FIG. 44.--Compression system of refrigeration in which the flow + of liquid is regulated by expansion valve and the liquid changes + to a gas in the coil of pipe thereby cooling the brine. The gas + then passes off into the atmosphere 117 + + FIG. 45.--Complete system of direct expansion refrigerating + system 118 + + FIG. 46.--Combination of direct expansion and brine storage + tanks. This is the same system as shown in Fig. 45 with the + brine tank (T) added in the refrigerator 120 + + FIG. 47.--Arrangement where it is desired to use cold brine for + cooling in some machine such as an ice-cream freezer. This is + the same refrigerating system as shown in Figs. 45 and 46 121 + + FIG. 48.--Diagram of the Vogt absorption refrigerating machine, + showing pipe connections and directions in which the liquids + and gases travel throughout the entire system. (Courtesy of + Henry Vogt Machine Co., Louisville, Kentucky.) 123 + + FIG. 49.--General arrangement of double pipe absorption + refrigerating machine, showing the connections and the + direction in which the liquids and gases flow. (Courtesy of + York Manufacturing Company, York, Pa.) 124 + + FIG. 50.--General arrangement of atmosphere absorption machine + showing the connections and the direction in which the liquids + and gases flow. (Courtesy of York Manufacturing Company, York, + Pa.) 126 + + FIG. 51.--Mixing room in large ice-cream plant. (Courtesy of + Wheat’s Ice Cream Company, Buffalo, N. Y.) 132 + + FIG. 52.--Battery of freezers in a large ice-cream plant. + (Courtesy of Chapin-Sacks Manufacturing Co., Washington, D. C.) 135 + + FIG. 53.--Different styles of transfer ladles or scoops 146 + + FIG. 54.--Plank box for hardening ice-cream in a salt and ice + mixture. The cans are placed in perforated cylinders so that + the cans may be changed and the ice will not fall in and fill + the space 147 + + FIG. 55.--Still-air hardening-room showing evaporating coils + forming shelves on which the pack-cans of ice-cream are placed + to harden. Other evaporating coils may be seen on the sides and + ceiling. (Courtesy of Brunswick Refrigerating Co., New + Brunswick, N. J.) 150 + + FIG. 56.--Forced air hardening-room. (Courtesy of Chapin-Sacks + Manufacturing Co., Washington, D. C.) 152 + + FIG. 57.--Brick ice-cream trowels. Straight and bent handles 158 + + FIG. 58.--Quart and sectional brick molds. The sectional bricks + hold several quarts 159 + + FIG. 59.--Brick hardening-room. (Courtesy of Chapin-Sacks + Manufacturing Co., Washington, D. C.) 160 + + FIG. 60.--Center mold and examples 161 + + FIG. 61.--Individual ice-cream molds and ice cave for packing + molds 161 + + FIG. 62.--Babcock milk pipette 185 + + FIG. 63.--Babcock whole milk test-bottle 186 + + FIG. 64.--Acid measure for Babcock test 187 + + FIG. 65.--Diagram showing the motion and position of a + test-bottle while mixing the milk and the acid 188 + + FIG. 66.--Hand and power centrifuges 189 + + FIG. 67.--Proper way to read the percentage of fat in a Babcock + whole milk test-bottle 191 + + FIG. 68.--Babcock cream test-bottles 193 + + FIG. 69.--Method of reading the percentage of fat in a Babcock + cream test-bottle 195 + + FIG. 70.--Skimmed-milk test-bottle 196 + + FIG. 71.--Quevenne lactometer 199 + + FIG. 72.--Board of Health lactometer 200 + + FIG. 73.--Nafis acid test 201 + + FIG. 74.--Apparatus for testing ice-cream over-run by the + Benkendorf method 213 + + FIG. 75.--Mojonnier tester for fat and total solids 217 + + FIG. 76.--Mojonnier over-run tester 241 + + FIG. 77.--Ice-cream packing tubs 252 + + FIG. 78.--Auto delivery truck for ice-cream 253 + + FIG. 79.--Ice-cream cabinet with side cut away showing + insulation and perforated cylinders on which the pack-cans of + ice-cream set 254 + + FIG. 80.--Different styles of ice-cream dishes 255 + + FIG. 81.--Shipping platform and office of shipping clerk in a + large ice-cream plant. (Courtesy of Wheat’s Ice Cream Co., + Buffalo, N. Y.) 261 + + FIG. 82.--Revolving door used for putting the ice-cream into + the hardening-room 263 + + FIG. 83.--Plan of a small ice-cream plant 273 + + FIG. 84.--Basement plan of large ice-cream plant 274 + + FIG. 85.--First floor plan of plant shown in Fig. 84 275 + + FIG. 86.--Second floor plan of plant shown in Figs. 84 and 85 275 + + FIG. 87.--A loading platform in a large ice-cream plant. + (Courtesy of Chapin-Sacks Manufacturing Co., Washington, D. C.) 276 + + FIG. 88.--The value of skylights is shown by the well-lighted + freezing-room, considerable floor space above being sacrificed + for this purpose. (Courtesy of Wheat’s Ice Cream Co., Buffalo, + N. Y.) 277 + + + + +THE BOOK OF ICE-CREAM + + + + +THE BOOK OF ICE-CREAM + + + + +CHAPTER I + +_GENERAL STATEMENTS ON ICE-CREAM_ + + +Ice-cream is known commonly to-day as a food, although in the past +it was considered and used only as a delicacy or dessert. Because of +the rapid growth of the industry and the large number and varying +amounts of materials that can be used in the making of ice-cream, its +composition may be varied within wide limits. The Federal Government +and most of the States have set standards for ice-cream. Some products, +such as custards, sherbets, ices and the like, are usually included +in the general discussion of ice-creams but technically should not be +classed with them. + + +=1. Materials used in ice-cream.=--The basis of ice-cream is some +dairy product or a combination of dairy products, such as milk, cream, +skim-milk, condensed milk, milk powder, homogenized or emulsified milk +or cream, and the like. These materials contain varying amounts of fat +and solids not fat, ranging from 0 to several per cent. Either one or +all may be used, as the manufacturer determines, to give the ice-cream +the desired amount of fat and milk solids. The price often determines +the kind and amounts of the different materials to be used. It is +important that these dairy products be clean; otherwise the ice-cream +may have an undesirable flavor. + +Sugar in some form must be used to sweeten ice-cream. Granulated sugar +was employed ordinarily before the war. However, in conserving for the +war, it was found that various sirups could be substituted. Corn sirup +was commonly used, and some invert sugar, maple sirup and honey in +smaller amounts. + +A large variety of materials may be utilized to flavor the ice-cream. +The extracts commonly employed are vanilla and lemon. Fruits, either +fresh, canned, preserved, dried or candied, may be used as flavoring, +various bread or cake products, such as macaroons, sweetened wafers and +sponge cake, and also caramel and chocolate products, usually chocolate +or cocoa. + +A little color of the proper shade to give the product the +characteristic tint suggested by the flavor is commonly added. + +If the ice-cream is not consumed as soon as it is made, ice crystals +soon separate, causing it to become grainy in texture. In order to +prevent this, some form of “stabilizer” is added, commonly gelatine. +However, gum tragacanth or some of the prepared ice-cream powders may +be used. + + +=2. Definition of ice-cream.=--Because of the large variation of +materials, both in quantity and kind, that may be used in its making, +the definitions of ice-cream are more or less elastic. The various +dictionaries give the following definitions: _Webster_,--“Ice-cream is +milk or cream sweetened, flavored, and congealed by a freezing mixture, +sometimes instead of cream the materials of a custard are used”; +_Century_,--“Ice-cream is a confection made by congealing variously +flavored cream or custard in a vessel surrounded with a freezing +mixture;” _Standard_,--“Ice-cream is cream, milk or custard sweetened +and flavored and frozen by a freezing mixture, being usually agitated +by a dasher in the process to make it of uniform consistency.” The +United States Department of Agriculture bases its definition[1] on the +composition of the finished ice-cream. Its definitions are as follows: + +Ice-cream is a frozen product made from cream and sugar with or without +a natural flavoring and contains not less than 14 per cent of milk-fat. + +Fruit ice-cream[1] is a frozen product made from cream, sugar and +sound, clean, mature fruits, and contains not less than 12 per cent of +milk-fat. + +Nut ice-cream[1] is a frozen product made from cream, sugar and sound +non-rancid nuts and contains not less than 12 per cent of milk-fat. + +[1] Office of the Secretary, U. S. Dept. Agr., Bul. 19, 1906. + +The National Association of Ice-Cream Manufacturers defines ice-cream +and the adulterated product as follows: That for the purpose of this +act ice-cream is hereby defined and standardized: + + _First_: Ice-cream is a frozen compound, varied as to kind and + proportion of ingredients within the limits established by custom and + usage. + + _Second_: Ice-cream consists chiefly of a sweetened and flavored + mixture of cream, or cream and milk, or milk, with or without added + milk-fat in the form of sound sweet butter or as contained in + condensed, evaporated or concentrated milk or in milk powder, and + with or without added milk solids not fat in the form of skim-milk + powder or as contained in milk powder or in condensed, evaporated or + concentrated skim-milk, or of a sweetened and flavored homogenized or + emulsified mixture of sound, sweet butter, milk powder or skim-milk + powder and water, with the addition of gelatine, vegetable gum, or + other wholesome stabilizer. + + _Third_: Standard ice-cream contains not less than eight (8) per + cent milk-fat and the content of milk-fat and milk solids not fat + combined shall not be less than eighteen (18) per cent except when + the ingredients of standard ice-cream include eggs, fruit or fruit + juice, cocoa or chocolate, cake, confections or nuts, such reduction + of the percentage of milk-fat and milk solids not fat as may be due + to the addition of such ingredients shall be allowed. + + _Fourth_: When ice-cream is sold or offered for sale without + designation of its kind, quality or grade on a label, brand, or tag + attached to the package or container, or, in case of removal from the + original package or container, by a notice conspicuously posted in + or at the place where such ice-cream is sold or offered for sale, it + shall be deemed that such ice-cream is sold or offered for sale as + of the grade of and for standard ice-cream, or better. That for the + purposes of this act ice-cream shall be deemed to be adulterated: + + (1) If in quality or grade it is lower than the professed standard of + quality or grade which it is sold or offered for sale. + + (2) If it contains any added poisonous or other added deleterious + ingredient which may render such ice-cream injurious to health. + + (3) If it contains any rancid or renovated or process butter, or any + fat or oil other than milk-fat and the fat or oil of contained eggs + or nuts and the fat or oil of substances used for flavoring purposes + only. + + (4) If it consists in whole or in part of any filthy or decomposed + substance which may render such ice-cream injurious to health, or is + otherwise so contaminated that such ice-cream is injurious to health. + +That for the purpose of this act ice-cream shall be deemed to be +misbranded: + + _First_: If the label, brand, tag or notice under which it is sold or + offered for sale is false or misleading in any particular as to the + kind, grade or quality or composition of such ice-cream; or if any + notice to the purchaser required by this act to be given is omitted. + + _Second_: If it is sold or offered for sale as the product of + one manufacturer when in reality it is the product of another + manufacturer: or if on the label, brand, tag or notice under which it + is sold or offered for sale there is any false statement concerning + the sanitary conditions under which such ice-cream is manufactured. + +So far the description of ice-cream has mentioned only the materials +to be used and in some cases the chemical composition in so far +as percentage of fat is concerned. It is evident that there is +considerable difference of opinion regarding the minimum percentage of +fat that the ice-cream should contain. It would seem that it might not +only be desirable to mention the materials which could be employed, but +also the percentage of fat and total solids or milk solids not fat, by +means of a sliding scale. In the description, no account is taken of +the bacterial-content of the ice-cream. The number of organisms may or +may not give an indication of the quality of the materials used and +the sanitary condition under which the manufacturing and handling is +done. When a bacterial standard for milk is universally recognized and +enforced, then a bacterial standard for ice-cream may be enforced. +It is to be desired that an adequate definition of ice-cream will be +forthcoming and that this definition will be enforced. This will do +much to improve the quality of the product. + + +=3. Problems of ice-cream-making.=--The successful making of ice-cream +calls for an understanding of the complex factors involved. These +factors are: The production and handling of the milk and the milk +products employed; the chemical and bacteriological composition of the +milk products; the various tests used, such as fat, acid, tests for +swell and the like; the blending of the flavors of the various products +to secure the characteristic flavor desired; the freezing process and +subsequent handling of the ice-cream; the construction and operation +of the machinery. A working knowledge of the combination of the above +factors is necessary to make ice-cream of uniform quality. After the +manufacture, the marketing of the product is a vital question and it +should receive constant attention and study. + + +=4. Ice-cream-making a science.=--Only recently has the making of +ice-cream been recognized as founded on science. This is probably +because in the past most of the ice-cream was made in small amounts +largely in the household, while now it is manufactured in large +quantities in commercial plants. + +In these large plants and in the agricultural colleges, considerable +attention has been paid recently to the making of ice-cream. No +description of the process can replace experience. Description of +appearance of the ice-cream and conditions during the making process, +in terms definite and clear enough to be readily understood by +beginners, has been found to be impossible. Certain principles and +essentials of practice can be presented, which form the foundation for +intelligent work. The more study given to the process, and the better +the underlying principles are understood, the further we will depart +from rule-of-thumb practice. + + + + +CHAPTER II + +_MILK AND CREAM AS RELATED TO ICE-CREAM_ + + +Several milk products are commonly used in ice-cream, namely: whole +and skimmed-milk, cream, condensed milk, evaporated milk, milk powder +and butter. These may be utilized singly or in combinations. The +most important characteristic of the milk products is their flavor +which should be clean and sweet; if not, it is likely to impart its +undesirable flavor to the ice-cream. Much might be written on the +production, care and composition of the milk and cream. Space will not +permit this, but the essential factors as related to ice-cream will be +discussed. + + +=5. Method of securing supply.=--The ice-cream industry offers an +entirely different problem from the other branches of the dairy +industry in relation to securing a supply of milk and cream. This is +due to the location. There are usually brokers or commission men who +are willing to handle butter, cheese, condensed milk and other dairy +products which are not comparatively as perishable as ice-cream. +Therefore, the butter, cheese, and condensed milk plants are located +where they can secure easily a supply of raw milk, which is in the +country. On the other hand, there are no brokers or commission men who +handle ice-cream; therefore, the ice-cream is sold directly to the +retailer or consumer. Because of the ease of delivery, the ice-cream +plant is located in the center of population, namely, the city or +village. It has not proved satisfactory, either from the view point of +quality or cost of production, to make the ice-cream near the supply in +the country and ship the finished product to the city. + +Due to the location of the ice-cream plant in the city, there are four +ways of securing the raw materials: + + 1. Buy milk and cream from dealer. + + 2. Operate creamery in country and get supply from it. + + 3. Use surplus from other dairy operations, and purchase necessary + balance. + + 4. Use of homogenized or emulsified milk and cream. + +Each ice-cream concern will have to decide, after carefully considering +all the factors, which method is best adapted for its use. Each has its +advantages and disadvantages. + + _Buying milk and cream from dealer._ + + Advantages: + + 1. No surplus to dispose of. + + 2. Minimizes labor in the ice-cream plant. + + 3. Requires less capital. + + Disadvantages: + + 1. Uncertainty of cream supply. + + 2. No control of quality. + + 3. Higher cost of cream. + + 4. No control of fat-content of cream. + + 5. Must have separate supply of condensed milk. + + 6. At mercy of cream dealer. + + 7. Difficult to dispose of any surplus. + + _Operating creamery in country and getting supply from it._ + + Advantages: + + 1. Certain of known supply. + + 2. Better control of quality. + + 3. Easy to dispose of any surplus. + + 4. Usually a cheaper supply. + + 5. Can secure cream of desired fat-content. + + 6. Can pay patrons better price for milk. + + 7. May make own supply of condensed milk. + + 8. More independent. + + Disadvantages: + + 1. Requires more capital. + + 2. Requires more labor. + + 3. Requires more management. + + 4. Must deal directly with the dairy-men. + + 5. Transportation. + + 6. Must find suitable location. + + _Using surplus from other dairy operations and purchasing necessary + balance._ + + Advantages: + + 1. Makes an outlet for surplus. + + 2. Economy of delivery. + + Disadvantages: + + 1. May make too large a business. + + 2. May not have necessary equipment, especially refrigerator. + + 3. May not be able to purchase necessary balance of supply. + Disadvantages same as buying from dealer. + + 4. If side line, may not give it proper attention. + + 5. May not have surplus only part of year so balance of year do not + care to operate. + + _Use of homogenized or emulsified milk and cream._ + + Advantages: + + 1. When big demand can quickly make supply of cream. + + 2. Sweet cream can be secured in localities where it can not be + produced easily, especially the South. + + 3. Does not necessitate carrying a large surplus of cream. + + 4. Usually a cheap supply of cream. + + Disadvantages: + + 1. Tendency to try to use butter and milk products of inferior + quality. + + 2. Because of the physical nature of homogenized cream, try to use + less fat in it. + + +=6. Quality of milk and cream desired.=--Regardless of how obtained, +the cream and milk should be of the desired quality for ice-cream +manufacture. The cream should be clean flavored and sweet. In some +plants, when the cream is slightly sour, a neutralizer is added, +but this practice should not be followed. Better care, better +holding methods or both should be employed to insure sweet cream. +The refrigerated room in which milk and cream are stored in a large +ice-cream plant is shown in Fig. 1. Cream for ice-cream-making should +not have more than 0.24 per cent of acid by the acid test. (For use +of acid test, see Chapter XIV.) In order to insure sweetness, cream +is usually pasteurized. Pasteurization[2] is heating to a temperature +sufficiently high, usually 145° F. and held at this temperature for +a sufficient period, usually thirty minutes, to kill most of the +organisms in the milk and then rapidly cooling to 50° F. or below. +When pasteurized cream and milk are used, there is not the danger +from disease organisms that there is from raw cream. An “aged” cream +is to be desired for ice-cream-making because it is more viscous. By +“aged” is meant the holding of the cream for a period after separating +before it is made into ice-cream. Usually it is aged for twenty-four to +thirty-six hours. While aging it must be kept cold so it will not sour +and it should not be frozen. It is hard to melt frozen cream and it is +liable to cause the ice-cream to be grainy. + +[2] Ayres, S. H., “The Present Status of the Pasteurization of Milk,” +U. S. Dept. Agr. Bul. 342, 1916. + +[Illustration: FIG. 1.--Refrigerated room for storing milk and cream in +a large ice-cream plant.] + +The demand for ice-cream fluctuates with the weather changes. When +it is hot there is an extensive demand but if the weather rapidly +becomes cool this demand suddenly decreases or _vice versa_. This means +that the ice-cream-maker either must carry or have at his disposal +a variable supply of cream. When hot weather increases the demand, +there may not be time to age the cream or it may be held so long that +it becomes sour. Homogenized or emulsified cream is to be desired for +ice-cream-making because it gives a smoother body and texture to the +product. This is undoubtedly due to the fat globules and other solids +being broken up into smaller particles by the process. + + +=7. Why milk and cream are not of the desired quality.=--Some milk and +cream has undesirable flavors which may be more or less pronounced. +These are due to: the flavor of foods eaten by the cow; the absorption +of flavors and odors from the atmosphere; the health of the cow; the +bacteria present. If not properly handled, the milk and cream will soon +become sour. + + +=8. The flavor of foods eaten by the cow.=--The presence of undesirable +flavors in the milk is due many times to the cows eating foods with +very pronounced flavors. Most common of these foods are onion, garlic, +turnips, cabbage, decayed ensilage, various pasture weeds, and the +like. The flavoring oils are volatile and so are able to pass easily +through all the tissues of the animal, and in a short time pass off +through the various excretory channels. During the time that the food +is undergoing digestion, these volatile oils are not only present in +the milk, but all the tissues of the animal. By the time the process +of digestion is completed, the volatile flavors will have passed +away largely. Therefore, if the time of milking and feeding are +properly regulated, a dairy-man may feed considerable quantities of +strong-flavored food, without any appreciable effect on the flavor of +the milk. To do this successfully, the cows should be fed immediately +before or after milking, preferably the latter. This allows time for +the digestive process to take place, during which time the volatile +substances will have passed away. While, if the milking occurred three +or four hours after feeding, these volatile substances would be present +in the milk and so flavor it. + +In the case of those plants which grow wild in the pasture and to which +the cows have continued access, it is much more difficult to overcome +the bad flavor in the milk. The only thing which can be done is to +allow the cows to pasture for a short time immediately after milking. +This will make it necessary to supplement the food of the pasture with +dry feed, or to have another pasture where these undesirable plants do +not grow. + + +=9. The absorption of flavors and odors in the atmosphere.=--Milk, +especially when warm, possesses a remarkable ability to absorb and +retain odors in the surrounding atmosphere. For this reason, the +milk should be exposed only in a surrounding of clean pure air. Some +of the common sources of these undesirable odors are: bad smelling +stables; unclean cows; aërating milk near hog pens, barnyards, swill +barrels, and like odoriferous sources; strong-smelling feeds in the +stable during milking, and the like. The only way to overcome these +undesirable flavors and odors in the milk is not to expose the milk to +them. The safest policy is to remove the source of the odor. + + +=10. The unhealthy condition of the cow.=--Milk secreted just before or +just after parturition is different in physical properties and chemical +composition from that secreted at any other time during the lactation +period. This milk is known as colostrum. It is considered unfit for +human food, either as milk or products manufactured from the milk. Most +states consider colostrum adulterated milk, and prohibit its sale +fifteen days before or five days after parturition.[3] + +[3] N. J. Agricultural Law, 1913, section 30; Mich. Agricultural Law, +1915, section 77; Wis. Agricultural Law, 1913, section 4601-49-5. + +Whenever disease manifests itself in the cow, the milk should be +discarded at once as human food. Some diseases are common both to the +cow and man, such as tuberculosis and foot-and-mouth disease. If such +diseases are present in the cow, the milk acts as a carrier for them +to man. Digestive disorders of any sort in the cow are frequently +accompanied by undesirable flavors in the milk. These are not believed +to be due to the food eaten, but to the bad condition of the animal. On +resuming a normal condition, these undesirable flavors disappear. This +is especially noticeable when cows are turned out to pasture for the +first time in the spring, or when they are pastured on rank fall feed, +such as second-growth clover. + + +=11. The bacteria in the milk.=--The bacteria are microscopic +unicellular plants without chlorophyll. Besides bacteria, there are +other forms of the lowest orders of the vegetable kingdom found +in milk, such as yeasts and molds. The general characteristics of +yeast and bacteria are somewhat similar. Bacteria are very widely +distributed throughout nature. They are so small that they may float +easily in the air or on particles of dust. They are so resistant to +adverse conditions of growth that they may be present in a dormant +or spore stage, and thereby not be recognized readily; when suitable +environments for growth are again produced, germination takes place at +once. They are found in all surface water, on the surface of the earth, +and upon all organic matter. There are a great many different groups +of bacteria, some beneficial and some harmful to man. As they are so +small, it is difficult to differentiate between the beneficial and +harmful groups, except by the results produced or by a careful study +in an especially equipped laboratory. Bacteria have many forms, the +three common forms being: spherical (coccus); rod-like or cylindrical +(bacillus); and corkscrew (spirillum). The bacteria reproduce very +rapidly by fission, that is, a transverse partition forms in the cell +and when this partition is completed, the cell is divided. There are +then two bacteria where there was but one before. In some cases, this +division has taken place regularly in twenty to thirty minutes. Like +other plants, they are very sensitive to a food supply, to temperature, +and to moisture, as conditions of growth. Inasmuch as the bacteria are +plant cells, they must imbibe their food from materials in solution. +They may live on solid substances, but the food elements must be +rendered soluble before they can be utilized. Bacteria prefer a neutral +or slightly acid medium for growth, rather than an alkaline reaction; +however, there are many exceptions to this. The food for bacteria +must contain carbon, hydrogen, oxygen, and nitrogen, together with +small amounts of mineral matters. Organic compounds make available +food supplies. Ordinary milk furnishes a very favorable medium for +the growth of bacteria because it contains an adequate and easily +available food supply. In milk, there are certain groups of bacteria, +which are ordinarily present, but any others which happen to get into +the milk will live and rapidly multiply. Most forms of bacteria are +dependent on temperature as a condition of growth. There is a range +of temperature, more or less wide, at which the bacteria will grow +and multiply with the greatest rapidity. This is called the optimum +temperature and varies with the different groups of bacteria, but for +most it is between 75° F. and 95° F. Growth of most of the bacteria +found in milk will take place between 40° F.-45° F. to 105° F.-115° F. +Above and below these temperatures growth is retarded, and, if carried +to extremes, life will be destroyed. Like plants which form structures +called seeds to carry them through conditions unfavorable to growth, +so some groups of bacteria form spores. The spores are exceedingly +resistant to unfavorable conditions of growth, such as heat, cold, +drying, food supply, and even chemical agents. It is this property +which makes it difficult to destroy some bacteria. + +Because of the harmful effect of the micro-organisms in the milk and +cream, precautions should be taken to keep them out. If they do enter, +their growth can be checked by keeping the milk and cream cold. What +has been said regarding bacteria is true of molds and yeasts. + + +=12. The sediment test.=--The amount of solid material or dirt in +the milk is an indication of the amount of bacterial contamination. +It should be remembered that the strainer will take out the solid +material, but the soluble portion and the bacteria will be left in the +milk or cream. Thus an efficient strainer will defeat the sediment +test. There are several sediment tests on the market. The test consists +of filtering about a pint of milk through a cotton disc filter about +an inch in diameter. The solid material or dirt is left on the filter. +(Fig. 2.) The amount of dirt would indicate the amount of contamination +in the milk. Much improvement in the quality of the milk has been +accomplished by the use of the sediment test, because the cotton discs +with the dirt are posted where each patron can see them and pride +causes the careless dairy-man to take more pains in the care and +handling of his milk. + +[Illustration: + + 1 2 3 4 5 + CLEAN FAIRLY CLEAN MODERATELY CLEAN DIRTY FILTHY + +FIG. 2.--Filters from sediment tests showing the amount of dirt in +different samples of milk. These are the grades made by the New York +City Board of Health.] + + +=13. How to prevent the growth of micro-organisms in the milk and +cream.=--Next in importance to clean production in the care of milk +and cream, is the prevention of growth or development of the organisms +in it. This is accomplished by cooling and keeping the milk and cream +cold and covered. If they are produced clean and kept covered, there +are certain to be some micro-organisms in the milk and unless cooled +these will develop and quickly spoil the milk and cream. Ross[4] and +McInerney give the following summary regarding the cooling of milk and +cream: + +[4] Ross, H. E., and McInerney, T. J., “Cooling milk,” Cornell Reading +Courses, Vol. V, No. 102, 1914. + +“Milk becomes cool, of course, when it gives up its heat to some +substance colder than itself, and in order to have a rapid exchange +of temperatures between two substances it is necessary that they have +approximately the same density. On account of the great difference +in density between air and milk, the latter will cool very slowly +in air even though the temperature of the air is rather low. If milk +is allowed to cool by standing in a cold atmosphere, it will do so +unevenly, and by the time the milk in the center of the can is cooled, +that part near the walls of the can may be frozen. The fat is not +evenly distributed in frozen milk; therefore it is not so good as +normal milk. + +“1. The bacteria-content of milk held at a temperature of 50° F. +increases slowly, while the bacteria-content of milk held at 90° F. +increases rapidly. + +“2. At a temperature of 90° F. bacteria increase rapidly in milk that +had either a small or a large amount of bacteria in it originally. + +“3. Cooling milk by placing the cans in a tank of ice water is a +practical method for use in farm dairies. To cool the milk rapidly it +must be stirred at frequent intervals. + +“4. Stirring the milk at intervals of five minutes caused a +sufficiently rapid drop in temperature. Rapidity of cooling due to +stirring the milk at intervals of five minutes and at intervals of ten +minutes was very slight. + +“5. When sufficient quantities of ice were used, stirring the water in +the cooling tank had little effect on the rapidity of cooling. + +“6. In order to obtain the best efficiency from the conical type of +cooler, it is absolutely necessary to stir the water inside the cooler. + +“7. Lower temperatures can be obtained by using brine and ice than with +ice water alone.” + +Stocking[5] shows the effect of temperature on the development of the +bacteria in milk by the following experiment: A sample of milk, which +was thoroughly mixed, was divided into six equal parts. The six bottles +were placed in water at different temperatures for twelve hours, at +which time the germ-content of each lot was determined. The six bottles +were then all placed together in a temperature of 70 degrees and +allowed to remain until they curdled. As each sample curdled, the time +was recorded. The difference in the germ-content and the keeping time +is the result of the difference in temperature for a period of twelve +hours only, and shows what may happen easily in milk which is allowed +to stand overnight without thorough cooling. + +[5] Stocking, W. A., Jr., “Problems of the milk producers,” N. Y. State +Dept. Agr., Circ. 10, 1910. + +TABLE I + + Effect of different temperatures for twelve hours on the growth of + bacteria and on the keeping quality of milk + + I II + Kept at 45 degrees Kept at 50 degrees + Number of bacteria 9,300 Number of bacteria 18,000 + Curdled in 75 hours Curdled in 72 hours + + III IV + Kept at 55 degrees Kept at 60 degrees + Number of bacteria 38,000 Number of bacteria 453,000 + Curdled in 49 hours Curdled in 43 hours + + V VI + Kept at 70 degrees Kept at 80 degrees + Number of bacteria 8,800,000 Number of bacteria 55,300,000 + Curdled in 32 hours Curdled in 28 hours + + +=14. Milk and cream production and handling.=--The following diagram +shows the main sources of contamination and the undesirable methods of +handling by which the quality of milk and cream is impaired: + +Sources of contamination and undesirable methods of handling + + { Atmosphere in the stable { Dust from feed + { { Dust from floor and bedding + { + { Cows { Exterior of udder and flank + { { Coat + { + { Utensils { Dirty utensils + On the farm { { Rusty utensils + { + { { Dirty clothes + { Milker { Dirty hands + { { Wetting the teats + { + { Cooling { Air and dust + { { Dirty utensils + + Transportation from { Exposed to sun and dust + farm to creamery { Carried in dirty utensils + + { { Allowing milk to stand before separating + { { Allowing cream after separated to stand + { Careless methods { before cooling + Creamery { { Not cooling cream to low enough + { { temperature + { + { Dirty equipment + + { Use of dirty rusted cars. Allowing to stand on + Transportation from { railroad platforms, in the sun uncovered + creamery to ice-cream { Lack of can jackets + manufacturer { Poor delivery service + { Lack of refrigerator cars + { Too long shipments + + { Holding cream too long + Ice-cream manufacturer { Lack of refrigerator space to hold cream + { Dirty equipment and utensils + +The above shows that the producer controls most of the factors which +concern the sources of initial contamination.[6] After the milk leaves +the producer, if it is not properly handled, the organisms in it may +develop or if exposed to dirty conditions more contamination may take +place. The important factors in the production and handling of milk +are: clean utensils, clean healthy cows, small-top milk-pails, proper +cooling and maintaining of low temperature, 50° F. or below. The +importance of can jackets to aid in keeping the cream cold should not +be overlooked, especially when shipping in hot weather. The quality of +the milk and cream is largely determined by the time it is delivered at +the ice-cream plant. + +[6] Ayres, S. H., Cook, L. B., Clemner, P. W., “The four essential +factors in the production of milk of low bacterial content,” U. S. +Dept. Agr., Bul. 642, 1918. + +[Illustration: FIG. 3.--Sharples milk clarifier.] + +[Illustration: FIG. 4.--De Laval milk clarifier turbine drive.] + + +=15. Clarifier.=--If solid or semi-solid dirt either visible or +invisible is in the milk, it can be removed by the use of a clarifier. +This is a specially devised machine (Figs. 3 and 4) which takes out the +dirt by centrifugal force. It is desirable to clarify milk and cream +for ice-cream-making. Besides removing dirt which gets into the milk +during handling, the clarifier also takes out blood corpuscles and pus +cells which are sometimes secreted with the milk. + + +=16. The chemical composition of the milk and cream.=--It is not +possible here to discuss in detail the composition of the milk and +cream and the factors influencing it. Ross[7] gives the composition of +milk, cream and skimmed-milk as follows: + +[7] Ross, H. E., “Composition of milk and some of its products,” +Cornell Reading Course, Vol. 11, No. 32, 1913. + +TABLE II + +Showing composition of milk + + _Average_ _Maximum_ _Minimum_ + Water 87.0 90.69 80.32 + Sugar 5.0 6.03 2.11 + Fat 4.0 6.47 1.67 + Casein 2.6 4.23 1.79 + Albumen 0.7 1.44 .25 + Ash 0.7 1.21 .35 + +TABLE III + +Showing composition of cream + + _Cream high in fat_ _Cream low in fat_ + Water 29.0 76.6 + Fat 67.5 15.2 + Casein } 1.2 3.1 + Albumen} + Sugar 2.2 4.5 + Ash 0.1 0.6 + +TABLE IV + +Showing composition of skimmed-milk + + Water 90.60 + Fat .10 + Sugar 4.95 + Casein 3.15 + Albumen .42 + Ash .78 + +From the view point of the ice-cream-maker, the fat and solids not +fat are of special consideration. Each state has standards for milk, +cream and skimmed-milk. (See Table XV.) The federal standards[8] are +as follows: Milk is the fresh clean, lacteal secretion obtained by the +complete milking of one or more healthy cows, properly fed and kept, +excluding that obtained within fifteen days before and ten days after +calving and contains not less than eight and one-half (8.5) per cent of +solids not fat and not less than three and one-quarter (3.25) per cent +of milk-fat. + +[8] Office of the secretary, U. S. Dept. Agr., Circ. 19, 1906. + +Skim-milk is milk from which a part or all of the cream has been +removed, and contains not less than nine and one-quarter (9.25) per +cent of milk solids. Cream is that portion of milk, rich in milk-fat, +which rises to the surface of milk on standing, or is separated from +it by centrifugal force, is fresh and clean and contains not less than +eighteen (18) per cent of milk-fat. + +Milk and cream should be purchased on the fat test and not by measure, +the price being based on the fat-content. For method of testing, see +Chapter XIV. + +Because of the variable composition of milk and cream, it is necessary +to standardize them for use in ice-cream-making. For method of +standardization, see Chapter XIV. + + + + +CHAPTER III + +_MANUFACTURED MILK PRODUCTS AS RELATED TO ICE-CREAM_ + + +Besides the milk and cream, several other manufactured milk products +are used in ice-cream. What has been said previously about the milk +and cream applies also to the milk for these products. The quality, +especially the flavor, is very important. + + +CONDENSED AND EVAPORATED MILK + +There is a difference between condensed and evaporated milk, but +because of their similarity, both in composition and manufacture, they +will be considered together. Condensed milk usually has sugar added to +preserve it, although some ice-cream-makers use it without added sugar, +when it is known as plain in contrast to sweetened condensed milk. The +evaporated milk is usually sterilized in sealed cans to preserve it, no +sugar being added. More condensed milk is employed in making ice-cream +than evaporated milk. The condensed is usually shipped to the ice-cream +manufacturer in bulk, either in milk-cans or barrels. + + +=17. Method of manufacture.=--The water is removed from the milk by +heating under reduced pressure. The heating is usually done in a copper +pan. (Fig. 5.) This is accomplished by means of a steam jacket on the +bottom and usually one or two steam coils in the pan. Before drawing +the milk into the pan, it is heated in an open copper vessel, by +turning direct steam into the milk. This container is called the hot +well or fore warmer. The temperature varies according to whether plain +or sweetened condensed is being made. The sweetened is heated higher to +dissolve the sugar. The object of heating under reduced pressure is to +reduce the boiling point. At ordinary pressure milk would boil at the +same temperature or a little above that of water. At this temperature +the milk could not be condensed without imparting a pronounced cooked +flavor and caramelizing a part of the sugar. + +[Illustration: FIG. 5.--View of modern condensory showing hot wells, +vacuum pan, vacuum pump and cooling tanks.] + +The vacuum in the pan is produced by means of a vacuum pump. A vacuum +equal to a column of mercury about 25 inches is usually maintained. The +condenser is located at the top of the pan and is directly connected +with it. As the milk boils, the vapor passes from the pan into the +condenser. In the latter the vapor comes in contact with a spray of +cold water which causes it to condense. The pump carries off the +condensing water and the condensed vapor. When the desired density +is reached, the milk is drawn from the pan and cooled. The proper +concentration of the milk is determined by a special graduated scale +known as the Baumé. A more recent method is an electric resistance. +If sweetened condensed is being made, the sugar is added to the milk, +the mixture of sugar and milk are heated to dissolve the sugar before +drawing them into the pan. + +Sometimes the milk is superheated; this consists of turning live steam +into the milk just at the time that the desired concentration is +reached. It gives the condensed milk more of a “livery” appearance, +which is probably due to the precipitation of the albumen. + +The length of time required for condensing the milk to the desired +consistency varies with the amount of milk in the pan, amount of +heating surface, size and capacity of vacuum pump, and amount and +temperature of water in the condenser. + + +=18. Standards for condensed milk.=--The following standards are given +by the United States Department of Agriculture:[9] + +[9] Office of the Secretary, U. S. Dept. Agr., Food Inspection, +Decision 170, 1917. + +“Sweetened condensed milk, sweetened evaporated milk, sweetened +concentrated milk, is the product resulting from the evaporation of +a considerable portion of the water from the whole, fresh, clean, +lacteal secretion obtained by the complete milking of one or more +healthy cows, properly fed and kept, excluding that obtained within +fifteen days before and ten days after calving, to which sugar +(sucrose) has been added. It contains, all tolerances being allowed +for, not less than twenty-eight per cent (28.0 per cent) of total milk +solids, and not less than eight per cent (8.0 per cent) of milk fat. + +“Condensed skimmed milk, evaporated skimmed milk, concentrated skimmed +milk, is the product resulting from the evaporation of a considerable +portion of the water from skimmed milk, and contains, all tolerances +being allowed for, not less than twenty per cent (20.0 per cent) of +milk solids. + +“Sweetened condensed skimmed milk, sweetened evaporated skimmed milk, +sweetened concentrated skimmed milk, is the product resulting from the +evaporation of a considerable portion of the water from skimmed milk to +which sugar (sucrose) has been added. It contains, all tolerances being +allowed for, not less than twenty-eight per cent (28.0 per cent) of +milk solids.” + +Condensed or evaporated milk should be purchased only on its +composition, both fat and solids not fat. For method of testing, see +Chapter XIV. + + +=19. Conditions essential for a milk condensory.=[10]--“First. The +plant should be located in a community which is not only thoroughly +adapted in every way to a high standard of extensive dairy farming, +but is already far advanced in such development. The herds of cows +should be large, healthy, well cared for, and of a breed or breeds that +produce a grade of milk reasonably adapted for condensing purposes and +the production of a standard product. + +[10] These conditions are taken from the U. S. Dept. Agr., Weekly News +Letter, Vol. II, No. 45. + +“Second. In establishing a plant for condensing milk by the vacuum +process it is of primary importance that the location provide an +abundant, steady supply of pure, cold water, independent of the supply +required for boiler use. The quantity of water required to condense +a given quantity of milk will, of course, vary with the operating +conditions, such, for example, as the temperature of the condensing +water and the temperature (or the pressure) of the vapor to be +condensed. A general idea of the importance of water supply can be +obtained from the authoritative estimate that about 3 gallons of water +are required for the condensing of one pound of fresh milk (about one +pint). Difficulty in obtaining an adequate supply of good, pure, cold +water is a cause of serious embarrassment to some of the commercial +condensories now established, and the lack of it has been the cause of +many failures. + +“Third. An abundant supply of milk is an absolute necessity. The +exact quantity required daily will, of course, vary with the size of +the plant. Several reliable authorities have estimated that for the +profitable production of condensed milk on a commercial scale the +supply of raw milk to the factory should not fall below 15,000 pounds +a day. This estimate is exclusive of the daily supply of milk normally +required for other purposes by the community. Furthermore, if the +finished product is to be of marketable quality, the milk received at +the condensory must be of exceptionally high grade; that is, clean and +pure. While first-class milk is essential for the manufacture of a +first-class dairy product of any kind, it is absolutely necessary if a +condensed milk factory is to be a success. If a few cans of low-grade +milk are not detected at the receiving platform of a condensory, +the slight defects in the raw milk are multiplied in the process of +condensing it, and the result is practically certain to be the complete +loss of the whole batch, which may represent a financial loss of +several hundred dollars. This statement may be illustrated concretely: +It is claimed by authorities that raw milk containing as much as 0.2 +per cent acid (calculated as lactic acid) is not fit for condensing +purposes. This does not necessarily mean that it would taste sour, but +if accepted and condensed in the ratio of 2.25 to 1 (it may be more but +is seldom less), the acidity, increasing in the same ratio, would reach +0.45 per cent, which would be practically certain to cause a sour taste +in the finished product. Every housewife knows that sour milk will +coagulate or curdle on heating, and that the higher the temperature +the more rapid is the curdling process and the finer the curd. This +makes it unfit for cooking purposes. In the commercial production of +evaporated milk, the product must be sterilized in the cans at a very +high temperature in order to insure a good keeping quality. It is +obvious, therefore, that if milk is delivered to the factory with a +slight excess of acidity, it would probably be impossible to sterilize +the product obtained from it without producing a hard curd, which would +make the product absolutely unsalable, and thus a total loss to the +manufacturer. Furthermore, excessive acidity, which is principally +caused by improper care and handling of the milk, is not the only +condition that may render milk unfit for condensing. Other undesirable +qualities of the milk may also be induced by poor health and improper +care of the cows, by the kind and the condition of their feed, and by +many other details of imperfect management of the dairy farms. + +“The services of experts thoroughly qualified by training and long +experience in this particular line will be required to detect and guard +against these unfavorable conditions. + +“Fourth. Adequate facilities for marketing constitute another essential +to the commercial success of a condensed milk plant. Commercial +success, of course, implies a profitable market for the product--a +market which is readily and directly accessible to the plant without +adding excessively to the cost of manufacture, either in the form of +high freight rates or long hauls from the condensory to a railroad. +As already indicated, the successful manufacture of condensed milk on +a commercial scale requires a large output of the finished product--a +very much larger output than is likely to be consumed in the local +market; therefore, in selecting a location, favorable transportation +facilities to a good market or markets are a consideration of vital +importance to ultimate success. + +“Fifth. In establishing and operating a condensory, the necessity of +adequate capital is another important question. The cost of buildings +and equipment will, of course, vary with the purchase of superior or +inferior materials and workmanship, as well as size of the plant, and, +in some measure, the kind of condensed milk to be produced. In any +case, however, the buildings should be thoroughly substantial, more +so than is commonly considered necessary for a creamery or a cheese +factory. The major part of the equipment is a very highly specialized, +more or less complicated, and very expensive type. The proper operation +of the equipment, especially the vacuum pan, and the sterilizer when +the product is sterilized in cans, calls for a high degree of skill +and large experience, if serious losses are to be avoided and a +standardized legal product is to be produced. The cost of buildings, +equipment, and operation of a plant for the manufacture of evaporated +milk (unsweetened condensed milk for household use) will illustrate the +capital required for the manufacture of any other form of condensed +milk. Some reliable authorities have conservatively estimated that +adequate buildings and equipment for a minimum production on a +commercial scale would cost in the neighborhood of $25,000, exclusive +of working capital. The markets for condensed milk at best are very +unstable. Frequently, the manufactured product must be held several +months before it is marketed. In the meantime, the plant must be kept +in operation, for which a very considerable surplus capital must be +provided. The same authorities estimate this item at $10,000. It +therefore appears that in establishing and operating a milk condensory, +capital to the amount of at least $35,000 must be provided. That this +estimate is conservative is indicated by the fact that manufacturers +of condensed milk have stated that a capital of $50,000 is usually +necessary to operate a condensed milk factory. + +“Sixth. Commercial success in any manufacturing enterprise usually +requires much more than merely placing the product upon the market. A +demand for the product must be firmly established and a regular trade +developed before success is assured. To attain such a result the new +product must meet the keen competition of similar products already +well established. There are many well-established brands of condensed +milk now on the market. There may be room for many more, but new +brands, regardless of their quality, must expect to overcome strong +competition before a firm foothold is gained. This usually requires +extensive advertising and a competent, vigorous sales force, which +entails a heavy expense. Good salesmanship and advertising must be +continued. The necessity of a thoroughly organized selling organization +should, therefore, not be overlooked.” + + +=20. Supply of condensed milk for the ice-cream plant.=--From the above +conditions essential for a condensory, it is evident that an ice-cream +plant would not be justified in trying to operate one, unless also they +maintained a large milk and cream receiving plant in the country. It +is the usual practice for the ice-cream manufacturer to purchase the +supply of condensed milk. However, some plants have a condensory in +connection with their country plant, which is operated successfully. +When the supply of condensed milk is purchased, the basis of payment +should be the composition. For the methods of testing condensed milk, +see Chapter XIV. + + +MILK POWDER + +In certain localities, especially the South where it is hard to +secure milk and cream, milk powder and butter are often emulsified or +homogenized to make cream. Milk powder is also employed in the same +way to meet sudden demands for cream. Milk powder is often used in +ice-cream to increase the milk solids not fat and thereby give a firmer +body and a smoother texture. The composition varies in fat from skim to +whole milk. + + +=21. Standards for milk powder.=--The following standards are given by +the United States Department of Agriculture:[11] + +[11] Office of the Secretary, U. S. Dept. Agr., Food Inspection +Decision 170, 1917. + +“Dried milk is the product resulting from the removal of water from +milk, and contains, all tolerances being allowed for, not less than +twenty-six per cent (26.0 per cent) of milk fat, and not more than five +per cent (5.0 per cent) of moisture. + +“Dried skimmed milk is the product resulting from the removal of water +from skimmed milk and contains, all tolerances being allowed for, not +more than five per cent (5.0 per cent) of moisture.” + + +=22. Powdered milk processes.=--Two patented processes of making +powdered milk are in general use in this country at the present time, +the Merrell-Soule and the Ekenberg. + + +=23. Merrell-Soule powdered milk.=[12]--“The desired process must, it +was evident, be one which would not affect the active principles or the +nutritive qualities of milk, nor change its chemical reactions in any +way. The product when reaching the consumer must be, in every essential +quality, fresh milk. + +[12] This article is taken from the publication, “Merrell-Soule +Powdered Milk for the Dairy, Creamery and Ice Cream Plant,” +Merrell-Soule Co., Syracuse, N. Y., 1918. + +“The methods known as condensation and evaporation, also the earlier +milk powder processes, were efforts to achieve the desired result. But +in none of them was the goal completely attained, as it is to-day in +Merrell-Soule Powdered Milk--the product of a perfected process. + +“Liquid Milk is seven-eighths water. Merrell-Soule Powdered Milk +contains approximately 2 per cent of moisture. Transportation cost is +thus reduced to a very small percentage of the expense of shipping +liquid milk. The fact that powdered milk may be shipped by freight, +while liquid milk must go by express or baggage, means an additional +saving. + +“The expense of shipping powdered milk is also, of course, much lower +than the transportation cost of the condensed product. + +“The Merrell-Soule process reduces the bacteria count to a remarkably +low figure, and it is a demonstrated fact that the bacteria which are +to be found in the fresh-made powder tend to die off, rather than +propagate, during storage. + +“Merrell-Soule Powdered Milk is quickly and easily dissolved in water, +and the ‘reconstituted’ liquid milk thus obtained is pure, fresh milk, +with the delicate odor and unmistakable flavor of fresh milk, and with +every chemical reaction and nutritive property of fresh milk retained +unchanged.” + + +=24. History of Merrell-Soule process.=--“The history of powdered milk +dates back to the middle of the last century, when an inventor named +Grimwade patented, in England, the first commercially usable process. + +“He added carbonate of soda to fresh milk, evaporated it in +open-jacketed pans, with constant agitation, until a dough-like +substance resulted; added cane sugar, pressed the mixture between +rollers into ribbons, dried it still further, then pulverized it. + +“This process, cumbersome and unsatisfactory as it must have been, was +in practice for some years. Other processes followed at intervals for +half a century, but the real commercial development of the industry +dates back only about twenty years. + +“It was in 1899 that a machine for the drying of milk by what has since +become known as the ‘double roll’ process was invented by W. B. Gere, +since deceased, then secretary of the Merrell-Soule Co., and I. S. +Merrell, first vice president of the company. But the ‘dry milk’ which +resulted from this process was not satisfactory, and for that reason +was not put on the market by the Merrell-Soule Company. + +“Several other processes were then tried out, but none proved +satisfactory until Lewis C. Merrell, brother of I. S. Merrell, hit upon +the spraying of milk into a regulated current of heated air. This gave +the quality that had been desired, and the next thing was to determine +the commercial value of the process. + +“In January, 1905, a building owned by the Merrell-Soule Company at +Fayetteville, N. Y., was equipped, and powdered milk was produced, +in a small way, by this spray process. Enough was marketed, and with +sufficiently gratifying results, to warrant the company in going ahead +with the enterprise. + +“Meantime, patents had been applied for, and the patent office had +referred the Merrell-Soule Company to a United States patent granted +in 1901 to Robert Stauf, of Posen, Germany, which seemed to cover the +process. F. C. Soule, president of the Merrell-Soule Company, thereupon +went to Germany and bought not only the United States patent held +by Stauf, but also thirteen foreign patents owned by Stauf and his +associates. + +“The wisdom of the purchase of all the patents held by the Stauf +interests has since been amply demonstrated. In 1915, patent litigation +which had been in the courts for three years was decided by the Court +of Appeals in favor of the Merrell-Soule Company, the decision being +based on this company’s possession not only of its own patents, but +also of the basic patents governing the spray process of powdered milk +manufacture. + +“Following the success of the experiment at Fayetteville, the +construction of the first Merrell-Soule Powdered Milk factory, at +Arcade, N. Y., was begun in 1906. Before this factory was completed, +it had been discovered that a better product could be obtained by +condensing the milk in a vacuum pan before spraying. This resulted +in new patents covering what was known as the Merrell-Gere process, +embodying the original Stauf method and the improvement mentioned. + +“Since then many other improvements have been made at the Merrell-Soule +plants, many other patents taken out. The first powdered milk factory, +at Arcade, was followed by a second, at Little Valley, N. Y., in 1909. +Since then factories have been established at Frewsburg, N. Y., Union +City, Pa., Waterford, Pa., Farmersville Station, N. Y., Warsaw, N. Y., +Gainesville, N. Y., Attica, N. Y., and Omaha, Neb. + +“Consumption of milk has increased from 18,000 quarts per day, in 1906, +at Arcade, to 300,000 quarts per day, at the present time, in the ten +factories. The output of powdered milk has grown from 2,500 pounds per +day, twelve years ago, to a present capacity of 50,000 pounds per day. + +“These products include Powdered Skimmed Milk, Butterfat Powders, of +varying butterfat content, ‘Cream Powders,’ which contain up to 72 per +cent. butterfat, and Powdered Buttermilk.” + + +=25. Uses of Merrell-Soule powder in ice-cream.=--“The ice-cream +manufacturer demands a milk or cream product which is clean, which +will not sour quickly, which is not a breeder of bacteria, and which +gives him the largest percentage of milk solids in proportion both to +its bulk and its cost. All these essentials he finds in Merrell-Soule +powdered milk. Its powdered form insures the greatest possible purity +and cleanness, as is attested by many authorities. There need be no +loss through souring, no sticky, half-empty cans standing around, +gathering flies and breeding bacteria, when Merrell-Soule powdered milk +is used. The ice-cream man makes up just what he needs for the day’s +business. He can make up a big supply of cream, for a sweltering day’s +run, or a small amount for a cool day. A sudden drop in temperature +will not leave him with a lot of cream on hand that must either be used +or spoiled. It has been proved that Merrell-Soule powdered milk shows a +far smaller bacteria count than any other form of milk, and it offers +no breeding place for microbes. + +“Merrell-Soule powdered milk can be put to many uses in the ice-cream +factory:-- + +“1. In the production of milk or cream from powdered skimmed milk, +butter and water. + +“2. The production of skimmed milk from powder and water. + +“3. The standardization of the milk solids in the ice-cream batch. + +“4. Furnishing the necessary skimmed milk solids. + +“5. Blending butter and the powdered skimmed milk with liquid whole +milk of any fat content, for the complete total milk solids of the +batch. + +“Other uses could be mentioned, but these will give the ice-cream maker +an idea of the importance of Merrell-Soule powdered skimmed milk in his +business. + +“Many of the large ice-cream makers are beginning to realize the losses +which they incur every year through using condensed milk to raise the +per cent of milk solids in their ice-cream. + +“By the use of powdered skimmed milk they have an easy and accurate +means of holding the solids to any desired percentage. + +“Merrell-Soule powdered skimmed milk does not take the place of +gelatines, ice-cream powders and the like, which prevent the ice +crystals in ice-cream, but it does provide the solids, not fats, which +give ‘body and texture’ to the ice-cream and makes it smooth, velvety +and palatable. + +“Almost every ice-cream maker has his own formula for his mix, which +gives the best satisfaction to the trade he serves, and for this reason +we will not print any ice-cream formulas. We will be glad, however, to +furnish formulas which have given good results, to any ice-cream maker +who applies to us. + +“In our own experimenting, and in practical work in some of the large +ice-cream factories, we have found the powdered skimmed milk to be a +wonderful help to ice-cream makers in a great many ways.” + + +=26. Ekenberg powdered milk.=[13]--“The Ekenberg process was invented +by Dr. Martin Ekenberg of Stockholm, Sweden. Dr. Ekenberg had +experimented with milk drying for some years, and his father, who was +an eminent chemist, also, had devoted considerable time to this problem. + +[13] This description was given by L. P. Bennett, president of the +Ekenberg Co., Cortland, N. Y. + +“The Ekenberg process is the result of these investigations, and the +machine which Dr. Ekenberg invented, he called the Ekenberg Exsiccator. +This consists of a single drum with conical shaped ends, revolving in a +vacuum chamber. The milk is introduced into the chamber through various +pipes and is sprayed into the conical or bowl shaped ends of the +revolving drum,--the drum being heated by steam at a low temperature. +The vacuum maintained in the chamber, is from 25 to 27 inches, and as a +result, the temperature in the chamber is low, not exceeding 100° F. + +“The milk upon being introduced into the bowl shaped ends is evaporated +to a considerable degree and then passes off into the suction pipe +of a pump, from which the milk is again introduced into the vacuum +chamber, this time upon the periphery of the drum, to which it adheres, +and is then removed by a series of scrapers or knives. It will be +seen that the milk is only upon the drum during about two-thirds of +one revolution. The dried product falls into another chamber which is +separated from the main vacuum chamber by a series of air locks, so +that it may be removed at will from the exsiccator, without stopping +the continuous working of the machine. + +“When the dried product is removed, its condition is that of light +fluffy flakes. It is then allowed to stand in a chamber heated to about +90° F. for about one hour, during which time, the lactose crystallizes. +From this chamber it is removed, and then milled in the same manner as +wheat is milled in the manufacture of wheat flour.” + + +=27. Uses of Ekenberg powder in ice-cream.=--“Ekenflor is the trade +name given to the many grades of powdered milk made from skimmed milk, +partly skimmed milk, or whole milk. In using Ekenberg Powdered Milk for +ice-cream it is not necessary to change the present formulas, but only +to adapt then to the use of milk in dry form. + +“The raw milk from which Ekenflor is made is drawn from inspected +dairies and is manufactured in clean sanitary factories and is +therefore of the finest quality. + +“Ekenflor does not sour or draw flies, and its use by the ice-cream +maker can not fail to reduce the chance of unsanitary conditions in +his factory and his losses from spoiled milk. + +“There is always ‘a feast or a famine’ in the raw-milk market, and +as our powdered skimmed milk keeps almost indefinitely without cold +storage, it is always ready for immediate use, no matter how sudden +or great the demand may be. Its use makes the ice-cream manufacturer +independent of his local supply of milk or cream or condensed milk and +of the local prices.” + + +=28. Butter.=--For the making of emulsified or homogenized cream, +butter is ordinarily employed to supply the milk-fat. Unsalted butter +that is clean flavored and made from clean cream is to be desired. +If the butter is produced from inferior cream or has any undesirable +flavor, the cream made from it will have the same undesirable flavor. + +It is the usual practice to store the butter during the period of low +prices, which is commonly the summer, and then to use it when prices +are high, usually the winter. The question of the kind of butter and +method of storage is a very vital one. It is generally considered that +sweet cream butter holds better in storage. The temperature of storage +should be as near 0° F. as possible. + +The successful storing of butter, requires an intimate knowledge both +of market conditions and the desired quality of butter for storage. +The daily prices and movements of butter, in and out of storage, +and the daily receipts in the different markets and the sales, may +be obtained from the daily and weekly reports made by the Bureau of +Markets, United States Department of Agriculture. In New York City, the +market reports are also made in the “Price Current,” published by the +Urner Barry Company. Before storing butter, these reports should be +studied carefully, to make sure that the market conditions will warrant +storage. The quality of the butter can be determined by the market +grades or by the actual examining by an expert butter judge. Usually +when the ice-cream manufacturer purchases butter for storage, the +quality will be determined by the market grade, as personal examination +is seldom possible. + + + + +CHAPTER IV + +_SUGAR, CHOCOLATE PRODUCTS, FRUITS, STABILIZERS AND FILLERS_ + + +Besides the milk products, a number of other materials are used in +ice-cream. These are embodied in small amounts but their quality is of +vital importance. For this reason they are briefly discussed. + + +=29. Sugar.=--For sweetening the ice-cream, granulated sugar is usually +employed. This may be either cane- or beet-sugar, and should be free +from all visible dirt. Sugar seems to contain many mold spores and +so should be examined to determine the presence of mold or bacteria. +However, during the war, in order to conserve the supply of granulated +sugar, various substitutes were used, such as corn sirup, invert sugar, +honey and maple sirup. + + +=30. Invert sugar.=--Ruehe[14] gives the following directions for +making invert sugar: + +[14] Ruehe, H. A., “Conserving sugar in ice cream manufacture,” Ill. +Exp. Sta. Circ. 219, 1918. + +“Cane sugar (or beet sugar) can be inverted by the simple process of +heating in the presence of an acid. The chemical reaction that takes +place results in the same products being formed as are formed when the +sugar (sucrose) is taken into the human body, the sugar forming equal +parts of dextrose and levulose. The following formula may be used in +making invert sugar syrup of such sweetness that a pound of the syrup +will replace a pound of sugar: + + 100 pounds of sugar + 44 pounds of water + 50 grams of powdered tartaric acid + +These ingredients are mixed together and boiled for 30 to 35 minutes. +If boiled longer than 35 minutes, the syrup darkens in color and a +flavor develops which tends to make the syrup resemble glucose syrup, +and this is somewhat undesirable. This solution boils at a temperature +of about 221 degrees Fahrenheit. A steam pressure kettle can be used +very satisfactorily or an open candy kettle over a steady fire may be +used. If the solution is boiled too vigorously, there will be too large +a loss by evaporation. Ordinarily the loss will be from 3 to 5 per cent. + +“The above formula should make 140 pounds of syrup, and if there is +considerable loss due to evaporation, the syrup can be brought up to +this weight by the addition of water. The resultant invert sugar syrup +is not unlike strained honey in appearance and taste. It contains +about 71.4 per cent of sugar and it tastes considerably sweeter than +a sugar syrup of the same strength. It does not crystallize, and it +mixes readily with the ingredients of the ice cream. It can be used in +the same proportions as sugar, the amount necessary for ten gallons of +ice cream being 6.5 to 7 pounds. It gives very satisfactory results in +freezing and a pleasant flavor in the finished product. + +“It can be readily seen that by using the above method the sugar supply +can literally be stretched, for with only 71.4 per cent as much sugar +as is now being used in ice cream, the same degree of sweetness can be +obtained.” + + +=31. Sugar-saving substitutes.=--Frandsen,[15] while working on +sugar-saving substitutes, reached the following conclusions: + +[15] Frandsen, J. H., Rovner, J. W., and Luithly, John, “Sugar-saving +substitutes in ice cream,” Neb. Exp. Sta., Bul. 168, 1918. + +“1. Four formulas have been worked out which save from 30 per cent to +50 per cent of cane sugar in the mix: + + I. 44 lbs. 17 per cent cream + 4 lbs. cane sugar + 1³⁄₄ lbs. corn syrup (glucose) + 4 oz. vanilla + 4 oz. gelatine + + II. 44 lbs. 17 per cent cream + 2.9 lbs. cane sugar + 2.9 lbs. corn syrup + 4 oz. vanilla + 4 oz. gelatine + + III. 44 lbs. 17 per cent cream + 1¹⁄₄ lbs. cane sugar + 4¹⁄₂ lbs. invert sugar + 4 oz. vanilla + 4 oz. gelatine + + IV. 44 lbs. 17 per cent cream + 1¹⁄₄ lbs. corn syrup + 1¹⁄₄ lbs. invert sugar + 2¹⁄₄ lbs. cane sugar + 4 oz. gelatine + 4 oz. vanilla + +“2. The ice cream prepared according to these four formulas meets the +requirements of good ice cream. + +“3. Corn syrup dissolves with difficulty in cold cream. When added to +cream before pasteurizing, it dissolves readily. + +“4. In hydrolyzing the syrups, excessive heating should be avoided. + +“5. When invert sugar and corn syrup are used as the only source of +sweetening, a rather noticeable syrupy flavor is imparted to the ice +cream. + +“6. When invert sugar, cane sugar and corn syrup are used in the +proportions indicated in Formula No. 4, no objectionable flavor is +noticeable. + +“7. It is thought that hydrolyzing corn syrup in the presence of an +acid will enhance its sweetening properties. + +“8. In addition to saving cane sugar, all four formulas lower the cost +of sweetening per gallon of ice cream. + +“9. Corn sugar can replace 50 per cent of cane sugar in the mix. + +“10. None of the substitutes so far tried will satisfactorily replace +all the cane sugar in the ice cream mix.” + + +=32. Cocoa and cocoa products.=--The various chocolate and cocoa +preparations are manufactured from the bean of the tree _Theobroma +Cacao_, of the family of Sterculiaceæ. This tree averages 13 feet in +height, and its main trunk is from 5 to 8 inches in diameter. It is a +native of the American tropics, being especially abundant and growing +under best conditions in Mexico, Central America, Brazil and the West +Indies. + +The cocoa beans of commerce are derived chiefly from Ariba, Bahia, +Caracas, Cayenne, Ceylon, Guatemala, Haiti, Java, Machala, Maracaibo, +St. Domingo, Surinam and Trinidad. Besides these, the Seychelles and +Martinique furnish a small amount. + +The plant seeds, or beans, grow in pods, varying in length from 23 to +30 centimeters, and are from 10 to 15 centimeters in diameter. The +beans, which are about the size of almonds, are closely packed together +in the pod. Their color when fresh is white, but they turn brown on +drying. + +The gathered pods are first cut open, and the seeds removed to undergo +the process of “sweating” or fermenting, which is conducted either in +boxes or in holes made in the ground. This process requires great care +and attention, as on it depends largely the flavor of the seed. The +sweating operation usually takes two days, after which the seeds are +dried in the sun until they assume their characteristic warm red color, +and in this form are shipped into our markets. + + +=33. Manufacture of chocolate and cocoa.=--For the production of +chocolate and cocoa, the beans are cleaned and carefully roasted, +during which process the flavor is more carefully developed, and the +thin, paper-like shell which surrounds the seed is loosened and is +very readily removed. The roasted seeds are crushed, and the shells, +which are separated by winnowing, form a low-priced product, from which +an infusion may be made having a taste and flavor much resembling +chocolate. + +The crushed fragments of the kernel or seed proper are called cocoa +nibs, and for the preparation of chocolate they are finely ground into +a paste and run into molds, either directly or after being mixed with +sugar and vanilla extract or spices, according to whether plain or +sweet chocolate is the end product. + +For making cocoa, however, a portion of the oil or fat known as the +cocoa butter is first removed, by subjecting the ground seed fragments +to hydraulic pressure, usually between heated plates, after which the +pressed mass is reduced to a very fine powder, either directly or by +treatment with ammonia or alkalies, to render the product more soluble. +It is held that the large amount of fat contained in the cocoa seeds +(varying from 40 to 54 per cent) is difficult of digestion to many, +such as invalids and children, and hence the desirability of removing +part of the fat. + + +=34. Composition of cocoa products.=--The chief constituents of the +raw cocoa bean, named in the order of their relative amount, are fat, +protein, starch, water, crude fiber, ash, theobromine, gum and tannin. +In the roasting there is reason to believe a volatile substance is +developed much in the nature of an essential oil, which gives to the +product its peculiar flavor, and is somewhat analogous to the caffeol +of coffee. + +Tannin, the astringent principle of cocoa, exists as such in the raw +bean, but rapidly becomes oxidized to form cocoa red, to which the +color of cocoa is due. + + +=35. Adulteration of cocoa products and standards of purity.=--The +following are the United States standards: “Standard chocolate should +contain not more than 3 per cent of ash insoluble in water, 3.5 per +cent of crude fiber, and 9 per cent of starch, nor less than 45 per +cent of cocoa fat. + +“Standard sweet chocolate and standard chocolate coating are plain +chocolate mixed with sugar (sucrose), with or without the addition of +cocoa butter, spices, or other flavoring material, containing in the +sugar and fat-free residue no higher percentage of either ash, fiber +or starch than is found in the sugar and fat-free residue of plain +chocolate. + +“Standard cocoa should contain percentages of ash, crude fiber, and +starch corresponding to those of plain chocolate, after correcting for +fat removed. + +“Standard sweet cocoa is cocoa mixed with sugar (sucrose) containing +not more than 60 per cent of sugar, and in the sugar and fat-free +residue no higher percentage of either ash, crude fiber, or starch than +is found in the sugar and fat-free residue of plain chocolate. + +“The removal of fat, or the addition of sugar beyond the above +prescribed limits, or the addition of foreign fats, foreign starches, +or other foreign substances, constitutes adulteration, unless plainly +stated on the label. + +“The most common adulterants of cocoa are sugar and various starches, +especially those of wheat, corn and arrowroot. Starch is sometimes +added for the alleged purpose of diluting the cocoa fat, instead of +removing the latter by pressure, thus, it is claimed, rendering the +cocoa more digestible and more nutritious. Unless its presence is +announced on the label of the package, starch should be considered as +an adulterant. Cocoa shells are also commonly employed as a substitute +for, or an adulterant of, cocoa. Other foreign substances found in +cocoa are sand and ground wood fibre of various kinds. Iron oxide is +occasionally used as a coloring matter, especially in cheap varieties. + +“Such adulterants as the starches and cocoa shells are best detected by +the microscope. The presence of any considerable admixture of sugar is +made apparent by the taste. Mineral adulterants are sought for in the +ash.” + + +=36. Chocolate sirup.=--Ice-cream may be flavored by pouring a +chocolate sirup over it. The following materials are used in making the +sirup: + + Powdered cocoa, 1 pound + Sodium chloride, 6¹⁄₂ drams + Granulated sugar, 16 pounds + Shredded gelatine, 2¹⁄₂ ounces + Vanilla extract, 2¹⁄₂ ounces + +Dissolve the gelatine in 10 pints of cold water, heat to the boiling +point, then add 15 pounds granulated sugar, stirring occasionally +until dissolved. Triturate 1 pound granulated sugar with the powdered +cocoa and sodium chloride until thoroughly mixed, then add to the hot +solution; boil for ten minutes, stirring constantly; strain while hot +and when cool, add the vanilla. + + +=37. Fruits.=--Many different fruits may be used to flavor ice-cream. +The principal ones are pineapple, cherry, strawberry, raspberry, +lemon, orange, peaches, and the like. In their season, the fresh +ripe fruit is used as a flavoring. For the period when the fresh +fruit cannot be obtained, the fruit may be canned, preserved without +chemicals, preserved with chemicals, or dried. Only fresh ripe fruits +should be employed, whether used fresh or held in some manner; since +for ice-cream-making the fruit must be broken into small pieces, it +is often cheaper to obtain from canneries small fruits or broken or +crushed pieces. + +In some of the large ice-cream plants the fruits are preserved in large +jars (Fig. 6) by the addition of sugar and kept cold but not frozen. +Fruits preserved in this way give the product a flavor similar to fresh +fruits. Fruit extracts may be derived from the fruit, by fractional +distillation in dilute alcohol. These extracts should not be confused +with artificial or imitation flavors. The latter are often coal tar +ethers or esters. In order to obtain the desired flavor, it is usually +necessary to combine fruit extracts with the canned and preserved +fruits. + + +=38. Nuts.=--Only sound non-rancid nuts should be employed to flavor +ice-cream. For flavoring, the nut meats should be blanched by soaking +in hot water, and then removing the outer coating or covering; +these blanched nuts should then be ground. Often broken nuts can be +secured cheaply. A flavoring extract may be made from the nuts. In +many respects this is desirable because a more pronounced flavor is +obtained. For example, pistachio nuts give a very weak extract. It is +the custom to use pistachio flavoring and color the ice-cream green. + +[Illustration: FIG. 6.--Fruit storage in large ice-cream plant.] + + +=39. Stabilizers and fillers.=--If ice-cream is not consumed as soon as +made, ice crystals will begin to form unless some stabilizer is used. +This is a substance added to ice-cream to prevent the formation of ice +crystals which cause a grainy bodied product. Stabilizers are sometimes +known as “holders” or “colloids” and commonly as “binders.” A “filler” +is some substance added to the ice-cream to cheapen it, usually to +replace the milk-fat and milk solids not fat. A “filler” may serve +the purpose of a “binder” or a “stabilizer,” but a stabilizer cannot +take the place of a “filler.” The common stabilizers are gelatine and +gum tragacanth. The common fillers are the various starches, such as +cornstarch, rice flour, arrowroot, wheat flour, eggs, an excess of +gelatine and the like. + + +=40. Gelatine.=--Commercial gelatine is an animal product made from +bones, hides, skins, tendons, horn piths, tannery trimmings and any +kind of connective tissue from the animal’s body. Pure gelatine is an +amorphous, more or less transparent substance of vitreous appearance. +It is brittle when dry, free from color, taste and smell. Gelatine and +glue are manufactured from the same materials, more care being used in +making gelatine. + +The detail process of making gelatine varies in the different +factories, but the general steps are as follows: Treating and cleaning +the raw material; dissolving gelatine; concentrating; chilling and +spreading; drying; finishing; including grinding and packing. Gelatine +is put on the market in sheet, flake, shredded and powdered form. If +made from clean materials, no objection can be raised against its use +as a food. Gelatine swells in cold water, absorbing five to ten times +its weight of water. This is sufficient water to dissolve it at a +temperature of 85° F. to 90° F. The strength or gelatinizing power of +different samples of gelatine varies within wide limits. The following +is a simple method to compare different gelatines: Take ten grams of +the sample and soak over night in 100 cubic centimeters of cold water. +The next morning dissolve the gelatine at a temperature of 80° C. First +note the odor. It should not be pronounced or disagreeable. Determine +length of time it takes for a 50 cubic centimeter pipette full to run +out. Note the time it takes to gelatinize. Test the strength with a +jelly tester which is a simple arrangement to determine the weight +necessary to force a plunger into the gelatine. + +[Illustration: FIG. 7.--Steam-jacketed kettle for heating gelatine.] + + +=41. Preparing gelatine for use in the ice-cream.=--In order to +utilize gelatine in ice-cream, it must be brought into solution. A +steam-jacketed copper kettle is usually employed for heating the +gelatine (Fig. 7). If a smaller quantity is taken or a special gelatine +cooker is not available, a double boiler or a can set in water can be +used. Whatever utensil is selected to cook the gelatine, it should be +kept clean. In many ice-cream factories, the gelatine cooker is badly +neglected. Before the gelatine is heated, it should be soaked in cold +water. One pound of gelatine should be put into about eight quarts of +water. Some prefer to use milk instead of water. The gelatine should be +stirred into the water rather than the water poured on to the gelatine. +This will to a large extent eliminate the formation of lumps which +would require excessive heating to break them down. The gelatine should +be soaked from twenty to thirty minutes in cold water before the heat +is applied. This soaked or soft gelatine should then be placed in a +water-jacketed heater and heated to a temperature of 165° F. to 170° +F. In case the gelatine is soaked in milk, it should not be heated +above 145° F. A higher temperature is very liable to give it a cooked +or scorched flavor. At this lower temperature, it is advisable to +hold it ten or fifteen minutes to make sure that the gelatine is all +broken down. It is necessary to heat the gelatine to the temperature +mentioned above to secure the best results. The eye cannot determine +when the gelatine is all broken down. There is danger of over-heating; +it should not be held at high temperature for long periods of time nor +allowed to boil. In putting the gelatine into the mix, it should be +done at the above mentioned temperatures for dissolving; not all at one +time, but poured in slowly and with as rapid agitation of the mix as +possible, and it will distribute itself more evenly before it has time +to congeal. A good gelatine will jelly at a temperature of 85° to 90°, +according to the proportions used; so that when pouring gelatine into +a mix with a temperature probably of 45° or 50°, it is very liable to +harden and make the ice-cream lumpy. + + +=42. Gum tragacanth.=--This is a compound gum obtained from a shrub, a +species of Astragalus. In July or August the leaves are stripped from +the shrub and a hole made in the bark. The shape of the hole regulates +the form of the gum, a longitudinal cut making the leaf or flake form, +a puncture the thread form, and an irregular hole a knob-like mass. The +gum is gathered by the natives. Dry weather gives a whitish colored gum +which is best; wet and dusty weather give an inferior yellowish gum. + +Gum tragacanth will absorb fifty times its weight of water. For use in +ice-cream, the gum is soaked in water, one ounce of gum absorbing two +quarts of water. At least twenty-four hours should be allowed for this +absorption. Before being put in the ice-cream, the mixture should be +strained to remove any lumps. If it is not all to be used as soon as +soaked, a gum stock may be prepared by adding sugar at the rate of two +pounds for each quart of water. This will act as a preservative. Gum +tragacanth is odorless and tasteless. Just how it acts as a binder is +not known. + + +=43. Other substances used as binders.=--Two plants, Irish and Iceland +moss, are sometimes used as binders. The former is a sort of algæ and +the latter a lichen. They are both very low in food value. + + +=44. Eggs.=--In some kinds of ice-cream, eggs are necessary to give +the characteristic body and texture. When eggs are employed, it is +usually as a filler, since it is possible to reduce the percentage of +either the milk-fat or milk solids not fat or both. The usual practice +is to separate the yolks and whites of the eggs. The yolks are cooked +with the cream if used and the whites beaten and added just before the +ice-cream is frozen. Eggs usually give ice-cream a smooth texture and a +firm body. They also impart a characteristic flavor. + + +=45. Starchy fillers.=--Several starchy substances, such as cornstarch, +rice flour, arrowroot and wheat flour, are sometimes used in large +quantities and so become fillers. They give a characteristic starchy +flavor to the ice-cream. They are often employed to cheapen the +product. The starches are ordinarily cooked before using but sometimes +are mixed with the sugar and used without cooking. + + +=46. Prepared ice-cream powders.=--A large number of prepared +substances, both powders and liquids, is on the market. These are often +used in the place of some other binder. They may contain any or all of +the materials previously mentioned, and in addition they often contain +sugar to give both bulk and weight. These powders are usually added to +the ice-cream by mixing with the sugar. Many times, in proportion to +the results obtained, they are found to be expensive. + + +=47. Rennet.=--Another binder is some form of rennet. Its use is not +common and is ordinarily in combination with other materials. + + + + +CHAPTER V + +_FLAVORING EXTRACTS_[16] + + +[16] This article on flavoring extracts is furnished by the Joseph +Burnett Extract Co., Boston, Mass. + +Because of the distinct taste which the flavoring extract imparts to +the ice-cream, it is important that it be of good quality. The vanilla +extract is most common, but lemon, orange, pistachio, almond, various +fruit, and others are used to some extent. + +Flavoring extracts are prepared commonly by grinding or chopping the +sources of their various flavors and steeping or dissolving them in +alcohol; or by distilling them, wholly or fractionally; or, when +necessary for any reason, simulating them by chemistry, or by the use +of a flavor source to all intents the same as the original. + + +VANILLA EXTRACT + +Extract of vanilla, properly made, is the pure essence of the vanilla +bean, dissolved in alcohol. + +Although there are fifty or more kinds of vanilla plant, the only +one with a fruit suitable for use in flavoring extract is _Vanilla +planifolia_, so called by botanists for its flat leaves. It is a native +of the valley of Mazantla, in Vera Cruz, Mexico, seemingly the only +place where conditions of soil and climate suffice to bring it to its +highest point of cultivation. The other vanillas, native to various +parts of Spanish America, are fit only for use in perfumery and soap, +because, though aromatic, they are rank in taste. + + +=48. Nature of vanilla plant.=--The plant of vanilla is an orchid, +having roots in the air as well as in the ground. It clings to trees +or frames, twining around them as it grows, and favors most a light, +loose soil, well drained, with “quilted sunshine and leaf-shade,” a +condition naturally brought about by the foliage of the protecting +trees. In Mexico it is grown from cuttings set out in the forest, one +to a tree; this support, together with 70 to 90 degrees of continued +heat, frequent rains, and a final dry season being needful to its best +growth. Frost is deadly, and in too close planting disease is likely to +ravage the crop. + +After eighteen months, the vine is clipped to check its growing until +it bursts into flower, which occurs in September. The stem of the +vanilla is thick and round, the leaves large, smooth and pointed, +the flower beautiful, much resembling the tuberose, and delightfully +fragrant. + +Formerly the blossoms were fertilized by a small bee, which carried +the pollen from one to another, for the plant is of two sexes. At +present this is done by hand--a better way, inasmuch as only the best +flowers need be fertilized, the plant thereby keeping vigorous and +healthy. Artificial pollenizing developed from transplanting vanilla in +the island of Reunion, where the crops originally failed for lack of +insects to carry the pollen. + +Following each blossom comes a small pod, but most of these pods fall +off. The remaining ones mature in about six weeks, growing in bunches +of six to ten, and resembling bananas, being five to ten inches long, +yellow green, and banana-like in shape. They are watery and tasteless, +without the pleasant aroma of vanilla, the well-known taste and smell +of which must be brought out by curing. If left on the vine, they ripen +slowly, but usually they are picked before they ripen, as otherwise +they split in curing. When this happens they are known to the trade as +“splits,” and are considered undesirable on account of their full and +heavy flavor. + + +=49. Curing vanilla beans.=--After picking, the Mazantla beans are +transported to Papantla, the largest town in the valley, to be cured. +The process is laborious, and although somewhat primitive, very simple. + +The beans are exposed on frames to the sun by day and by night are +wrapped in blankets under cover. This continues, in fair weather, for +about a month; then the beans are dried indoors for forty days more, +until they turn a deep rich brown in color, and become delightful to +the smell. If the weather is wet, they are moistened, blanketed, and +heated in ovens, the heat being moderate and varied with the size of +the beans; after which they are by turns exposed to the air and heat +until cured. The sun drying is preferred, as it gives the beans better +keeping qualities. Such is the process in effect, but in fact each bean +is treated separately; for proper curing, to bring out the desired fine +qualities of taste and smell, is of the utmost moment; and only native +judgment, or the skill born of long handling, ever gives the real +adroitness. Badly cured beans lack any stable taste or smell, and are +likely to become moldy. Their use in trade is made possible, in this +case, by scraping and chopping them up with poor and broken beans and +those that fell early from the vines; then they are sold under the name +of “Mexican cuts,” chiefly to manufacturers of cheap extracts. + + +=50. Marketing vanilla beans.=--The long fine beans, resembling thin +cigars, are molded, pulled, and tied in bundles of 100 to 150, varying +in length from six to eleven inches, and in weight from twelve to +twenty-four ounces. The bundles are packed forty to a tin, and shipped +four tins to a case in sweet-smelling cedar boxes. The entire Mexican +output is consigned to the United States, where it brings from seven to +ten dollars a pound. + +The Aztecs knew the properties of vanilla, and are said to have +called the plant thilxochitl. They used the bean in making chocolate, +through which it became familiar to their Spanish conquerors, and thus +to Europe. The name vanilla is derived from the Spanish word vaina, +meaning sheath or pod, and the suffix -illa, little. The use of vanilla +in chocolate was its only notable one for many years, although during +that time great medical properties were claimed for it. It was not +until the eighteenth century that some person now unknown discovered +its general utility for flavoring. + + +=51. Production of vanilla beans.=--Vanilla cultivation in Mexico was +in the hands of the Indians for centuries, but in 1896 the government, +claiming they had no title, drove them off and sold the land to Greeks, +who now control the industry there. + +Almost every European power has tried to grow vanilla in the tropics, +outside of Mexico. Many of the early trials were failures; none has +been a complete success, at least in so far as rivaling the fine +quality of the Mexican product is concerned. Cuttings were transplanted +in the island of Reunion and grown by artificial pollenizing, as has +been said, but the resulting beans were not as good as the parent +beans of Mexico. Reunion was formerly known as Bourbon Monarchy, but +the French, who had every reason to hate the name, rechristened the +island; the beans, notwithstanding, are still called Bourbon beans. + +Vanilla grows in Reunion much as it does in Mexico, except that it +takes longer to develop. The great difference is in the curing, for +there, owing to the climate, the sun treatment is inexpedient. The +beans, placed in baskets, are plunged into hot water for about twenty +seconds, drawn out to drain for as many minutes, and then wrapped in +blankets to be sunned during the warm hours for five to eight days. +They are housed at night as in Mexico, but drying is also hastened +chemically with chloride of calcium (the basis of lime). After curing, +the beans are straightened, graded by size, smell, and soundness, +bundled and packed in tins which weigh, when ready for export, from ten +to twenty pounds each. + +Tahiti exports a particularly inferior quality of beans. They are +grown from Mexican or Bourbon slips, but the change of soil and +climate imbues them with an unmistakable rankness, to which, up to +within a few years, were added careless growing and packing, in nowise +improving them. Although inspection by the French colonial government +has somewhat bettered the care of these beans, their flavor is probably +unchangeable. Tahiti beans are all shipped to the United States, whence +those not used are reshipped to Europe. They are sorted here into three +grades: pink label, best; white, fair; green, poor; but the only real +difference is their length and appearance. + +A small crop of beans grown from Mexican slips is raised in the island +of Guadeloupe; they are known to the trade as “South Americans,” and +are of low quality, without the finer characteristics of good vanilla. + +The average world’s production of vanilla is as follows: + + Mexican: + Whole beans 240,000 pounds + Cuts 80,000 „ + Bourbon: + (From all sources) 700,000 „ + Tahiti 450,000 „ + South American 25,000 „ + Total 1,495,000 „ + + +=52. The ingredients of vanilla extract.=--Vanilla beans, glycerine, +sugar and alcohol are the only ingredients requisite or advisable in a +vanilla extract; consequently the excellence of such an extract rests +in the quality of the beans and of the alcohol employed, and in the +means and skill devoted to employing them. + +The process at its best is chopping or grinding the beans and treating +them with dilute alcohol of 20 to 70 per cent strength, in the +proportion of one part of the bean to ten parts of the liquid, the +alcohol acting as a solvent. The old-fashioned and as yet unequaled +way is to treat the beans by steeping and dissolve out the soluble +matter. The chopped beans are placed in a cask and the dilute alcohol +poured over them; they are then left to soak for one to twelve weeks, +when the extract is drawn off and the sugar added to it, and it is +either bottled immediately or aged. Aging greatly improves it, but few +manufacturers care to assume the added cost. + +Another method of obtaining the extract is by distillation; that is, +by evaporating and condensing the liquid in which the beans have been +steeped. There is also a machine which effects the result more rapidly +by pumping the liquid steadily through the chopped beans, at an even +temperature. Many other means are also employed. They are all cheaper +than the old-fashioned way, but have nothing to recommend them from the +consumer’s point of view. Distillation, for example, might ruin the +delicate flavor of choice Mexican beans; while no process would ever +impart one to Bourbons or Tahitis. + + +=53. The chemistry of vanilla.=--Given the highest grade of Mexican +beans and pure cologne spirit--the trade name for doubly distilled +alcohol--with the old-fashioned method of compounding them, and +there remains to vanilla extract-making only the knowledge and skill +available in the process. These, however, are far from comprising the +whole secret of success. Although seemingly a matter of chemistry, +extract-making has always been a stumbling-block to the chemist. +Chemically, there is no difference between the richest Mexican beans +and the wretchedest Tahitis, but to even a normal nose the difference +is striking and immediate. + +There is still much to be learned about the chemistry of vanilla. Its +flavor is known to be due to natural vanillin, the chief flavoring +principle of the plant, and to certain gums and resins, but of these +last next to nothing is known. Yet if aptitude and experience still +play the leading part in well-made extracts, chemistry without question +takes the center of the stage in the adulterated ones. + +Under the present law (1913), an extract may be sold as “extract of +pure vanilla” if it is made of genuine vanilla beans; consequently +“Mexican cuts,” “splits,” and rank Tahitis can be and are sold under +this label; whereas some extracts, though strictly speaking not +adulterated, are really worse than some adulterated ones. These “cheap +vanillas” are made possible by the difference in cost between fine +Mexican beans and poor defective ones, or beans of other growth; a +matter, as a rule, of four or five dollars a pound; and are readily +exposed by a comparative test in cookery or on the tongue. + + +=54. Adulteration of vanilla extract.=--A common adulterant of +cheap vanillas is artificial coumarin. Real coumarin is an aromatic +crystalline substance found in the Tonka bean or cumaru. Tonka beans +were formerly rampant in imitation vanillas, but their present high +price, due to their use in cheap tobacco, has practically curtailed +this activity. The Tonka, with its real coumarin, was bad enough--the +theory has even advanced that hay fever is due to the presence in the +air of coumarin from plants--but artificial coumarin, as flavoring, is +worse. It is a powerful drug; a coal tar product, heart depressant and +active poison. + +Artificial vanillin produced by chemistry also is employed plentifully, +not only in substitution but also for strengthening weak pure extracts. +The real vanillin is one of the odorous principles of the vanilla bean, +taking the form of tiny crystalline needles of hot bitter taste. It +is imitated chemically by combining oxygen and eugenol, a colorless +compound from oil of cloves, of bay, of cinnamon leaves, or of +allspice; or by coniferin, a compound ether obtained from wood. Lacking +the necessary gums and resins, it does not taste like real vanilla, and +needless to say, its composition is not such as to inspire confidence. + +Coumarin and vanillin are ordinarily used together in adulterating; the +mixture is then sweetened and artificially colored, with prune juice +added. This sometimes brings a substantial profit of 150 per cent to +its manufacturer. + +Fortunately detection of these subterfuges by simple means is not +difficult. A suspected extract can be tested by holding a tablespoon +of it over a lamp or other flame until about two-thirds of the liquid +has evaporated; then, if on adding water to the remaining third until +the spoon is full, the extract remains clear, undoubtedly it is not +vanilla but an artificial product. Taste and smell, if one is familiar +with true vanilla, are often test enough; coumarin in particular can +be recognized by its odor, which is like that of Indian grass or “wood +grass.” + +The best test for the quality of vanilla is to pour a few drops on a +lump of sugar, and then suck the extract through the lump. To determine +the relative values of two or more extracts, a separate lump should be +used for each. The distinction between good and bad will then be marked +sharply. Finally, to avoid adulterated extracts, the label should be +read carefully. + + +LEMON AND ORANGE EXTRACTS + +Owing to its refreshing aroma, convenience in use, and low cost, lemon +extract holds popular favor as second to vanilla. + +Extract of lemon is made by dissolving lemon oil, chiefly from skin +of the fruit, in alcohol. To conform to the government standard, the +compound must contain at least 5 per cent of the oil. + +The world’s yearly yield of lemon oil is about two million pounds, of +which southern Italy and Sicily produce the most, although there is +some output from France and Spain. The best is shipped from Messina. + + +=55. Preparation of lemon oil.=--Lemon trees flower in the summer, +and the fruit is picked from November to February. As the oil from +the later fruit has the richer color, many makers prefer it, but the +earlier oil has the finer flavor. + +Lemon oil is extracted most satisfactorily by washing and paring the +lemon skin so that it comes off in one piece, and then pressing it +against a clean sponge. The sponge absorbs the oil, and when full is +squeezed into a container from which the oil is filtered and packed in +sealed copper vessels, holding either ten or twenty-five pounds, for +shipment. + +In France the fruit is sometimes rolled about in vessels driven full +of spikes, the oil running into a receptacle below. Another method is +to press the whole fruit in a large vat, add water, and distill the +resulting mixture. This has been tried in California, although without +success, since the oil thus secured is very bitter, tasting strongly of +turpentine. + + +=56. The chemistry of lemon oil.=--The oil is known to contain a large +amount of terpenes or principles chemically like turpentine, which +would account for such a taste or smell in a poor or stale product. +These, with 6 to 10 per cent of citral, the chief flavor-giving +constituent of lemon oil, would seem to identify the peculiar lemon +taste; although there are certain unknown esters, or compound ethers, +corresponding to the salts in metals, which also are taken to be +factors of it. Citral is found in exactly the same form in limes, +mandarins, and oranges. + +Adulteration of lemon extract consists usually in either lowering +the required amount of oil, or using in place of it citral, oil of +lemon-grass, or some other natural oil containing citral. These +substitutes naturally fail to give the true flavor, because they are +lacking in terpenes, and presumably in the esters just mentioned. Many +makers, to weaken the extract, lessen the alcohol; this indicates that +their product cannot be made of lemon oil, because this will not +dissolve in dilute alcohol. In most cases, weakened extracts are made +of citral. + +Terpenless lemon and orange extracts are made from lemon and orange +oils from which the terpenes have been removed. They are much in favor +among makers of low-grade flavors because they are soluble in very +weak alcohol, and because considerably less oil is needed to make the +extract. On account of the removal of the terpenes, the flavor is of +course quite different from that of the true oils. + +Using stale lemon oil in extract is not against the law, but no one +is likely to buy more than once a product so compounded, for its foul +taste of turpentine will ruin any cooking in which the extract is used. + +To test lemon extract a little should be poured from the bottle, the +cork replaced, and the bottle shaken for a few seconds. If the bubbles +disappear at once, there is no water in the extract, and it is probably +pure. If they disappear slowly, there is water in it, and the extract +can contain no lemon oil. Or a teaspoonful of the extract may be added +to a glass of water; if small drops of oil come to the surface, and the +water, on standing, becomes cloudy, the extract is probably pure. But +if the extract dissolves immediately, leaving the water clear, it is +not pure, and contains no lemon oil. + +No adulterated extract of any kind is really cheap. It is an actual +fact that in a test of an adulterated lemon extract against a pure one +costing twice as much, the pure one at but double the cost was found to +be ten times as strong, in addition, of course, to its having by far +the better flavor. + + +=57. Orange extract.=--Like lemon, orange extract must contain at +least 5 per cent of the fruit oil. The only chemical difference +between orange and lemon oil is that the former has an infinitely +small proportion of flavoring esters not found in lemon. The two +fruits are grown in the same countries and in the same way, the +methods of producing the two oils are identical, and the tests for the +adulteration of the one extract hold good for the other. + + +=58. Fruit extracts.=--Raspberry, strawberry, cherry, apple, pineapple, +banana, and other familiar fruit flavors constitute a class of +flavoring extracts similar in character and similarly made. They can +be derived from their respective fruits, although previous to 1911 +this was thought impossible. Up to that time, imitation extracts had +been compounded chemically from coal tar ethers and esters, and ether +was added often to give them pungency. They all tasted alike and none +of them tasted like any fruit. One difficulty in making real fruit +extracts was the lack of the essential oils in the several fruits; +another, the change brought about in the delicate esters, the cause +of the flavor, by cooking, since great heat destroys them. Pure fruit +extracts are in every way immeasurably superior to the old unwholesome +and unhealthful ether preparations, of which purchasers should beware. +Fruit flavors labeled artificial or imitation are of the type; if not +labeled, they can be detected by the odor of ether rising when the cork +is drawn. + + + + +CHAPTER VI + +_CLASSIFICATION OF ICE-CREAMS_ + + +Because of the large variety of materials used and the different +methods of blending and preparing them, it is desirable to have +a classification of ice-creams. Several[17] classifications have +been made but the following, based on the materials used and the +method of preparing them, seems best adapted for general use. These +classifications have been based on the materials employed, the +flavoring materials used, and the form in which the ice-cream was put +up for market. + +[17] Mortensen, M., “Classification of ice cream and related frozen +products,” Ia. Exp. Sta., Bul. 123, 1911; Washburn, R. M., “Principles +and practice of ice cream making,” Vt. Exp. Sta., Bul. 155, 1910; +Frandsen, J. H., and Markham, E. A., “The manufacture of ice cream and +ices,” Orange Judd Co., 1915. + + +=59. Classification of ice-cream.=--The following is based on the +materials used; the subclasses are divided according to the flavoring +materials. + +I. Plain ice-cream, often known as Philadelphia ice-cream, is made from +cream, sugar, and flavoring, with or without condensed milk or some +stabilizer. This class may be subdivided as follows: + +(1) Plain--flavors are used such as vanilla, chocolate, caramel, +coffee, mint, maple. + +(2) Fruit--fresh or canned fruits are employed for flavors, such as +peaches, strawberries, cherries, pineapples, raspberries. + +(3) Nut--nuts such as walnuts, almonds, chestnuts, pistachio, furnish +the flavoring. + +(4) Bisque--materials are used for flavoring such as macaroons, +marshmallows, grapenuts, sponge cake. + +(5) Mousse--rich whipped cream sweetened and flavor folded in, +sometimes eggs are used. + +II. Cooked ice-cream, often known as French or Neapolitan, is made from +cream, sugar, eggs, and flavoring. As custards they sometimes contain +flour or cornstarch. This class may be subdivided as follows: + +(1) Parfaits or French--flavors such as vanilla, chocolate, and the +like are the most common but various fruits are sometimes used. + +(2) Puddings--these are highly flavored with various dried and candied +fruits, nuts, and spices and eggs. + +(3) Custards--these contain flour, cornstarch, or other similar +ingredients and are almost always flavored with vanilla. + +III. Sherbets and ices are made from water or milk, sugar, often egg +albumen and a stabilizer, and flavored with fruit juices or other +natural flavorings. + +(1) Ices--made from water, sugar, and some natural flavoring without +eggs or a stabilizer. This may include granites and frappés. Granites +are frozen with little agitation, while frappés are only semi-frozen to +a slushy consistency. + +(2) Water sherbets--made the same as ices with the addition of +egg-whites and sometimes a stabilizer. If the whole egg is used, they +are sometimes called souffles. + +(3) Punches--ices or water sherbets flavored with liquors or highly +flavored with fruit juices and spices. + +(4) Milk sherbet--made from whole or skimmed-milk, sugar, and +egg-whites, with or without a stabilizer and flavored with some natural +flavoring. + +(5) Lacto[18]--made from skimmed or whole sour milk instead of sweet +milk but in other respects resembling milk sherbets. + +[18] Mortensen, M., “Lacto, a frozen dainty product,” Ia. Exp. Sta., +Bul. 140, 1913. + + +=60. Receipts for ice-cream.=--A large number of receipts or formulas +for ice-cream might be given. Each manufacturer usually has a receipt +for his own use, which is slightly different from any other. Ordinarily +ice-cream manufacturers employ the same classes of materials but +in different amounts. The receipts given are typical of those used +and give satisfactory results. So far as possible receipts will be +given which use the various materials and at the same time vary the +composition. + + +=61. Vanilla ice-cream.=--These receipts may be used as a basis for +other ice-creams by substituting other flavors. These provide a basis +for all plain ice-creams. + +Receipt No. 1. + + 40 lbs. 20 per cent cream + 9 „ sugar + 4 oz. gelatine dissolved in 4 lbs. water + 4 „ vanilla + +Receipt No. 2. + + 32 lbs. 20 per cent cream + 8 „ whole or skimmed-milk condensed + 9 „ sugar + 4 oz. gelatine dissolved in 4 pounds of water + 4 „ vanilla + +Receipt No. 3. + + 26 lbs. 18 per cent cream + 14 „ skimmed-milk condensed + 8 „ sugar + 4 oz. gelatine dissolved in 4 pounds water + 4 „ vanilla + +Receipt No. 1 will test from 14-15 per cent of fat. Receipt No. 2 will +test 13-14 per cent fat if whole milk condensed is used and 11-12 per +cent of fat if skimmed-milk condensed. Receipt No. 3 will test 8-9 per +cent of fat. + + +=62. Chocolate ice-cream.=--Either chocolate or cocoa may be employed +to give the chocolate flavor. Some manufacturers prefer one and some +the other. A thick chocolate sirup may be purchased from some flavor +manufacturing concerns. A pound to a pound and a quarter of chocolate +or cocoa is sufficient for a ten-gallon mix. The chocolate or cocoa +may be softened in either water or milk. The cocoa forms a liquid much +easier. The best way to prepare either is to put it into a double +boiler and cook until a thick sirup is formed. About two quarts of +milk or water is sufficient for a pound or a pound and a quarter of +chocolate or cocoa. This can be used with the mixes given for vanilla +ice-cream. Some manufacturers of ice-cream prefer some vanilla with the +chocolate, believing that it imparts a better flavor. + + +=63. Caramel ice-cream.=--This may be made by substituting caramel +flavor for the vanilla in each receipt. The flavor may be obtained by +caramelizing or carefully burning sugar or by adding prepared caramel +flavor. The amount of either which should be used depends on the +strength of the flavor. + + +=64. Coffee ice-cream.=--Ice-cream may be flavored by the addition +of coffee. The amount to use will depend on its strength. The coffee +should be strained and only the liquid portion added. It may be +substituted for the vanilla in the receipts. + + +=65. Maple ice-cream.=--Maple sirups or prepared maple flavor may be +used to flavor ice-cream in place of the vanilla. The amount depends +on the strength of the materials used. + + +=66. Fruit ice-cream.=--Various flavors of fruit ice-cream may be made +by substituting the fruit for the vanilla in the receipts already +given. Either the fresh fruit or the preserved or canned ones may be +used. In many cases the fruit sirups or extracts are employed either +alone or with the fruits. It is usually customary to add a small +amount of color to mix with the fruit in order to give the product +the characteristic fruit color. This is not necessary but adds to the +appearance of the ice-cream. The amount of fruit necessary depends on +its flavor; for example, fruits with a very pronounced flavor, such as +raspberry will go further than a fruit with a very delicate flavor such +as peach. Usually two quarts of preserved fruits are enough to make ten +gallons of ice-cream. The fruit should be chopped before adding. + + +=67. Nut ice-cream.=--Various nuts may be employed to flavor ice-cream +but they are not commonly used alone. The most common is pistachio. In +this case the nut itself is not utilized ordinarily but an imitation +flavor, and the ice-cream colored green. This is a trade custom. + + +=68. Bisque ice-cream.=--Various bread products may be used to flavor +ice-cream, the result being called bisque. The common material is +macaroons, but other materials such as sponge cake, grape nuts, and +dried cakes may be added. The material should be dried and then ground +through a food chopper before it is added to the ice-cream. + + +=69. Mousse.=--This differs from the other plain ice-creams as the +cream is whipped first and the flavoring then folded inside. Various +flavors may be used, but maple is the most common. + +_Mousse foundation_ + + 4 eggs + 20 egg-yolks + 1 lb. sugar + 2 qts. whipped cream + +Cook sugar to heavy thread. Beat the eggs and yolks and pour sugar in +slowly. Beat on ice until cold. Add whipped cream, mixing thoroughly. +Fruits and nuts may be added. + + +=70. Cooked ice-cream.=--No basic receipts can be given for Class +II as for Class I, in which the various flavoring materials may be +substituted. Most of the cook-books give numerous receipts which belong +to this class. In fact there are so many receipts for cooked ice-creams +that only a few of the better ones can be given; they are usually made +in small quantities. + + +=71. Parfait.=--The use of eggs makes an ice-cream of different flavor +and body. This is the main difference between parfait and the plain +ice-creams in Class I. Usually the eggs are cooked either in all or a +part of the mix before they are added to the freezer. + +Receipt No. 1. + + 40 lbs. 20 per cent cream + 10 „ sugar + 4 oz. vanilla + 8 doz. eggs well beaten + +Beat the egg-yolks till smooth, add the sugar, and beat again till it +is dissolved. Beat the whites to a stiff froth and stir into the yolks +and sugar. Mix all with the cream and cook in a double boiler to a +temperature of 180° F. for fifteen minutes. Cool to 40° F., add vanilla +and freeze. + +Receipt No. 2. + + 40 lbs. 28 per cent cream + 10 „ sugar + 4 oz. vanilla + 8 doz. eggs well beaten + 2 qts. crushed strawberries + +Beat whole eggs together, add to the mix and freeze, or the whites +may be beaten separately if desired and added after the mix is partly +frozen. + +Receipt No. 3. + + 40 lbs. 25 per cent cream + 12 „ sugar + 4 oz. vanilla + 4 lbs. chopped walnut meats + yolks of 8 dozen eggs + +Beat the egg-yolks till smooth, add the sugar and beat again. Then +add to the cream and cook in a double boiler to 180° F. for fifteen +minutes. Cool, add the balance of the mix, and freeze. + +Other nuts or fruits may be substituted for those mentioned in the +above receipts. + + +=72. Puddings.=--This product is usually very rich and is a combination +of cream, sugar, eggs, spices, various fruits and nuts. + +Receipt No. 1.--Nesselrode + + 32 lbs. 28 per cent cream + 10 doz. eggs + 10 lbs. sugar + 6 oz. vanilla + 4 lb. chopped walnut meats + 3 „ „ candied cherries + 3 „ „ „ fruits + 4 „ „ raisins + +Cook the egg-yolks with the cream. Beat the whites and add when partly +frozen. + +Receipt No. 2.--English Plum + + 32 lbs. 25 per cent cream + 8 doz. eggs + 12 lbs. sugar + 3 „ cocoa or chocolate + 5 „ assorted fruits that do not pulp + 2 „ seeded raisins + 3 „ dates + 4 „ walnut meats + 4 tablespoonfuls ground cinnamon + 1 „ ginger + 1 „ ground cloves + +Use the eggs as directed under receipt No. 1. Chop the fruits and nuts +fine. + +Receipt No. 3.--Fruit Pudding + + 32 lbs. 10 per cent cream + 8 „ whole condensed milk + 8 „ sugar + 5 oz. gelatine dissolved in part of cream + 2 lbs. chopped cherries + 2 „ „ raisins + 2 „ „ nuts + 1¹⁄₂ qts. sherry wine + +Soak the fruit overnight in sherry wine. + +Receipt No. 4.--Manhattan Pudding[19] + +[19] Ia. Bul. No. 123. + + 3 gals. 30 per cent cream + 10 doz. eggs + 12 lbs. sugar + 2 qts. orange juice + 1 pt. lemon juice + 4 lbs. walnut meats + 4 „ pecan meats + 4 „ cherries and assorted fruits + + +=73. Custards.=--A custard is usually made of milk, sugar, flavoring, +cornstarch or flour and the process is rather long. Quantities given +in receipts are for hand freezers. + +Receipt No. 1. + + 6 qts. milk + 3 lbs. sugar + 24 eggs + 12 tablespoonfuls cornstarch + 6 „ vanilla or to taste + +Put the milk over the fire in a farina or double water boiler. Moisten +the cornstarch with a little cold milk so that it can be added to milk +without lumping. When the milk is hot, add the cornstarch and stir +until it begins to thicken. Beat the eggs and sugar together until +light and then add them to the hot milk. Cook a few minutes, take from +the fire, flavor and cool and freeze same as ice-cream. + +Other flavors, as coffee or chocolate, may be made by substituting +these flavors for the vanilla. + +Receipt No. 2. + + 5 qts. milk + 1 qt. 30 per cent cream + 8 eggs + 2¹⁄₂ lbs. sugar + 6 tablespoonfuls flour + 1¹⁄₂ oz. of vanilla or to taste + +Follow directions given for No. 1. + +Receipt No. 3. + + 2 qts. 30 per cent cream + 4 „ milk + 3 lbs. sugar + 1¹⁄₂ qts. minute tapioca + Yolks of 4 eggs + 1 teaspoonful salt + 4 teaspoonfuls lemon extract + 2 teaspoonfuls rose extract + +Cook the tapioca in 2 quarts of milk for ten minutes, then add the +remainder of the milk, the sugar and the salt. Cook ten minutes longer. +Remove from the fire and add the egg-yolks well beaten. Then add the +extract, cool and freeze. When nearly done add the cream previously +beaten to stiff froth and finish freezing. A large number of receipts +for custard ice-cream may be found in the various cook-books. + + +=74. Ices and sherbets= are usually made either of water or milk, with +or without eggs and flavoring. Some kinds are frozen without agitation +and some beaten like ice-cream while freezing. + + +=75. Ices= are simply water sweetened, flavored and frozen. They become +grainy in texture very quickly. + +Receipt No. 1. + + 48 lbs. water + 20 „ sugar + 6 „ lemon juice + +Receipt No. 2. + + 48 lbs. water + 20 „ sugar + 2 „ lemon juice + 4 qts. pineapple juice + +Receipt No. 3. + + 48 lbs. water + 20 „ sugar + 2 „ lemon juice + 4 qts. finely pulped strawberries + + +=76. Water sherbet.=--The only difference between water sherbet and +ices is that eggs are used in the former and not in the latter. + +Receipt No. 1. + + 48 lbs. water + 16 „ sugar + 1 lb. lemon juice + 4 qts. grated pineapple (or pineapple juice) + 6 oz. gelatine in 4 lbs. water, if desired + 24 egg-whites beaten stiff and added when mixture is partly frozen + +Receipt No. 2. Same as No. 1 except replace the pineapple with grape +juice. + +Receipt No. 3. Use same mix as No. 1 except replace the pineapple with +orange juice. Boil the water and sugar to a clear sirup, then strain +and cool before freezing. + + +=77. Punches.=--The essential difference between ices, water sherbets +and punches, is the material used for flavoring. + +Receipt No. 1. + + 48 lbs. water + 20 lbs. sugar + 1 „ lemon juice + 1 qt. brandy and rum mixed + +Receipt No. 2. + + 48 lbs. water + 20 „ sugar + 1 lb. lemon juice + 1 qt. orange juice + 2 qts. wine + 4 oz. gelatin in part of water + +Receipt No. 3. + + 48 lbs. water + 20 „ sugar + 1 qt. lemon juice + 1 „ raspberry juice + 1 „ grape juice + cloves, cinnamon, allspice, and nutmeg to taste + + +=78. Milk sherbets.=--These are similar to water sherbets except milk +is used in place of water. + +Receipt: + + 48 lbs. milk + 16 „ sugar + 5 ozs. gelatine in 2 qts. water + 1 lb. lemon juice + 4 qts. fruit flavoring + 12 egg-whites beaten stiff and added after mixture is partly frozen + +Flavors: Orange, grape, cherry, pineapple, and strawberry. If lemon is +desired, use only 2 quarts of lemon juice with 1 quart of orange juice. + + +=79. Lacto[20].=--This is the only receipt in which sour milk is used. + +[20] Ia. Exp. Sta. Bul. No. 140. + +Receipt: + + 48 lbs. good starter just nicely coagulated + 18 „ sugar + 24 eggs, whites and yolks beaten separately + 2 qts. grape juice + 1¹⁄₂ qts. lemon juice + +Mix in the order given in the formula. Other flavors may be substituted +for the grape juice. + + + + +CHAPTER VII + +_EQUIPMENT_ + + +The size and kind of equipment will depend on the extent of the +business and the available capital. It is not considered economical to +install a mechanical refrigerating system unless at least seventy-five +gallons of ice-cream are manufactured a day. + +Certain factors should be considered when purchasing machinery; the +construction and adaptability of the machine for the type of work it is +intended to do; the ease of making repairs; the ease of cleaning; the +durability of the machine; the protection to gearing from ice and salt. + +[Illustration: FIG. 8.--Hand freezer with tub and can cut away showing +ice and salt mixture and beaters and scrapers in the can.] + +[Illustration: FIG. 9.--Hand freezer with fly wheel, using salt and ice +mixture for freezing. The capacity is five gallons.] + +[Illustration: FIG. 10.--Power driven tub and can freezer, using a salt +and ice mixture. The can, dasher, cover and gears are shown removed.] + +[Illustration: FIG. 11.--Horizontal brine freezer attached to salt and +ice brine box. The pump is behind the box.] + + +=80. Freezers.=--The general principle of the ice-cream freezer is +the same in all makes; however, the application may be varied. The +unfrozen ice-cream or mix is placed in a container, usually called the +freezing-can. This can is surrounded by the freezing material, either +cold circulating brine or an ice and salt mixture. In the can is the +beater or dasher. To this is attached two scrapers which, when rotated, +scrape the frozen ice-cream from the sides. The can itself may revolve +or stand still, depending on the type of freezer. The dasher may +revolve or stand still, depending on whether the can revolves or stands +still. In most freezers there is another part of the dasher which +revolves to help beat up the ice-cream. The freezers may be divided +into two general classes. The one class consists of a tub and can in +which an ice and salt mixture is used between the tub and can. This +type of freezer is made to run by hand or mechanical power, and varies +in size from a few pints to ten gallons. The largest hand size is +usually five gallons; these have a flywheel. The types of hand freezers +are shown in Figs. 8 and 9. A power-driven tub and can freezer, using +a salt and ice mixture in the tub for freezing, is shown in Fig. 10. +The other class is the brine freezer. In this, cold brine is forced +around the freezing-can. The freezer runs by mechanical power, either +belt-driven or directly connected to an electric motor. The brine +may be made from an ice and salt mixture, or it may be cooled by an +artificial refrigerating system. There are two general types of brine +freezers. One has the freezer in a horizontal position and the other +in a vertical. Advantages are claimed for both. The arrangement of +brine freezers when the brine is obtained from a salt and ice mixture +is shown in Figs. 11 and 12. The brine as it comes from the freezer is +sprayed over the ice and as it trickles through is cooled again. It is +then pumped around the freezer again. The ice is held in the box by +means of a heavy wire screen; otherwise, it would clog the pump. + +[Illustration: FIG. 12.--Vertical belt driven brine freezer connected +to ice and salt brine box. Pump is shown between freezer and box.] + +[Illustration: FIG. 13.--Perfection brine freezer, direct motor drive.] + +Some of the types of brine freezers in common use are shown in Figs. +13, 14, 15, and 16. Most of these may be either belt or direct +motor-driven. The usual size is ten gallons. In some cases they have +been made larger but these are not in common use. It is the usual +practice to have a supply tank just above the freezer-can which can +be filled, while one can is freezing. The mix for the next freezer is +placed in this supply can and will then run quickly from it into the +freezer. + +[Illustration: FIG. 14.--Progress vertical belt drive brine freezer.] + +[Illustration: FIG. 15.--Emery Thompson vertical direct motor drive +brine freezer.] + +Another brine freezer is the disc which may be used either as a batch +or continuous freezer. A front view of this is shown in Fig. 17. The +supply can is seen on one side and the delivery spout on the other. A +glass plate over the freezing discs allows the process to be seen at +any time. A side view is seen in Fig. 18, showing the brine box and +pump. The freezing discs are illustrated in Fig. 19, also the scrapers +to remove the ice-cream from the discs and the screw to force the +ice-cream along. When used as a batch freezer, the ice-cream is drawn +from the bottom. + +[Illustration: FIG. 16.--Fort Atkinson horizontal belt drive brine +freezer.] + +[Illustration: FIG. 17.--Disc brine freezer either continuous or batch.] + +[Illustration: FIG. 18.--Side view of freezer shown in Fig. 17. +Arrangement of brine tank and pump are shown.] + +[Illustration: FIG. 19.--Freezing discs of freezer shown in Figs. 17 +and 18. The scrapers for removing the ice-cream from the discs and the +screw to force it out of the delivery spout are shown.] + +[Illustration: FIG. 20.--A pasteurizer or ripener used as an ice-cream +mixer. Strips are attached to the coils to prevent the settling of the +sugar on the bottom.] + + +=81. Mixers.=--When large quantities of ice-cream are made, a +container of some sort, with a mechanical agitator to stir the +contents, is used to mix the ice-cream ingredients. Some of these +mixers are provided with coils in which water or brine may be +circulated to control the temperature. Some may be operated as a +pasteurizer. An ordinary cream ripener might be used as a mixer if +the sugar could be prevented from settling to the bottom. Some +manufacturers have accomplished this by placing a strip of iron on +the coils which will reach almost to the bottom of the ripener. Such +an arrangement is shown in Fig. 20. An ordinary starter can might be +utilized as a mixing vat or can. (Fig. 21.) + +[Illustration: FIG. 21.--Minnetonna starter can or ice-cream mixer.] + +A number of ice-cream mixers are commonly used, as shown in Figs. 22, +23, and 24. Most of these have coils which carry cold water or brine +to cool the mix. In some these coils act as the agitator and in others +they are placed in a jacket around the mixer. In order to keep the +materials properly mixed if the coils themselves do not serve as the +agitator, there is some form of mechanical agitator. These agitators +may be belt or direct motor-driven. + + +=82. Gelatine kettles.=--In most plants where much ice-cream is made, +a special kettle is employed to dissolve the gelatine. (Fig. 7.) This +consists of a copper steam-jacketed kettle. With this the gelatine +and water may be heated without danger of burning. The size of these +kettles depends on the amount of gelatine used. + + +=83. Hardening the ice-cream.=--Some means of keeping the ice-cream +cold after it is removed from the freezer must be provided. This may be +a specially cooled room known as a hardening room or the ice-cream may +be packed in a mixture of salt and ice. These methods of hardening will +be discussed later. + +[Illustration: FIG. 22.--Alaska ice-cream mixer. The side is cut away +showing the coils and insulation. The mechanical agitator is seen at +the bottom. By means of the tight fitting cover and the air pump, the +mix may be forced to the freezer by air pressure.] + +[Illustration: FIG. 23.--Wizard ice-cream mixer.] + +[Illustration: FIG. 24.--Emery Thompson ice-cream mixer.] + + +=84. Packing-cans.=--In order that the freezer may be kept in use, +as soon as the ice-cream is sufficiently frozen, it is removed and +placed in other cans to harden. These are known as packing-cans (Fig. +25) and are made of heavy iron and tinned and fitted with a cover. The +cans vary in size from one quart to five gallons and the ice-cream +is hardened and delivered in these. When ready for delivery, these +pack-cans are placed in tubs which should be a little higher than the +pack-can to allow for ice over the top. There should be a space also of +2-4 inches between the sides of the can and the tub to allow for the +ice and salt. The ice-cream may be packed in small oblong containers +known as bricks, usually containing one or two pints. + +[Illustration: FIG. 25.--Two types of ice-cream packing-cans.] + +The ice-cream may be hardened in a larger brick mold which will make +several smaller bricks. When hard the ice-cream is cut into the smaller +bricks, wrapped in parchment paper and placed in a paper carton. This +is the usual method of handling brick ice-cream. Several different +layers may be placed in each brick. + + +=85. Ice crushers.=--The ice must be broken into small pieces for +freezing or packing the ice-cream. This may be done by hand with an ice +spud or cracker. (Figs. 26 and 27.) If much ice is to be cracked or +crushed, a mechanical crusher should be used. (Fig. 29.) The small ones +run by hand power but turn rather hard. The crushers run by mechanical +power are more frequently seen in ice-cream plants. These vary in size. + +[Illustration: FIG. 26.--Ice spud.] + +[Illustration: FIG. 27.--Ice cracker.] + +[Illustration: FIG. 28.--Perforated ice shovel.] + +[Illustration: FIG. 29.--Ice crusher with tight and loose pulley for +mechanical power. The teeth or picks on the drum may be seen.] + +[Illustration: FIG. 30.--The perfection ice-cream can-washer and +sterilizer.] + + +=86. Ice-cream can-washers.=--The washing of the ice-cream pack-cans +by hand in an ordinary sink consumes much time. In the larger plants +an ice-cream can-washer is used. This consists of sprays of water and +revolving brushes. The cans are usually brushed both on the inside and +outside. Some types of ice-cream can-washers and sterilizers are shown +in Figs. 30 and 31. When washed, the cans should be sterilized. + +[Illustration: FIG. 31.--Fort Atkinson ice-cream can-washer and +sterilizer.] + +[Illustration: FIG. 32.--De Laval centrifugal emulsor.] + + +=87. Emulsors, creamers, and homogenizers.=--These machines vary +considerably in mechanical construction as shown in Figs. 32, 33, +34, 35, and 36. Nevertheless, the making of cream from butter, milk +powder, condensed milk or skim-milk is accomplished by each machine. +The force used to break up and mix the materials varies with the +different machines. One type which uses steam as the force to break up +the material is illustrated by Fig. 33. The amount of steam pressure +required varies with the different makes. Another type of machine which +uses centrifugal force as the means of breaking up the materials is +illustrated by Figs. 32 and 36. In this type, the materials are broken +up or mixed by being thrown by centrifugal force through a very small +opening or narrow space. The other type of machine, which is operated +by valve pumps, is illustrated in Figs. 34 and 35. By means of the +pumps the materials are forced through a very small opening against +some hard material. This machine, known as a homogenizer, breaks the +materials into very small particles; for example, cream that has been +homogenized cannot be re-churned in butter because of this. A good +quality of cream may be made from any of the following combinations +according to the DeLaval Separator Company: + +Skim-milk powder--water--butter--(preferably uncolored and unsalted). + +Whole-milk powder--water--butter. + +Condensed skim-milk--water--butter. + +Condensed whole milk--water--butter. + +Skim-milk--skim-milk powder--butter. + +Skim-milk--condensed skim-milk--butter. + +Whole milk--skim-milk powder--butter. + +Whole milk--condensed skim-milk--butter. + +[Illustration: FIG. 33.--Perfection cream-maker and emulsifier.] + +[Illustration: FIG. 34.--Progress homogenizer.] + +[Illustration: FIG. 35.--Gaulin homogenizer.] + +One should never lose sight of the fact that the better the quality of +the materials used, the better will be the flavor of the cream. It is +impossible to make first-quality cream from poor materials. The whole +milk and skim-milk must be clean and sweet. Skim-milk powder should be +dry, loose, and fluffy. The condensed milk should be clean flavored +and fresh. Off-flavored condensed milk or milk that is grainy or gritty +should never be used. The manufacturers of the various machines send +specific directions for their operation. To insure success, these +directions should be followed carefully. It is the usual practice +first to put the milk powder into solution, then to cut the butter +into small pieces and put it into the milk. If skim-milk is used, the +butter is put directly into it. The milk and butter are then heated to +a temperature high enough to melt the butter, usually 130° to 150° F. +It is then run into the machine. Because of the tendency of the butter +to rise to the top, the materials must be kept in constant agitation +until run into the machine. Otherwise, the butter would be at the top +and would not run into the machine until the other materials had all +run through. + +[Illustration: FIG. 36.--Sharples centrifugal emulsor.] + +Some makers emulsify or homogenize the whole ice-cream mix. In this +case, the flavoring extracts and fruits are not added until after the +mix has been through the machine. It is the general opinion that the +emulsifying or homogenizing of the whole mix makes a smoother body and +texture in the product. + +Advantages in the use of emulsors and homogenizers: + + 1. Smoother body in ice-cream. + + 2. Less time required for ageing cream, especially pasteurized. + + 3. Not necessary to carry so large a stock of raw materials. + + 4. Ice-cream of more uniform composition. + +Disadvantages in the use of emulsors and homogenizers: + + 1. The disadvantage in the use of the homogenizer is in its abuse + since a homogenized cream will appear richer than it really is. There + is a tendency to use less solids, especially fat. + + 2. Danger of using inferior materials. + + 3. If cream is not needed for ice-cream and has been homogenized, it + cannot be churned. + + +=88. Cost of equipment.=--Because of the constant change in price, it +is impossible to give even estimates of cost of equipment. The price +might be correct to-day and incorrect to-morrow. The cost of equipment +based on the gallonage of ice-cream is usually higher for the smaller +plant. In order to obtain accurate prices, the various dairy supply +houses should be consulted. + + + + +CHAPTER VIII + +_REFRIGERATION AS APPLIED TO ICE-CREAM-MAKING_ + + +In the making of ice-cream, refrigeration is necessary. In the +following discussion only the underlying principles as applied to +operation will be taken up. The details of construction are discussed +by refrigerating engineers in various text-books.[21] + +[21] Audels, “Answers on refrigeration,” 700 pages; Cooper, Madison, +“Practical cold storage,” 800 pages. + +Refrigeration is the interchange of heat units. The cooling for +ice-cream-making may be obtained either from natural ice or from +mechanical refrigerating machines. These will be discussed under their +separate heads. + + +=89. Terms used.=--In order easily to comprehend the principles of +refrigeration, it is necessary to understand the terms used.[22] + +[22] Bowen, John T., “The application of refrigeration to the handling +of milk,” U. S. Dept. Agr. B. A. I., Bul. 98. + +“British thermal unit.--A British thermal unit (B. T. U.) is the +quantity of heat required to raise 1 pound of pure water 1 degree +Fahrenheit, at or near its maximum density, 39.1° F. Some authorities +consider a British thermal unit as the heat required to raise 1 pound +of pure water from 61° to 62° F. For practical purposes, however, it +may be considered the heat required to raise the temperature of 1 pound +of water 1 degree Fahrenheit. + +“Sensible heat.--Sensible heat is the heat that may be felt by the hand +or measured by a thermometer. + +“Latent heat.--Latent or ‘hidden’ heat is the heat which is expended +in molecular work of separating the molecules of the substance and can +not be measured by a thermometer. Every substance has a latent heat of +fusion, required to convert it from a solid to a liquid, and another, +latent heat of vaporization, required to convert it from a liquid to +a gas or vapor. Thus, if heat is applied to a pound of ice at 32° F. +it will begin to melt, and no matter how much heat is applied, the ice +will not get any hotter. After every particle of ice has melted, we +will have 1 pound of water at 32° F., the same temperature as the ice +before heat was applied. Experiments have shown that it requires 144 +British thermal units to melt 1 pound of ice at 32° F. into water at +32° F.; hence the latent heat of fusion of ice is said to be 144. + +“If heat is applied to 1 pound of water at 212° F., the water will +remain at 212° F. under atmospheric pressure until all of it has been +evaporated into steam at 212° F. This has been found to require 970.4 +British thermal units; hence the latent heat of vaporization of steam +at atmospheric pressure is said to be 970.4 B. T. U. + +“Specific heat.--The specific heat of a substance may be defined as the +ability of that substance to absorb heat compared to that of water. +Water being one of the hardest of all substances to heat, its specific +heat is taken at unity. A better understanding of latent and specific +heat may be had by studying the diagram in figure 42 which shows +graphically the relation of heat to temperature. + +“Ton refrigeration.--Refrigeration, or ice-melting capacity, is a term +applied to represent the cold produced, and is measured by the latent +heat of fusion of ice, which is 144 B. T. U. per pound. In other words, +it is the heat required to melt 1 pound of ice at 32° F. into water +at the same temperature. The capacity of a machine in tons of ‘ice +melting’ or ‘refrigeration’ does not mean that the machine would make +that amount of ice, but that the cold produced is equivalent to the +melting of the weight of ice at 32° into water at the same temperature. +Therefore 1-ton refrigeration is equal to 144 × 2,000, or 288,000 B. +T. U. A 1-ton refrigerating machine is a machine that has a capacity +sufficient to extract from an insulated bath of brine 200 B. T. U. per +minute, 12,000 B. T. U. per hour, or 288,000 B. T. U. per 24 hours. + +“Absolute pressure.--Absolute pressure is pressure reckoned from +a vacuum. Pressure gauges in general use are arranged to indicate +pressure in pounds per square inch above atmospheric. To convert gauge +pressure to absolute pressure, 14.7 pounds, the weight per square inch +of air pressure at sea level, must be added.” + + +NATURAL ICE + +Only in the cold or northern latitudes can a supply of natural ice be +obtained. In the warm regions a refrigerating machine or ice made by +an artificial refrigerating system must be used. The harvesting of ice +is a very simple process, yet it involves a large number of details. +Success in obtaining a crop of ice requires careful attention to each +detail. + + +=90. The ice field.=--It is important that the water from which the +ice is to be made be free from contamination. If weeds grow in the +pond in the summer, they should be removed in the fall. If green spawn +or algæ grow profusely, they can be eliminated by the use of copper +sulfate.[23] The crystals may be placed in a cloth sack, which is +hung to a pole and trailed through the water until the salts are +dissolved. One or two treatments of the sulfate in the season, at +the rate of 1 pound to 100,000 gallons (13,000 cubic feet) of water +will be sufficient to keep down such growth and make the water clear +and pure. The area of the ice field or pond should be large enough +to fill the ice-house at a single cutting, some allowance being made +for waste. The water should be deep enough so that there will be at +least from eighteen inches to two feet under the ice at the time of +harvesting. Snow often interferes with the ice formation. If the ice +is thin, and the fall of snow heavy, the latter may sink the ice. If +the snow remains on the ice, it acts as an insulator and so prevents +the freezing. The snow may be handled in either of two ways; it may be +scraped off the ice by hand or with a horse scraper, or the snow may be +soaked with water. In the latter practice, there is danger of a crust +forming and so preventing the formation of ice and hindering future +scraping. + +[23] Corbett, L. C., “Ice houses,” U. S. Dept. Agr., Farmers Bul. 475, +1915. + + +=91. The ice-house.=--The main essentials of a good ice-house are +insulation, ventilation, and drainage. The house should be so located +that there will be good drainage. If proper drainage is not provided, +the water acts as a conductor of heat and so causes the ice to melt +faster. It is desirable, but not necessary, that the ice-house have a +north exposure and shaded with trees to keep off the heat of the sun. +It should be located as near the place where the ice will be used as +possible. There is a wide range of variation in type of construction +and cost of materials in the erection of a satisfactory ice-house. The +walls may be insulated so that the ice is simply piled in the house. +This is the most expensive type of construction. In contrast to the +insulated house, a bin may be built and the cakes of ice piled close +together in it so that there will be a space about one foot to eighteen +inches around the sides between the ice and the bin. This space should +be filled with sawdust or hay and an equal amount placed over the top, +which acts as an insulator. This is the cheapest form of construction +and is somewhat wasteful since the top of the pile is exposed to the +direct rays of the sun and the rains. The usual type of ice-house is +a form of construction between the two extremes mentioned above. It +consists of a cheap board frame to hold the insulation on the sides and +a roof. The gables should be partly open to give a circulation of air. + +A cubic foot of ice weighs about 58 pounds and requires about 35 +cubic feet for a ton. Allowance for the spaces between the cakes of +ice should be made when figuring the capacity of the house. The usual +practice is to figure from 43-46 cubic feet for each ton of ice. + + +=92. Harvesting and storing.=--Ice is not usually harvested until at +least 8-12 inches thick. This will depend on the location and the +season. The size of the cakes vary, but the usual sizes are 22 × 32 +inches; 20-22 × 28; 22 × 42-44. The cakes of ice may be sawed with a +hand-saw. (Fig. 37.) + +On a large field, the ice may be cut with an ice-plow drawn by horses. +(Fig. 38.) On this plow is a marker to show where the next cut should +come. Thus if the first cut is straight, a straight mark will be made +to be followed for each succeeding cut. The ice-plow does not cut +entirely through the ice, but it should be adjusted to cut nearly +through. This will make the breaking off of the cakes easy. If the +field is large enough, it is usually plowed each way. This cuts the +ice into cakes. Therefore, after plowing all that is necessary is to +separate the cakes. This is accomplished by breaking or splitting with +a splitting-fork. (Fig. 39.) On a small field, the ice is sometimes +plowed only one way. In this case the cakes are sawed off with the +hand-saw. + +[Illustration: FIG. 37.--Hand ice-saw.] + +[Illustration: FIG. 38.--Ice-plow with marker.] + +Either a perpendicular or inclined elevation with their conveyors +should be used to put the ice into the house. Only regular shaped +cakes should be stored, all broken ones being rejected because they do +not pack closely, hence allow too much waste and air space. The cakes +should be packed closely together and yet allow air circulation. In +order to secure this, it is best to run the rows of cakes one way in +one tier, the other way in the next tier and so on. Each tier should +be planed smooth before the next is placed on it. This may be done +by a large planer on the ice incline or by hand in the house. The +insulation should be put around the sides as the house is filled. When +all the ice is in the house, the insulation, either hay or sawdust, +should be immediately placed over the top. The ice should be watched +and if the hay or sawdust has settled so that the ice is exposed to +the air, more should be added. It is best to fill the house when it is +freezing temperature. If it is thawing the cakes of ice will have water +on them, later this will freeze and it will be almost impossible to +remove the cakes without breaking them. When taking the ice out, each +tier should first be removed before the one below is disturbed. After +each removal of ice the covering over the top should be replaced. + +[Illustration: FIG. 39.--Splitting fork.] + + +=93. Amount of ice needed.=--It is difficult to know exactly how much +ice to store to meet the needs of the summer. Some ice goes farther +than others; some years there is more waste than others. The following +figures compiled by the “Ice Cream Trade Journal” will give a fair idea +of the amount required to a gallon of ice-cream: Amount of ice used for +100 gallons, 1,928 pounds. This was divided as follows: freezing, 614 +pounds; hardening and storing, 914 pounds; shipping, delivering, and +icing cabinets, 400 pounds. + + +=94. Use of ice and salt mixture.=--Under normal conditions ice melts +slowly. In order to obtain a quick change of temperature and one below +that of the ice, a salt and ice mixture is used. Bowen[24] gives the +following discussion of cooling by salt and ice mixtures: “When two +solid bodies, as salt and ice, mix to form a liquid a certain amount +of heat becomes latent, called the latent heat of solution. Since this +latent heat is taken from the mixture itself the temperature falls +correspondingly. The temperature obtained by a salt and ice mixture +depends principally on the relative proportions of the mixture, and +to a less extent on the rate at which the heat is supplied from the +outside, the size of the ice lumps and salt particles, and the amount +and density of the resulting brine. Hence it is impracticable to give +other than approximate temperatures with fixed ratios of salt and +ice. The following curve (Fig. 40) shows the approximate temperature +obtained with different proportions of salt and ice. + +[24] Bowen, John T., “The application of refrigeration to the handling +of milk,” U. S. Dept. Agr. B. A. I., Bul. 98. + +[Illustration: FIG. 40.--Approximate temperatures obtained with +different proportions of ice and salt.] + +“One pound of ice, in melting, absorbs 144 B. T. U. This is known as +the latent heat of fusion of ice. Salt in dissolving also absorbs heat, +called the latent heat of solution, which varies in amount, depending +on the density and temperature of the resulting brine. + +“The heat of solution of salt in water at 32° F. varies from 58 to 16 +B. T. U., depending on the final strength of the brine obtained. + +“The following curve (Fig. 41) shows the amount of refrigeration +available per pound of ice and salt mixture. The figures were +calculated from the melting of ice at 32° F. into a liquid at the same +temperature. If, however, the salt is added to the ice at a temperature +varying from 32° F. or, if the resulting brine is allowed to escape at +a temperature other than 32° F., the amount of available refrigeration +must be corrected accordingly. These corrections are determined by +multiplying weights, in pounds of salt and brine, by their respective +specific heats and by their difference in temperature from 32° F. The +specific heat of dry salt may be taken as 0.214, as the specific heat +of salt brine varies with its density. + +[Illustration: FIG. 41.--Refrigeration available with different +percentages of salt.] + +“Usually salt when added to ice is of a higher temperature than that of +the ice; consequently the correction for its heat above 32° F. must be +subtracted from the available refrigeration shown by the curve, Fig. +41; and if the brine is allowed to escape at a temperature below 32° +F. the refrigeration lost in the discharge brine must be subtracted, +while, on the other hand, if the discharge brine is at a temperature +higher than 32° F. the correction must be added. + +“If given amounts of ice and salt, at a temperature of 32° F. are mixed +together and the mixture supplied with sufficient heat to melt the +ice and dissolve the salt and raise the temperature of the resulting +brine to the original temperature of 32° F., then the total amount of +heat absorbed by the reaction will be the sum of the latent heat of +the ice and the heat of solution of the salt to form the resulting +brine of the density which will result from the particular proportion +of salt and ice chosen. As an example, under the foregoing conditions, +if 100 pounds of dry salt are added to 900 pounds of ice the total +available refrigeration is 1,000 × 133 = 133,000 B. T. U. The available +refrigeration per pound of mixture, 133 B. T. U., is taken from the +curve in Fig. 41. If the salt added is at a higher temperature than +32° F., say 60° F., then the available refrigeration will be 133,000 +- [100 × 0.214 (60 - 32)] = 132,401 B. T. U., or 132.4 B. T. U. per +pound of mixture. If the resulting brine is allowed to escape at 25° +F., the available refrigeration is 133,000 - [1,000 × 0.892 (32 - 25)] += 126,756 B. T. U., or 126.7 B. T. U. per pound of mixture. Or, in +other words, there is lost in the first case 100 × 0.214 (60 - 32) = +599 B. T. U., and in the second case, 1,000 × 0.892 (32 - 25) = 6,244 +B. T. U., or a total loss, if the salt is added at 60° F. and the brine +allowed to escape at 25° F., of 599 + 6,244 = 6,843 B. T. U. Under +these conditions the available refrigeration is 133,000 - 6,843 = +126,157 B. T. U., or 126 B. T. U. per pound of mixture.” + + +MECHANICAL REFRIGERATION + +A large number of small ice-cream plants do not use mechanical +refrigeration, but natural ice. It is not considered economical +either in labor or cost to attempt to employ ice if seventy-five or +more gallons of ice-cream are made a day. The size of the mechanical +refrigerating machine varies, but the underlying principles are the +same. + + +=95. Principles of mechanical refrigeration.=--Bowen gives the +following concise but plain description of these principles:[25] + +[25] Bowen, J. T., “The application of refrigeration to the handling of +milk,” U. S. Dept. Agr. B. A. I., Bul. 98. + +“When a solid or a liquid changes its state or condition, as when a +solid is converted into a liquid or a liquid into a gas or vapor, +the change of state or condition is in each case accompanied by the +absorption of heat. This absorption of heat, as previously explained, +is called ‘Latent Heat’; that is, heat that cannot be measured by a +thermometer; and in order to transfer a substance from one state to +another it is only necessary to supply or extract heat. For instance, +if we take 1 pound of ice at zero temperature, Fahrenheit scale, and +apply heat, the temperature will rise until it reaches 32°. If we +continue the application of heat, the ice will begin to melt, and after +we have supplied sufficient heat the 1 pound of ice will have changed +to water at 32° F., the same temperature at which the ice commenced +to melt. If the application of heat is continued the water will grow +warmer, but at a slower rate. It now takes about double the amount of +heat to raise the 1 pound 1 degree as water that it did to raise the 1 +pound 1 degree as ice. In other words, the specific heat of water is +approximately double that of ice. + +“When sufficient heat has been added to raise the 1 pound of water to +a temperature of 212° F., another critical point is reached at which +further application of heat to the water, under atmospheric pressure, +will not increase its temperature, but changes it into steam at a +temperature of 212°. The relation of heat to temperature is shown in +Fig. 42. + +“It will be noted from Fig. 42 that to raise the temperature of the 1 +pound of ice from zero to the melting point (32° F.) 16 B. T. U. were +expended; in melting the ice, 144 B. T. U.; in raising the water to the +boiling point, 180 B. T. U.; and to evaporate the water, 970.4 B. T. U. +If the operation is reversed, the heat being extracted instead of being +added, the curve will follow backward on itself to the starting point. + +“The latent heat of fusion and the latent heat of vaporization are +represented on the diagram by the two lines parallel to the horizontal +base line, the length of the lines representing to scale the amount +of heat expended in molecular work in separating the molecules of the +substances. Starting from the left, the rising lines represent the +heat required to raise the temperature of the ice, water, steam at +constant volume, and steam at constant pressure, respectively.” + +[Illustration: FIG. 42.--Diagram showing relation of heat to +temperature.] + + +=96. Materials used in mechanical refrigerating systems.=--“The same +law applies to liquified anhydrous ammonia, carbon dioxid and sulphur +dioxid, which are the substances most commonly used in commercial +refrigerating machines. These liquids are extremely volatile, their +change of state takes place very rapidly, and their latent heat is +absorbed at a corresponding rate. Their boiling point is sufficiently +low, under atmospheric or other conveniently produced pressure, to give +the temperature desired. Although the same principles underlie the use +of all such fluids, their physical properties vary, and consequently +demand different treatment in order to produce the best results. + +“The theoretical requirements of a good refrigerant are: A low boiling +point at ordinary pressure, a large latent heat of vaporization, and +a small specific volume. A low boiling point is desirable, because +it makes operation possible with comparatively low pressure in all +parts of the system; therefore, the machines and accessories may be +of lighter construction, with smaller loss of gas by leakage. As the +latent heat of vaporization is, to a certain extent, a direct measure +of the cooling effect, it is obvious that the greater the heat of +vaporization the better the refrigerant. The specific volume of the +refrigerating agent determines the volume of the cylinders of the +compressor, consequently the size and weight of the machine. + +“In comparing the three refrigerating agents which are considered +applicable to the dairying industry, viz., ammonia, carbon dioxid, and +sulphur dioxid, it will be noted by referring to tables giving the main +characteristics of the agents that, assuming the limits of operation +are between 5° F. and 85° F., the absolute pressures are: Ammonia from +27 to 175 pounds, carbon dioxid from 290 to 1,000 pounds, and sulphur +dioxid from 9 to 65 pounds. Taking the boiling points of the liquids at +the temperature at which the liquid boils under atmospheric pressure, +it will be noted that there is a wide difference in their boiling +points as well as their latent heats of vaporization. Ammonia boils +at 28.5° F. below zero and has a latent heat of vaporization of 572.8 +B. T. U. Carbon dioxid boils at 110° F. below zero and has a latent +heat of vaporization of 140 B. T. U. at a pressure of 182 pounds per +square inch absolute. The latent heat at atmospheric pressure is not +definitely known. Sulphur dioxid boils at a temperature of 14° F. and +has a latent heat of vaporization of 162.2 B. T. U. + +“For practical purposes the value of a refrigerant depends upon its +boiling point, its latent heat of vaporization, and upon the pressure +at which it can be used. + +“To maintain a zero temperature with ammonia as the refrigerant an +absolute pressure of 30 pounds per square inch is required in the +evaporating coils; with carbon dioxid, 310 pounds absolute; and for +sulphur dioxid, 10 pounds. + +“Ammonia has a much greater latent heat of vaporization and the working +pressures are not excessive, but it has the disadvantage that it +corrodes brass or any other copper alloy; consequently only iron or +steel can be used in the construction of those parts of the machine +with which the agent comes in contact. The pressures of carbon dioxid +are so high as to cause trouble in keeping the stuffing box and joints +tight. A relief valve is often placed in the high-pressure side of +the system in order to protect it from excessive high pressures. It +is noncorrosive, nonexplosive, and is not dangerous to life when +diluted with air. The high pressures necessary, combined with the +small specific volume of the gas, make it suitable for use with a very +compact machine. As the lower pressure of sulphur dioxid is below the +atmospheric, any leakage of air will be into the system and will cause +corrosion of the metal by forming sulphurous acid. The low pressures +required in using sulphur dioxid as a refrigerant in connection +with its large specific volume makes a large and cumbersome machine +necessary. The ratios of the volumes of the cylinders necessary for a +given capacity of machine, taking that of carbon dioxid as one, are +approximately as follows: Carbon dioxid 1, ammonia 4.4, sulphur dioxid +13.” + + +=97. Operation of refrigerating machines.=--The refrigerating material +commonly used in ice-cream plants is ammonia. There are two types of +ammonia machines, the compression and the absorption systems. + + +=98. The compression system.=--The following, Fig. 43, shows the +simplest compression system of refrigeration. The liquid ammonia in the +small container is allowed to evaporate but it really boils. In order +to boil or to change from a liquid to a gas, it must absorb heat. This +heat is taken from the surrounding material, in this case brine. This +cools the brine in the container in which the vessel of ammonia is +placed. In this case, there is no control of the rate of evaporation of +the ammonia. + +[Illustration: FIG. 43.--Simplest compression system of refrigeration.] + +An arrangement by which the evaporation or escape of gas can be +controlled is shown in Fig. 44. The flow of liquid is regulated by +an expansion valve and the liquid is carried into a brine tank or +refrigerating room and from the coil of pipe in there gas is allowed +to escape in the atmosphere. The change from a liquid to a gas in this +coil of pipe cools the surrounding substance, either brine or air. This +is the usual arrangement of the compression system; the remainder of +the system is to return the evaporated liquid or gas back to a liquid +in the ammonia tank. + + +=99. Parts of a compression system.=--The functions and principal parts +of a compression system of refrigeration are as follows: + +_Compressor._--This is a specially designed valve pump. It takes the +gas from the evaporating coils, compresses it and forces it into the +condensing coils. This reduces its volume and produces heat. + +[Illustration: FIG. 44.--Compression system of refrigeration in which +the flow of liquid is regulated by the expansion valve. The liquid +changes to a gas in the coil of pipe, thereby cooling the brine. The +gas finally passes off into the atmosphere.] + +_Oil-traps._--In the compressor, there is danger of some oil becoming +mixed with the ammonia. The purpose of the trap is to separate the oil +from the ammonia. It is usually placed next the compressor. + +_Condensing coils._--This consists of a double coil of pipe, one within +the other. Cold water is circulated in the inner pipe and the ammonia +in the space between the inner and outer pipe. In the condensor the +heat is taken up by the water and the ammonia again becomes a liquid. + +_Ammonia receiver or storage tank._--From the condensing coils, the +liquid ammonia passes into a receiving or storage tank until wanted for +use again. + +_Expansion valve._--It is by means of this valve that the evaporation +of the ammonia is regulated or, in other words, the rate of flow of the +ammonia from the receiving tank is regulated by this valve. + +_Evaporating coils._--These coils are usually located in the material +to be cooled, ordinarily the air of the refrigerator or a brine tank. +In these coils, because of the reduced pressure, the ammonia liquid +evaporates or boils and in doing so takes up heat. This, as has been +explained before, causes the cooling. From the evaporating coils the +ammonia gas goes back to the condensor. This makes a complete circuit +for the ammonia. + + +=100. Operation of direct expansion compression system.=--The +following diagram, Fig. 45, shows the complete system of direct +expansion refrigerating. When the evaporation coils are placed in the +refrigerator and the heat is taken directly from the air, it is known +as the direct expansion system. + +[Illustration: FIG. 45.--Complete system of direct expansion +refrigerating machine.] + +The liquid ammonia passes from the ammonia receiver (R) through the +expansion valve (X) into the evaporating coils (E). Here the ammonia +changes from a liquid to a gas and in so doing takes up heat from +the refrigerator. The ammonia gas passes to the compressor (C). From +the expansion valve to the compressor is what is usually known as +the low pressure side because here the pressure is reduced in order +that the ammonia can boil or evaporate. For this reason the expansion +valve is sometimes called the reducing valve. The gas is compressed +in the compressor (C), then passes through the oil-trap (S) where +the oil is taken out and then through the condensing coils (W) where +the heat is absorbed and the gas changed to a liquid and back to the +ammonia receiver (R). From the compressor to the expansion valve is +what is known as the high side because of the pressure caused by the +compression. + + +=101. Location of evaporating coils.=--As explained above, the location +of the evaporating or expansion coils in the refrigerator so that the +heat is taken directly from the air is known as the direct expansion +method of refrigeration. In order to keep a refrigerator cold with this +method, it is necessary to run the compressor almost continuously. +In some cases the evaporating or expansion coils are placed in brine +tanks. The heat is then taken from the brine which in turn cools the +air. By the use of the brine tanks, the compressor may be stopped and +the cold brine will tend to maintain a more uniform temperature in the +refrigerator while the compressor is not running. + +A combination of the direct expansion and brine storage tanks is shown +in Fig. 46. This is a common arrangement in refrigerators where a low +temperature is desired and it is not economical to run the compressor +continuously. The brine storage tanks are sometimes called congealing +tanks. + +In some cases it is desirable to have refrigeration in some place where +it is not possible to use either the direct expansion or the brine +storage system; for example, to freeze ice-cream. In this case the +expansion coils are located in a brine tank and the cold brine pumped +to the place where refrigeration is desired. Such an arrangement is +shown in Fig. 47. The brine flows from the tank (T) in the refrigerator +to the pump (P). It is then pumped through the ice-cream freezer +(I) and back to the brine tank. The latter may be separate from the +refrigerator and contain cans of water for the making of artificial +ice. Most plants make artificial ice for packing the ice-cream for +delivery. + +[Illustration: FIG. 46.--Combination of direct-expansion and brine +storage tanks. This is the same system as shown in Fig. 45 with the +brine tank T added in the refrigerator.] + + +=102. Notes on operating compression system.=--In order to operate +a refrigerating machine economically, certain factors must be given +constant attention. When ammonia is passing through the expansion +valve, it should be covered partially with frost or the part where +the pressure is reduced will be frosted as will the pipe leading +from it into the refrigerator. This cannot be prevented. The proper +adjustment of the expansion valve is very important. If too wide open, +the flow of liquid will be too rapid, it will not all vaporize in the +evaporating coils and so will take heat from the air after leaving the +refrigerator, causing the pipe from the refrigerator to the compressor +to become covered with frost. This is a waste and may cause a high +pressure on the low side. + +[Illustration: FIG. 47.--Arrangement where it is desired to use cold +brine in some machine such as an ice-cream freezer. This is the same +refrigerating system as shown in Figs. 45 and 46.] + +Usually the low pressure side carries 10-20 pounds pressure and the +high side 125-150 pounds. + +If the ammonia passes the expansion valve too fast, as mentioned above, +it may cause the compressor to labor too hard and so cause pounding. +If not enough ammonia is passing the expansion valve, the rate of +refrigeration is reduced. + +The cost of operating a refrigerating machine varies. The principal +items are: 1, Power; 2, water; 3, incidentals (refrigerant oil, and +the like); 4, repairs. No figures can be given for the cost of a ton +of refrigeration because of the variation in the price of each of the +items mentioned. + +Some very compact refrigerating systems are on the market especially +adapted for making ice-cream in places where space is limited. The +principle of operation of these machines is the same as all other +expansion systems. + + +ABSORPTION SYSTEM + +The absorption system is not as common as the compression. When used, +it seems to be very satisfactory. + + +=103. Operation of absorption refrigerating system.=--The following +principles of operation, and Fig. 48 of an absorption refrigerating +machine, are contributed by Henry Vogt Machine Company. + +“The first step is pumping a strong charge of what is technically known +as aqua ammonia, or, in plain terms, a solution of water and anhydrous +ammonia, from the absorber into the bottom pipe of the rectifier. It +is then forced upward through the inner pipes or tubes and out from +the top through a pipe connected to the top of the exchanger where the +strong liquid passes down through the inner pipes or tubes and out at +the bottom through a pipe connecting with the ammonia generator. + +“Within the generator the ammonia gas is driven off from the strong +solution by the heat in the steam coils, leaving a weak solution of +aqua ammonia in the lower part of the generator. + +“The generated gas, under pressure passing out at the top of the +generator, enters the rectifier through the top connection and is +forced downward through the outer pipes. In transit through the +rectifier, the strong aqua absorbing some of the heat in the gas, +condenses whatever moisture is in it. The gas passes out of the bottom +of the rectifier into a separator where baffle plates separate the +moisture from the gas. + +[Illustration: FIG. 48.--Diagram of the Vogt absorption refrigerating +machine, showing pipe connections and directions in which the liquids +and gases travel throughout the entire system.] + +[Illustration: FIG. 49.--General arrangement of double pipe absorption +machine, showing the connections and the direction in which the liquids +and gases flow.] + + 1. H. P. gas; 2. Purge; 3. Water outlet; 4. Purge; 5. H. P. trap; + 6. H. P. gas; 7. Purge; 8. Water; 9. To sewer; 10. Purge; 11. Purge + drum; 12. Equalizing main; 13. Purge; 14. Steam coils; 15. Trays; + 16. Pump-out; 17. Drain; 18. Gauge board; 19. Oil trap; 20. Exhaust + steam; 21. Trap; 22. Weak aqua main; 23. Strong aqua main; 24. Boiler + steam; 25. Aqua ammonia pump; 26. Exhaust; 27. Drain; 28. Pump-out; + 29. Pump-in; 30. Pump-out; 31. Gauge lines, 32. Equalizing main; 33. + S. A. Draw-off; 34. Charging connection; 35. Charging connection; + 36. Drain; 37. Check; 38. L. P. Gas; 39. Ammonia liquid; 40. Weak + aqua; 41. Regulating valve; 42. Water outlet; 43. W. A. Draw-off; 44. + Check; 45. Liquid mains; 46. Accumulator W. A. Draw-off; 44. Check; + 45. Liquid mains; 46. Accumulator; 47. Outlet; 48. Drip; 49. Fresh + water main; 50. Check; 51. Expansion valve. + +[Illustration: FIG. 50.--General arrangement of atmospheric absorption +machine, showing the connections and the direction in which the liquids +and gases flow.] + + 1. Water main; 2. Purge; 3. Purge; 4. H. P. Trap; 5. H. P. Gas; + 6. H. P. Gas; 7. Drip; 8. Check; 9. Strong aqua; 10. Drip; 11. + Pump-out; 12. Weak aqua; 13. Gauge; 14. Trays; 15. Steam coils; 16. + Gauge glass; 17. Boiler steam; 18. Exhaust steam; 19. Grease trap; + 20. Drain; 21. Gauge board; 22. Liquid main; 23. Strong aqua main; + 24. Weak aqua main; 25. Gauge; 26. Trap; 27. Aqua ammonia pump; 28. + Exhaust; 29. Drain; 30. From boiler; 31. Air chamber; 32. Pump-in; + 33. Equalizing main; 34. Charging connection; 35. Pump-out and + blow-in; 36. Drain; 37. Charging connection; 38. Blow-in line; 39. + Gauge line; 40. Liquid main; 41. Accumulator; 42. Expansion valve; + 43. Purge; 44. Purge drum; 45. Water main; 46. Equalizing main; 47. + Gas main; 48. Check; 49. W. A. main; 50. W. A. Draw-off; 51. Strong + Aqua tank; 52. Gauge glass; 53. S. A. Draw-off; 54. Check. + +“The moisture is trapped back to the generator while the dry gas +continues to the condenser, where it enters at the top of the shell +or coils. Being brought into contact with the water cooled surface +of the condenser, the sensible as well as the latent heat of the +ammonia is extracted, and the gas quickly liquifies. This liquid +ammonia is conducted to the brine cooler or refrigerating coils where +it evaporates by absorbing the heat contained in the brine or air +surrounding the coils, thus performing the work of refrigeration. The +vapor or gas thus formed is piped to the bottom of the absorber. + +“The weak aqua ammonia, in the meantime, passes from the bottom of the +generator to the bottom of the exchanger and flows upward through the +outer pipes for the purpose of exchanging the heat with the strong aqua +ammonia flowing downward through the inner pipes. + +“From the top of the exchanger the weak aqua is conducted to the bottom +of the weak aqua cooler, flowing up through the outer pipes to be +further reduced in temperature by cooling water passing down through +the inner pipes. Finally it flows in the top of the absorber where the +ammonia vapor from the refrigerating coils, owing to its great affinity +for water, is rapidly absorbed by the weak aqua, forming again the +strong solution of aqua ammonia. The double cycle of circulation is +thus completed. The same operation is repeated indefinitely.” + + +=104. Arrangement of double pipe and atmospheric absorption +machines.=--There are several types of the absorption machines. The +general arrangement and the direction of the flow of gases and liquids +are shown in Figs. 49 and 50. + + + + +CHAPTER IX + +_PREPARING THE MIX_ + + +Mix is a term applied to the unfrozen ice-cream. It is sometimes called +“batch” or “batter.” The amount of mix prepared at one time may be +enough for one or several freezers or for a whole day’s freezing. + + +=105. Importance of preparing the mix.=--The preparing of the mix is +one of the most important phases of the ice-cream business, because +of the control of flavor, the effect on the body and texture, and +financial considerations. + +If the flavors were always uniform, it would be a simple matter to +prepare the mix. This not being the case, it requires considerable +practice and skill to know exactly how to blend them. The mixer of +the different materials should know which must be rejected and which +used and in what flavors of ice-cream. The sour or acid flavor can be +determined easily in the milk products by means of the acid test. For +its use, see Chapter XIV. Besides this, many other undesirable flavors +are present in the materials. For example, it would be unwise to try to +mix acid fruits with cream already high in acid, since this probably +would cause a pronounced sour taste and might curdle the cream. Some +makers believe that the flavor added to the ice-cream will cover up any +bad flavors in the milk products, but this is not the case. If there +is any undesirable flavor in the materials it can be detected in the +ice-cream. Of course the person preparing the mix has the receipt +or formula but this is only a general guide; the final test is the +taste. Each mix should be tasted before it is frozen to make sure that +the flavor is correct. If not palatable in the mix, it will not be in +the ice-cream. In some cases, it is necessary to have the flavor more +pronounced in the mix than is desired in the finished product because +the flavor may freeze out or become less pronounced. + +From the financial viewpoint, mixing is one of the most important parts +of the whole enterprise. Here the question of whether the business is +to be a success or failure is largely determined by the cost of the +materials. After the materials have been determined, it is necessary +to see that the exact amount is used in each mix. This means that each +mix must be standardized, both for fat and total solids. For method +of standardization, see Chapter XIV. An example may illustrate what a +small loss will amount to in dollars and cost a gallon. Suppose 1000 +pounds of cream testing 20 per cent fat were desired and instead of +this it tested 20.5 per cent fat. This would use 5 pounds more fat +which at $1.00 a pound would equal $5.00; the wages for a good man. +This 1000 pounds of cream would make approximately 250 gallons of +ice-cream. The $5.00 additional cost for 20.5 per cent cream would +make the ice-cream cost 2 cents a gallon more. This shows that a small +divergence in cost a gallon may make a big total difference especially +noticeable if near the dividing line between profit and loss. Another +example indicates how carefully the mix may be standardized to reduce +cost. An ice-cream plant found that the mix could contain .21 per cent +of acidity without injury to the quality of the product. Each material +was tested for acidity (see Chapter XIV), and because there was an +abundant supply of buttermilk for which there was no market, the mix +was standardized to .21 per cent acidity by the use of buttermilk. This +reduced the cost by using a material for which there was no market. +The body and texture are largely determined by the materials employed, +although the freezing and subsequent handling has a decided influence +on the quality. + +Too much study cannot be given to the question of the materials to +be used in the mix nor too much pains taken to see that each mix is +properly standardized. + + +=106. Usual procedure in preparing the mix.=--Much detail variation +in preparing the mix is possible and yet obtain accuracy and good +quality of ice-cream. The usual procedure is as follows: The milk +products are first put into the container in which the mixing is to be +done. In a large ice-cream plant some type of the mechanical mixer, +Figs. 20, 21, 22, 23, and 24, is used. A view of a mixing-room is +shown in Fig. 51. The mixers are just above the level of the floor, +making it easy to put materials into them. In this case, the mixers +are above the freezers so that the mix flows by gravity. Each material +should be weighed or measured accurately. After the materials are +mixed together, it is often desirable to test them to make sure that +the desired standardization has been obtained. The sugar is weighed +next into the mix. The amount will vary according to the flavor and +materials used. For example, with sweetened condensed milk, less sugar +will be required. Time should be allowed before freezing for the sugar +to dissolve. This can be hastened by stirring, which may be done by +a mechanical or hand agitator, depending on the size of the mix. +Whichever method is employed, care should be exercised not to stir the +mix enough to cause the fat to churn. This would cause lumps of fat or +butter in the ice-cream. + +[Illustration: FIG. 51.--Mixing room in large ice-cream plant.] + +The stabilizer is added next. In some cases, such as the prepared +ice-cream powders, it should be mixed with the dry sugar and added with +it. If gelatine or gum tragacanth is used, it should be applied slowly +and the mix agitated to prevent lumps forming. For method of preparing +gelatine, see Chapter IV. If color is desired, it should be put in +just before the flavor. This will prevent streaks in the ice-cream. +Lastly, the flavor should be added, care being taken to use the exact +amount. In the case of fruit ice-cream, the fruit may not be put in +until the mix is partly frozen. If acid fruits are stirred in the mix +before partly freezing, the cream might curdle. If the fruit is added +to the mix and then frozen in an upright freezer, there is danger of it +settling to the bottom. + +If it is desired to emulsify or homogenize the whole mix, this should +be done before the flavoring materials are added. The flavoring might +be lost during the process and pieces of fruit would clog the machine. + +When ready to freeze, the mix should be tasted to make sure that +everything has been added and that the mix has the proper flavor. Of +course little can be told about the body and texture of the resulting +product by tasting the mix. But the flavor is a good index of that of +the ice-cream. + + +=107. Temperature of the mix.=--As will be pointed out in connection +with over-run, the temperature of the mix when it enters the freezer +is very important. If too warm, the cream will churn before it will +beat up or whip. Most of the mechanical mixers possess some means of +controlling the temperature of the mix. But the operator should make +sure that the mix is at the desired temperature. It should never enter +the freezer above 60° F. and the nearer 40° F. the better. + + + + +CHAPTER X + +_FREEZING PROCESS_ + + +The principles of freezing are the same whether a large or small +freezer is employed. It is usually harder to control the process in a +small receptacle. In a large plant the freezers are arranged in a row +or battery, as shown in Fig. 52. One man operates six to eight, with a +helper to carry the ice-cream to the hardening-room. + + +=108. Purpose of freezing.=--Freezing is for the purpose of cooling the +mix and getting it in such condition that it is edible while frozen. +If frozen without agitation it would be icy and grainy. If the mix +is placed in the freezer too warm, it is liable to churn. Freezing +incorporates air into the ice-cream and so gives pore space. The +increase in volume due to freezing is known as “swell” or “over-run.” + + +=109. Rate of freezing.=--If the freezing is not properly done, the +result is a loss in both quality and quantity of ice-cream. The rate or +time required to freeze is affected by different factors, depending on +the type of machine used. + +In the brine freezer, the rate is dependent on the following factors: +1. Temperature of brine; 2. rate of flow of brine; 3. temperature of +materials when put into freezer; 4. materials in mix; 5. speed of the +freezer. + +[Illustration: FIG. 52.--Battery of freezers in a large ice-cream +plant.] + +In the tub and can freezer the rate is dependent on the factors: 1. +Proportion of salt and ice; 2. amount of brine; 3. mixture of salt and +ice and brine; 4. speed of freezer; 5. temperature of materials when +put into freezer; 6. materials in mix. + +Ice-cream should not be frozen too fast or too slowly nor for too long +or short a period. If the extremes occur, the quality and quantity are +affected. + + Results of freezing too rapidly: + 1. Cannot obtain swell. + 2. Causes cream of poor quality. + 1. Soggy or heavy--due to lack of air space. + 2. Grainy in texture. + 3. Does not hold well in storage. + + Results of freezing too slowly: + 1. Cream is liable to churn, causing chunks of butter in the + ice-cream. + 2. Greasy ice-cream. + 3. Cannot obtain swell. + 4. Ice-cream usually lumpy. + + Results of not freezing enough: + 1. Ice-cream is watery. + 2. Ice crystals separate while hardening. + 3. Do not obtain proper swell. + 4. Fat rises to surface of the ice-cream. + + Results of freezing too much or too long: + 1. Liable to churn cream. + 2. Lose swell. + 3. Ice-cream is liable to be greasy. + 4. Ice-cream is soggy and heavy. + +The rate of freezing can be regulated much easier in the brine than in +the tub and can freezer. In the former the condition of the ice-cream +can be seen without stopping the machine, and also the temperature +taken. On the other hand, with the tub and can freezer, the machine +must be stopped each time and the cover removed in order to see the +condition of the ice-cream or to take the temperature of it. With the +brine freezer the rate of flow of the brine can be regulated. The +temperature of the brine alone is not important, but the rate of flow +must be considered. In the tub and can freezer the proportion of ice +and salt can be regulated, but this is not very satisfactory. The +ratio of salt to ice regulates the rate of freezing. (See page 108.) +Usually one part salt to twelve to eighteen parts of ice is the correct +proportion. The finer the ice and salt, the more rapid the freezing. + +The rate of freezing is also affected by the amount of sugar and solids +in the ice-cream. The effect of sugar on the temperature is shown in +Table V. + +TABLE V + +Effect of sugar on freezing + + _Percentage of sugar_ _Temperature of freezing_ + _in solution_ _Degrees F._ + + Skim-milk 31.03 + 5 per cent solution of sugar 30.40 + 10 per cent „ „ „ 29.70 + 14 per cent „ „ „ 28.60 + 25 per cent „ „ „ 27.07 + +The effect of a large percentage of sugar on the freezing is especially +noticeable in the case of sherbets and ices. These freeze much slower +than ice-cream. + + +=110. Proper method of freezing.=--The question might be asked as +to the proper way to freeze ice-cream. Because of the many factors +involved, the only direct answer is to state that the process should +result in a mellow body, smooth texture and medium swell. The colder +the mix when it enters the freezer, down to 40° F., the better the +control. It should take from twelve to twenty minutes to freeze. The +mix should be cooled quickly to 32° F., then the flow of brine partly +shut off and the cream allowed to whip. When the cream is nearly +whipped, the brine should be turned on gradually and the cream allowed +to freeze. When the mix is partly frozen, the fruit should be added, +soon enough so that there will be time for it to become uniformly +distributed in the mix. It is the usual practice to crush the whole +fruits before putting them in the freezer. This can easily be done +by forcing them through a food chopper. The cream should come from +the freezer at a temperature of 26° F.-28° F. The appearance of the +ice-cream and its temperature is a good index when frozen enough. It +should have its peculiar characteristic (dead) not shiny appearance. +When the thermometer is placed in the freezer and drawn out, the +ice-cream should adhere to it and the part remaining on the thermometer +should retain its identity for a few minutes. + +Experiments[26] show that between 29° F. and 26° F., the volume of the +ice-cream increases as the cream whips. The flow of brine, therefore, +should be regulated so that the cream will be at the temperature at +which it will whip, for the maximum of time. If the freezer is run with +the mix too warm, the cream will churn, and if the mix is too cold, the +cream will not whip. + +[26] Washburn, R. M., “Principles and practice of ice cream making,” +Vt. Exp. Sta., Bul. 155, 1910. + +In a tub and can freezer it is difficult to control the factors +regulating the rate of freezing. When the mix begins to thicken and +so turns hard, the speed of the freezer is increased. This beats up +the ice-cream and causes more swell. When the dasher and ice-cream are +removed, the freezing-can will float in the brine, causing considerable +difficulty when the next mix is ready to be frozen, since it will not +easily go back in place. If the freezing-can cannot be centered in the +tub, the cold brine should not be wasted, but should be dipped out and +poured back after the can is in place. This saves considerable ice. In +many plants, no attempt is made to center the can in the brine, this +being dipped out as soon as the ice-cream is removed. + +One of the important factors in freezing is to obtain the proper swell. +So far as this is concerned, the time to draw the ice-cream from the +freezer can be told by the over-run tester. (See Chapter XIV.) + + +=111. “Over-run” or “swell.”=--It should be the aim of the person +freezing the ice-cream to obtain the proper over-run with each freezer. +A large number of factors affect the amount of swell, and the possible +combinations of these must be known. If too much swell is obtained, +the ice-cream will be very porous, light and fluffy, and have a grainy +texture; if not swell enough, it will be very heavy and soggy and may +or may not be grainy in texture. For the best results, a medium swell +is to be desired. The factors affecting swell[27] may be divided into +two general classes: kind and preparation of materials used, manner or +method of freezing. + +[27] Washburn, R. M., “Principles and practice of ice-cream-making,” +Vt. Exp. Sta., Bul. 155, 1910; Baer, A. C., “Ice-cream making,” Wis. +Exp. Sta., Bul. 262, 1916; Mortensen, M., “Factors which influence the +yield and consistency of ice-cream,” Ia. Exp. Sta., Bul. 180, 1918; +Ellenberger, H. B., “Swell in ice cream,” Thesis, Graduate School, +Cornell Univ., 1915. + +I. Kind and preparation of materials used. + + 1. Age, viscosity, acidity, and fat-content of milk and cream. + + 2. Size of fat globules in cream. + + 3. Ageing of mix. + + 4. Pasteurizing of milk and cream. + + 5. Use of homogenizer. + + 6. Use of emulsor. + + 7. Methods of mixing. + + 8. Use of condensed mix. + + 9. Amount of sugar. + + 10. Different kinds of flavoring. + + 11. Fillers and binders. + + 12. Total solids in mix. + +The older the milk and cream and the more acidity they contain, the +more viscous they will be. This is to be desired since it will whip +more readily. For test for viscosity, see Chapter XIV. The more fat +present in the milk and cream the more viscous they will be and the +smaller the fat globules, the more the cream and milk will whip. It +is commonly known that in order to obtain viscosity and swell, aged +cream must be secured. Instead of ageing the milk and cream, some +manufacturers age the whole mix. If only the former are aged and these +should sour, they could be churned into butter. However, if the sugar +and flavoring are added to the mix and the whole aged and in the +process become sour, the cream would not make good butter when churned. +Therefore, there is danger of greater loss when the whole mix is aged. +Pasteurization temporarily destroys the viscosity of the milk and cream +and as a result pasteurized cream must be aged longer to restore the +viscosity. The homogenizer and emulsor breaks the solids of the milk +and cream into smaller particles. In some plants the whole mix is +homogenized or emulsified before going to the freezer. This increases +the viscosity and because of this and of the smaller particles, more +swell is possible without sacrificing quality. With the emulsor, cream +can be made from butter and skim-milk, but it lacks the force of the +homogenizer, and so cannot break up the solids as can the latter. +Emulsified cream is more viscous than raw cream of the same age. + +While mixing, care should be exercised not to churn the cream. If +churning takes place, it reduces the solids and so the possible swell. +By the use of condensed or powdered milk, the amount of total solids in +the mix is increased. Condensed milk usually causes the mix to become +more viscous. The amount of sugar is important only because of its +bulk; the more sugar added, the more solids in the ice-cream. The swell +is affected by the flavoring since some flavors add more bulk. + +Authorities disagree as to the effect of binders and fillers on swell. +If some cause an increased swell, this is very slight. The total solids +in the mix have a decided influence on the amount of swell that can +be obtained without injury to the quality of the ice-cream; the more +solids in the mix, the more swell. + +II. Manner or method of freezing. + + 1. Speed of dasher in freezer. + + 2. Temperature of mix entering the freezer. + + 3. Temperature of brine and rate of flow. + + 4. Temperature of mix while whipping. + + 5. Time of whipping. + + 6. Total time to freeze. + + 7. Temperature of ice-cream when drawn from freezer. + + 8. The amount of mix in the freezer. + +The manufacturers of the different freezers have studied their machines +and determined the speed at which they should run. The ice-cream-maker +should see that the freezer runs at the speed indicated. + +The nearer the temperature of the mix to 40° F. when put into the +freezer, the easier it is to obtain the swell. + +Mortensen[28] says “that a temperature of about 6° F. for the +circulating brine would be the most desirable when using a 20 per cent +raw cream. For pasteurized cream a temperature of from 8 to 10° F. +gave the best results, while for emulsified cream about 10° F. and for +homogenized cream 14° F. proved the most satisfactory.” No record of +the rate of flow of brine is recorded. The temperature and flow of the +brine should be such that the desired swell is obtained together with +the quality. + +[28] Mortensen, M., “Factors which influence the yield and consistency +of ice-cream,” Ia. Exp. Sta., Bul. 180, 1918. + +Washburn[29] shows that the mix whips at certain temperatures, usually +from 32° F. to 29° F. The length of time of whipping has a decided +influence on the quality of the ice-cream and the amount of swell. + +[29] Washburn, R. M., “The principles and practice of ice-cream-making,” +Vt. Exp. Sta., Bul. 155, 1910. + +The total time to freeze has a noticeable effect on the quality of the +ice-cream and the amount of swell. If frozen too quickly, swell will +not be obtained and if too long, swell will be lost. + +Washburn[30] proves that the temperature at which the ice-cream is +drawn from the freezer has a marked effect on the swell. If frozen too +cold, the swell is lost. + +[30] Washburn, R. M., “The principles and practice of ice-cream-making,” +Vt. Exp. Sta., Bul. 155, 1910. + +According to Mortensen[31] the amount of mix in the freezer influences +the swell. For the best results, the freezer should be about half full. + +[31] Mortensen, M., “Factors which influence the yield and consistency +of ice-cream,” Ia. Exp. Sta., Bul. 180, 1918. + +Certain combinations of the factors mentioned above will increase the +swell, while certain ones will decrease it. + +To obtain swell: + + 1. Have viscous milk and cream. + + 2. Age the milk and cream or mix. + + 3. If pasteurized milk and cream are used, they should be aged until + viscous. + + 4. The cream and milk or whole mix should be homogenized or + emulsified. + + 5. Condensed milk in the mix would aid in obtaining swell. + + 6. The mix should contain at least 30 per cent of total solids. + + 7. The dasher should run at the required speed. + + 8. Mix should enter freezer as near 40° F. as possible. + + 9. There should be a supply of cold brine, from 6° F. to 10° F. + + 10. The cream should be whipped for a moderate time in the freezer. + + 11. The mix should fill the freezer half full. + + 12. It should require 12-20 minutes to freeze. + + 13. The ice-cream should not be below 27° F. when drawn from the + freezer. + +The converse of these conditions will cause a decrease in the amount of +swell. + + +=112. Condition of ice-cream when removed from freezer.=--When taken +from the freezer, the ice-cream is in a semi-solid condition. It +is soft enough to flow from one container to another and yet hard +enough to retain the incorporated air. In order to use the freezer +over and over, the ice-cream is usually placed in pack-cans to harden. +A parchment paper is put over the top of the can before going to +hardening-room. The ice-cream can be drawn from brine freezers directly +into the pack-cans. With the tub and can ice freezers, it is necessary +to dip the ice-cream from the freezer into the pack-cans. This is more +easily done if the dasher is first removed. + + +=113. Freezing sherbets and ices.=--The foregoing statements apply +to ice-cream and may or may not be applicable to sherbets and ices. +Because of the higher percentage of sugar and water, the latter usually +freeze more slowly. Any difference in procedure is noted under the +receipt for sherbets and ices. + + + + +CHAPTER XI + +_HARDENING ICE-CREAM_ + + +Ice-cream which is of good quality up to this stage in the +manufacturing process may be spoiled or the quality impaired by +improper hardening. The object, as its name indicates, is to harden +the semi-frozen product after it is frozen in the freezer. During the +time that the ice-cream is hardening, the flavors of the different +ingredients blend to give the desired characteristic flavor. + + +=114. Methods of hardening.=--The ice-cream may be hardened in the +freezer, but this allows only one mix to be frozen and the machine +cannot be used again until the product is consumed. This method is +ordinarily followed with the small hand freezers. With the larger +freezers, however, the ice-cream is hardened in pack-cans (Fig. 25) +or bricks. (Fig. 58.) This allows the freezer to be used over and +over. The ice-cream can be drawn directly from the brine freezer into +the pack-cans or bricks; however, with the salt and ice freezer, the +ice-cream must be dipped by hand. Various ladles or scoops have been +devised for this purpose. (Fig. 53.) These are more or less rounded on +the edge to scrape the sides of the freezing-can. + +The ice-cream in the pack-cans or bricks may be hardened in any one +of several ways: packing in an ice and salt mixture, setting in cold +brine, setting in a cold room called a hardening-room. The first two +are not advisable for a large ice-cream plant because of the work and +space required. + +[Illustration: FIG. 53.--Different styles of transfer ladles or scoops.] + + +=115. Hardening in ice and salt mixture.=--When the ice-cream is +hardened in a salt and ice mixture, the cans are placed usually in a +large plank box, Fig. 54, so that there will be a space of four to +six inches between the cans and the box. The size of the box will be +determined by the amount of ice-cream manufactured. If five-gallon +cans are used, it is advisable to build the box in compartments which +will hold six. This will require a box 26 inches wide by 32 deep by 36 +long, outside measurement, with a hinged cover for each compartment. +The box should be made of two-inch matched lumber so that it will not +leak. There should be a hole in the side near the bottom so the brine +can be drawn off. Before beginning to freeze, it is advisable partly +to pack the cans in the box. A layer of four to six inches of cracked +ice should be placed in the bottom of the box, then the cans placed +in position and the box filled about two-thirds the height of the can +with cracked ice. Some salt should be sprinkled on the ice and the box +filled to the top of the cans with cracked ice. This cools the cans +so that there will be no melting when the ice-cream is put in. The +ice-cream may be poured directly from the freezer into the pack-cans +or first it may be put into some container which is easier to handle +and then poured from it into the pack-can. When all the cans in the +compartment are full, they should be covered to a depth of four to +six inches with ice and salt. These may be mixed before putting in the +box or they may be placed in alternate layers. The proportion of salt +to ice for hardening is about one part of salt to eighteen or twenty +parts of ice by weight. Most of the salt should be placed in the upper +third of the ice, because as the ice melts the salt goes into solution +and so is carried to the bottom of the box where it comes into contact +with ice where there is little or no salt. For packing, a coarse +salt is to be preferred as it dissolves more slowly. After standing +overnight in the pack-cans, the ice-cream should be hard. It may be +shipped out or held until wanted. If shipped the cans may be packed in +tubs, observing the same precaution of placing the salt in the upper +third of ice. Instead of packing in a tub, the cans may be put in a box +or cabinet on the delivery wagon. If the ice-cream is to be held in +the hardening-box, it should be repacked twice a day. This is done by +jamming down the ice and salt. The cans should then be recovered with +ice and salt. The brine which forms should be allowed to escape from +time to time so that it will not run into the cans or cause them to +float. The following figures on the amount of ice and salt used were +obtained by the “Ice-Cream Trade Journal.”[32] They are the average of +a number of plants: + +[32] “Ice-Cream Trade Journal,” Vol. V, No. 6. + + Average output of ice-cream per day, summer 395 gallons + Average output of ice-cream per day, winter 43 „ + + Amount of ice used per 100 gallons of ice-cream 1928 pounds + for freezing 614 „ + for hardening and storage 914 „ + for shipping delivery or cabinets 400 „ + + Amount of salt used per 100 gallons of ice-cream 190 „ + for freezing 73 „ + for hardening and storage 82 „ + for shipping delivery or cabinets 35 „ + +[Illustration: FIG. 54.--Plank box for hardening ice-cream in a salt +and ice mixture. The cans are placed in perforated cylinders so that +they may be changed and the ice will not fall in and fill the space.] + + +=116. The slush-box or brine-box method of hardening.=--In this method, +the pack-cans instead of being packed in ice and salt are placed in +a box or tank of brine. This brine is usually cooled by means of a +mechanical refrigerating system, and circulated with a pump. Great care +must be exercised or the brine will get into the ice-cream. + + +=117. The hardening-room.=--In the large ice-cream plants, a cold room +is maintained in which the pack-cans are set to harden. This room is +cooled by mechanical refrigeration and the temperature should be very +near 0° F. or below. There are three general types of hardening-rooms, +depending on the location of the evaporating coils and the air +circulation. + + +=118. The still-air type.=--This type of hardening-room is used in the +smaller ice-cream plants. The evaporating coils are placed directly in +the hardening-room and usually arranged in such a way that shelves are +formed with parts of the coils on which the cans of ice-cream are put +to harden. (Fig. 55). + + +=119. The gravity-air type.=--In this system the coils are placed in a +bunker-room directly over the hardening-room and designed so the air +will circulate in a natural manner. + +[Illustration: FIG. 55.--Still-air hardening-room showing evaporating +coils forming shelves on which the pack-cans of ice-cream are placed to +harden. Other evaporating coils may be seen on the sides and ceiling.] + + +=120. The forced-air type.=--This system locates the coils in a +bunker-room usually, directly over the hardening-room, and the air +is forced to circulate by means of a fan or blower. (Fig. 56). The +forced-air system is considered the most efficient. The effect is +the same as the temperature of the air on the body. With the same +temperature, the cold is more noticeable and more penetrating on a +windy day than when the air is still. The same is true in the hardening +of the ice-cream. The objection to the still-air hardening-room is the +longer time required to harden the product. The objection to the +forced-air room is the danger of losing too much refrigeration when the +doors are opened unless the fan causing the air circulation is stopped +before opening. + + +=121. Defrosting the coils.=[33]--“One of the most troublesome things +to be contended with in ice-cream hardening-rooms, cooled by means of +refrigerating machines, is the accumulation of frost or snow on the +coils, and up to the present time no thoroughly satisfactory method has +been devised which will meet with success under all conditions, taking +into consideration, method of operation, design of coils, and the like. + +[33] Carpenter, M. R., “Defrosting of coils in hardening-rooms.” +“Ice-Cream Trade Journal,” Vol. XI, No. 4. + +“The most serious objection to this accumulation is the loss in +efficiency, which may amount to as much as 50 or 75 per cent, depending +on the thickness of the coating and the interference with the air +circulation. The other objections are of minor importance and need not +be considered here.” + +1. _Cooper system._ + +The Cooper system consists of a trough perforated at the bottom and +placed directly over each stack of coils, and in which are put lumps of +chloride of calcium. This substance, on coming in contact with moisture +in the air, will dissolve slowly and drip down over the coils, thereby +keeping them practically free of frost at all times. It may be asserted +that this is not a defrosting device; however, prevention is better +than cure. + +This system can be applied to the first and second types of rooms, +as in these cases the floor under the coils is made water-tight and +arranged to catch the drip from the coils. It is not suitable for +use in the third type, however, as the drippings would fall upon the +cream-cans and on the floor of the room. It is possible to catch these +drippings and by boiling or evaporation recover the calcium, which can +be used over again or in strengthening the brine in the tanks. + +[Illustration: FIG. 56.--Forced-air hardening-room.] + +The objection to this system is the labor involved in placing it in the +troughs, for usually the coils are close together and are in a room +with little space around and over them for a man to work; also, the +rooms being cold, it is a very uncomfortable task. It may be possible, +in designing rooms, to provide space in which to work, or to fill the +cans outside the room and then place in position. + +2. _Cold brine drip system._ + +This system consists of a means of spraying cold brine (calcium or +salt) over the coils. Over each stack of coils is placed a trough, +slotted or perforated pipe, similar to the water pipe or trough on +atmospheric condensers. Brine from the main tank or circulating system +is turned into the trough and allowed to drip over the coils either +continuously or intermittently as may be required. + +In this system the brine must be very strong or it will freeze on the +lower coils, especially if the frost is allowed to accumulate to any +extent before defrosting, or unless the coils are out of commission +entirely during the operation. This brine is sometimes allowed to drain +directly back into the brine tank, although this is poor policy as it +weakens the brine and has a tendency to make it (in the case of calcium +brine) acid, owing to its contact with the air. A better way, if it is +possible to do so, is to drain it back into a tank, where it can be +boiled and thus brought to its proper strength before returning to the +main tank. This system has the advantage of being operated with little +labor and under comfortable conditions, providing the controlling +valves are placed outside the room and of easy access. In case the +frost is allowed to accumulate to any extent, this system will not work +as quickly as may be desired. One great advantage, however, is that it +will not warm up the hardening-room, and if operated often and properly +it will keep the coils free of frost and not require the room to be +out of commission. This system is suitable for use in first and second +types of rooms. + +3. _Hot brine system._ + +This is arranged the same way as the cold brine drip system as far as +interior arrangement on coils is concerned, but instead of using brine +from the main tank, a special tank with steam coil is provided and +the brine is pumped into the trough in a hot condition and allowed to +drain directly back into the tank. This system is quick in its results. +A heavy deposit of frost can be removed in this way and it is easily +operated. + +The principal objection is the great amount of moisture it will cause +to be deposited on the walls and ceiling of the room. It also requires +the room to be out of commission a short time while being operated. +However, it does not seem to have much effect on the temperature after +it is shut off. + +This method can also be made a cold brine system by boiling off after +using, then letting it stand until it is cold before utilizing again. +However, it will still deposit some moisture and it has been found best +to keep the room out of commission while operating. Another tank with +refrigerating coil placed so as to cool this brine before using might +be beneficial, although in this case it resolves itself into system No. +1. This can be applied to first and second types. + +4. _Air blast system._ + +In this system the air is so designed that the bunker-room can be +shut off from the hardening-room and openings arranged so that the +circulation fan can draw warm air from outside, blow it across the +coils and discharge it at the opposite end. This is a very satisfactory +and quick method, although it leaves some moisture deposited on the +walls of the room and has a tendency to warm things up a little. This +system, of course, needs a fan and is suitable for the first type only. + +5. _Hot gas system._ + +This is a radical change from those systems considered, as it works +from the inside out. The success of this system depends on the design +of the coils, headers and connections. The coils are arranged in such a +way that they are, by opening and closing a few valves, converted into +an ammonia condenser with the hot ammonia gas from the discharge of the +compressor entering the top pipe of coils, and, as it is liquefied, +running by gravity back to the ammonia receiver. In operating, it is +necessary to have the room out of commission unless the coils can be +arranged in independent batteries. + +This system can be applied to any type of room provided the coils are +properly designed and the receiver on a level below the lowest coil. +Also, there must be enough additional refrigeration to enable the +compressor to continue in operation in order to supply the hot gas. + +6. _Warm liquid system_. + +The coils, headers and piping are so arranged that the liquid ammonia +on its way to other rooms can be passed through coils which are to be +defrosted. It is self-evident that it is necessary to maintain the same +pressure on these coils as obtains in the main liquid line, also that +a considerable amount of ammonia must be expanding at other points in +order to keep a quantity of liquid flowing through the coils. + +When conditions are right, this system is very satisfactory, as it can +be operated with a minimum of labor and has the advantage of conserving +all the energy previously expended in freezing the ice on the coils. In +applying, special consideration must be given to the method by which +the ammonia is fed into the coils. It is more easily applied to the +flooded system, as in this case it is only necessary when defrosting +is completed to cut off the flow of hot liquid, open the suction line +from coils and allow the liquid remaining in the coils to expand or +evaporate to accumulator, without danger of flooding over into the +compressor. After this liquid is partly evaporated, the valve on the +feed line from accumulator is opened, and the coils are again in full +operating condition. + +In applying this system to direct expansion coils, care must be +exercised to provide means either to drain the liquid back into the +ammonia receiver before opening the outlet from coils into the main +suction line, or to expand this liquid through other coils; otherwise, +the liquid is liable to reach the compressor with disastrous results. + +The application of this system should be attempted only by those +thoroughly competent to consider all phases of the situation and if +properly applied is one of the most efficient and satisfactory methods +of defrosting yet devised. It can be applied to practically any type of +room providing, as stated, the other conditions are suitable. + +It has been the writer’s experience that the coils in forced-air +circulating types give the most trouble, due to the heavy frost, partly +from the very rapid accumulation and partly for the reason that these +coils being out of sight are more likely to be neglected, and after the +ice has become very heavy it is exceedingly difficult to get it all +off, without keeping the room out of use for a long time. + +The gravity system also gives some trouble, but is not affected quite +so quickly as the forced-air type, owing partly to the design of the +coils which necessitates greater space between pipes. The still-air +type causes very little difficulty and some of these have been run +a whole season without being defrosted and without having their +efficiency materially reduced. + +A large percentage of hardening-rooms have no arrangements for +defrosting and as a result it is often necessary to shut down and +remove the ice. All kinds of methods are used, such as scraping by +hand, spraying with water by means of a hose, placing salamanders in +the room or simply leaving the doors open and allowing the temperature +of the room to rise to such a point that the frost will melt. + + +=122. Time required for hardening.=--The time necessary for hardening +varies, but usually twelve hours is sufficient. The time depends on +the rate of removal of heat or the amount of cold supplied and the +insulation. The refrigerating boxes should be well insulated. This +is especially necessary because of the great difference between +the temperature of the hardening-room and that of the surrounding +atmosphere. Undoubtedly cork makes the best insulation. The thickness +varies, but it should be at least six or eight inches thick. Cork +should be kept dry or it is not a good insulator. When the ice-cream +becomes hard, it should be held at a low enough temperature so that it +will not soften or melt. After hardening, if the ice-cream melts or +softens it is liable to cause the separation of the ice crystals and +so result in a grainy textured product. If it becomes soft, the fat is +likely to rise unless the cream has been homogenized. Ice-cream should +not be held in the hardening-room for more than seven days. + +When an ice and salt mixture is employed to harden the ice-cream, the +rate of hardening is determined by the amount of salt used. The coarse, +slow dissolving salt is to be preferred for hardening. + + +=123. Effect of hardening on quality.=--The two qualities of ice-cream +affected by hardening are the flavor and body and texture. While +hardening, the flavors of the different materials used blend to give +the desired characteristic flavor. Some flavors, especially vanilla, +will freeze out while hardening. The body and texture are affected +only through neglect. If the pack-cans are allowed to stand after they +are filled, before being placed in the hardening-room, some of the +ice-cream next to the sides and bottom will melt, causing a grainy or +icy texture. The same may occur if there is water in the bottom of the +pack-cans when the ice-cream is put in. + +[Illustration: FIG. 57.--Brick ice-cream trowels. Straight and bent +handles.] + +[Illustration: FIG. 58.--Quart and sectional brick molds. The sectional +bricks hold several quarts.] + + +=124. Fancy molded ice-cream.=--There are two kinds of fancy molded +ice-cream, bricks and molds to represent various objects. The ice-cream +is the same with the exception of the form in which it is hardened. +Sometimes a little more stabilizer is used to make the cream more firm. +The brick offers many possible combinations. Each kind of ice-cream +is put into the brick in a layer. Each layer is leveled with a brick +trowel. This trowel is square on the end and just the width of the +brick. (Fig. 57.) A different flavor and color of ice-cream forms each +layer. In some cases the center is a sherbet or pudding. Mortensen +suggests a center layer of solid frozen fruit and calls such ice-cream +Aufait. The size of the brick varies from a pint to several quarts. +(Fig. 58.) It is the customary practice to use sectional bricks (Fig. +58) which are the exact size to hold six to eight quart bricks. These +may have a single or double lid. When hard, the ice-cream is taken +from the sectional brick and cut into either quart or pint sizes. +In a large factory, a special hardening-room is employed for brick +ice-cream, which is kept as near 0° F. as possible. (Fig. 59.) The +contents are taken from the brick mold by applying cold water until +sufficient frost has been drawn from the mold to allow the ice-cream to +slide out. When a large number is made, a special brick-cutting machine +may be used. This will cut the bricks much faster and more uniform in +size than by hand. Sometimes if a knife is run around the sides of the +brick it will help loosen the ice-cream. Care should be taken not to +melt the ice-cream too much. In some instances the bricks are packed in +square, instead of round pack-cans for delivery. In this case a large +number of bricks would be delivered to the same place. The bricks are +wrapped in parchment paper, put into paper cartons and packed in ice +and salt for delivery. + +[Illustration: FIG. 59.--Brick hardening-room.] + +By means of a specially devised mold or brick known as a center mold +(Fig. 60), any letter, figure or form of object may be made in the +center of the ice-cream. To accomplish this, two different colored +ice-creams must be used. The form is produced by having one cover of +the mold with a tube of the desired shape to form the center figure. +The space around the tube is filled with one colored ice-cream and the +tube or center with the color desired in the center. When the brick is +sliced, this design is in the center of each piece of ice-cream. + +[Illustration: FIG. 60.--Center mold and examples.] + +[Illustration: FIG. 61.--Individual ice-cream molds and ice cave for +packing molds.] + +By means of special molds, ice-cream may be hardened to represent +almost any object. (Fig. 61.) These molds are hinged pewter metal. They +vary in size from one or two quarts to an individual service. These +cannot be packed in an ordinary pack-can without jamming. They usually +are wrapped separately with waxed paper and hardened and delivered +in an ice cave (Fig. 61), which consists either of a round or square +pack-can into which a frame with shelves fits. The molds of ice-cream +are placed on these shelves. + + + + +CHAPTER XII + +_JUDGING AND DEFECTS OF ICE-CREAM_ + + +The judging of ice-cream is the comparing of one product with another +or of the one in question with the ideal. In order to make this +comparison more simple, a score-card has been devised. This gives a +numerical value to each of the characteristics of the material to be +judged and makes comparisons easy. The judge should be familiar with +the various qualities and defects of the material under his inspection. + + +=125. Score-cards.=--Several score-cards[34] have been suggested for +ice-cream, but no one is in universal use as is the case with both +butter and cheese. + +[34] Baer, A. C., “Ice-cream-making,” Wis. Exp. Sta., Bul. 262, 1916; +Mortensen, M., “Classification of ice-creams and related frozen +products,” Ia. Exp. Sta., Bul. 123, 1911; Washburn, R. M., “Principles +and practice of ice-cream-making,” Vt. Exp. Sta., Bul. 155, 1910; +Frandsen, J. H., and Markham, E. A., “The manufacture of ice-cream and +ices,” Orange Judd Company, 1915. + +In the New York State College of Agriculture at Cornell University, two +score-cards are used. They are as follows: + + _Score-card No. 1_ _Score-card No. 2_ + Flavor 45 Flavor 40 + Body and texture 35 Body and texture 25 + Richness 10 Bacterial count 15 + Appearance 5 Richness 10 + Package 5 Appearance 5 + Package 5 + ------------------------- ------------------------ + Total 100 Total 100 + +These score-cards consider the same characteristics except that No. +2 includes the bacterial count. Naturally the inclusion of another +characteristic changes the numerical value of the others. Score-card +No. 1 is for use only when there is not time to make a bacterial count, +such as for laboratory work. When an exact comparison is desired, +the bacterial count should be made. If undesirable or large numbers +of organisms are present, they affect usually the flavor and body +and texture, although this is not always true. For this reason, the +numerical value given to bacterial count has been taken from flavor and +body and texture. + + +=126. Explanation of characteristics mentioned in score-card.=--If the +ice-cream is to receive a perfect score, the characteristics should be +as defined. If not, the ice-cream is defective and the score should be +cut. + +_Flavor._--The ice-cream should have a pronounced flavor which will +blend with that of the cream to give a clean, desirable typical flavor. + +_Body and texture._--The body should be firm and mellow. It should +not be tough or rubbery, neither soft or mushy. The texture should be +smooth and velvety and entirely free from graininess and lumpiness. + +_Richness._--If the ice-cream meets the legal requirements, it should +be given a perfect score. If it falls below, it should be scored zero. + +_Appearance._--The ice-cream should have an attractive appearance and +be of the characteristic uniform color. + +_Package._--The package should be neat and clean and, if for long +shipment, some provision should be made to protect the ice on top of +the packing-tub. + +_Bacterial count._--An ice-cream which has a count of 20,000 should be +considered perfect. For each increase of 20,000 above this, one point +should be deducted from the score. + +If a number of samples is to be scored, it is the usual custom to +examine several to gain an idea of how the quality runs. This is called +establishing a key or standard. When this has been done, all the +samples can be scored and the best will not be rated too high nor the +poorest too low. + + +=127. Defects in ice-cream.=--It is almost impossible to make an +ice-cream which does not have some defect. These can be discussed best +under the characteristics as given in the score-card. + + +=128. Defects in flavor= of ice-cream are largely due to objectionable +flavors in the materials employed, or to the use of too much or too +little of certain ingredients. + +Some of the common causes are: + + 1. Use of cream of bad flavor. + + 2. Use of cheap flavoring extracts. + + 3. Use of too little or too much sugar. + + 4. Use of materials which do not give the characteristic flavor. + + 5. Disagreeable flavor due to use of poor fruits. + + 6. Lack of flavor due to use of too small an amount of flavoring + materials. + + 7. Too pronounced a flavor or not pronounced enough. + + 8. Condensed milk flavor. + + 9. Salty ice-cream. + + 10. Gelatine or gum tragacanth flavor. + +Of the ten causes mentioned all but number one are within the control +of the ice-cream manufacturer. However, the flavor of the cream is a +very vital question and the one usually causing the greatest difficulty. + + +=129. Defects in body and texture.=--The texture refers to the +molecular structure. As the ice-cream is an emulsion of materials +of varying specific gravities, it is difficult always to get these +different ingredients to mix in the same manner. The greatest defect in +the texture of the ice-cream is graininess. This may be caused by the +incorporation of too much air or the separation of the water crystals. +After the ice-cream has been transferred from the freezer to the +pack-cans, the latter should be placed at once in cold surroundings; +if not, the cream around the outside and bottom of the can will melt +and on being hardened will be grainy, due to the melting and separation +of the water crystals. Graininess may be due to a lack of binder or +sometimes to the crystallization of the sugar in the condensed milk. + +The body of the ice-cream refers to the structure as a whole. The +common defects in body are hard, brittle, soft or watery. In order to +obtain an ideal body, the ice-cream must contain a certain amount of +milk-fat and other solids; also this cream must be frozen properly. +If the ice-cream lacks solids, the body is very likely to be soft or +watery. The age of the cream, whether or not it has been pasteurized, +and method of freezing, have a decided effect on the body. + +Sometimes in freezing the fat becomes churned; this results in chunks +of fat in the ice-cream. It is caused by the freezer running too fast +or by putting the cream into the freezer too warm. + +The following summary of two bulletins gives the effect of solids on +the smoothness and keeping qualities of ice-cream and the effect of +binders on the melting and hardness. These directly affect the body and +texture. + +Effect of solids on smoothness and keeping quality of ice-cream:[35] + +[35] Brainard, W. K., “Smoothness and keeping qualities in ice-cream as +affected by solids,” Va. Exp. Sta., Tech. Bul. 7, 1915. + +“1. Smoothness and keeping quality or stability of texture of ice-cream +are closely associated. + +“2. Smoothness depends upon the amount and fineness of division of +solids present other than those in true solution, within limits, that +is, the smoothness depends upon the size and distribution of ice +crystals which in turn depend upon the number and nearness together of +minute solid particles which interfere with crystallization and reduce +the size of the ice crystal. + +“3. Colloidal solutions of solids other than fat are best adapted to +ice-cream-making. The finer the division the better. + +“4. The finer the emulsion of the fats the better the homogenizer has +its application in this respect. + +“5. The keeping qualities of ice cream depend upon the stability of +the mix. That is, the keeping qualities of ice cream made from a given +mixture will depend upon the disposition of the solids in that mixture +to separate from the liquid, which in turn depends upon the fineness +of division of the solids. The finer the division, the better the +keeping qualities up to the point at which the solid merges into a true +solution.” + +Effect of binders on the melting and hardness of ice-cream:[36] + +[36] Holdaway, C. W., and R. R. Reynolds, “Effect of binders upon the +melting and hardness of ice-cream,” Va. Exp. Sta., Bul. 211, 1916. + +“_Plain ice-cream._--In plain ice-cream (control) as the per cent of +fat increases the cream becomes softer. A medium amount of butter fat, +combined with other material than milk solids, produces a stiff cream. +When too much fat is present whipping takes place, producing a cream +that is soft and fluffy in appearance. Ice-cream made from eight per +cent cream is no harder than from nineteen per cent cream, while thirty +per cent plain cream is much softer than eight per cent or nineteen +per cent cream. In plain ice-cream the presence of fat increases the +power to resist melting. This resistance is most noticeable between the +melting of the eight per cent and nineteen per cent cream. Thirty per +cent cream shows the power to resist melting to a less degree. + +“_Cream containing gelatine._--Gelatine in a large or small quantity +produces similar effects, depending upon the richness of the cream +used. The power to withstand pressure and the melting resistance +increases as the amount of gelatine increases, when compared with the +control ice-cream with a similar fat content. The hardest and most heat +resisting ice-cream is produced with a medium per cent of fat and a +large amount of gelatine. With gelatine, the presence of fat seems to +be essential to produce hardness and melting resistance until a point +is reached where whipping affects the texture. After whipping begins +the incorporated air reduces the hardness and melting resistance. +Ice-cream containing one ounce of gelatine per gallon has more the +appearance of pudding than ice-cream. Four ounces of gelatine gives +about the same hardness as four ounces of cornstarch, but it is much +better, producing a smoother cream which is more stable under ordinary +conditions. + +“_Cream containing gum tragacanth._--Gum tragacanth with a low per cent +of fat produces an ice-cream that is slightly harder, with slightly +more power to resist heat than plain ice-cream. As the per cent of fat +is increased with this filler, the power to resist pressure and heat +decreases, falling below plain cream, showing that gum tragacanth acts +as a filler and not as a binder. Its most noticeable effects are on +the texture of the ice-cream, because of the nature of the gum, is to +impart a smoothness which becomes sliminess when large quantities are +used. + +“_Cream containing cornstarch._--When cornstarch is used as a filler a +slight increase in hardness and melting resistance is noticeable with +nineteen per cent when compared with eight per cent ice-cream. Also +it produces an ice-cream that has more resistance to heat than plain +ice-cream of the same per cent fat. When used as a filler it compares +favorably with a similar amount of gelatine but the starch ice-cream is +more granular than the gelatine, while gum tragacanth produces a smooth +soft cream.” + + +=130. Defects in richness.=--The only defect in richness is a lack of +fat and solids not fat. The ice-cream should meet the legal standards; +if not it is defective. + + +=131. Defects in appearance.=--Many times the ice-cream does not have +an attractive appearance. It may be rough, grainy and coarse, or partly +melted. Often it will melt on the outside and run while the inside +will be very hard. The ideal ice-cream is one which will have the same +degree of softness throughout. The color is not always characteristic +as the fruit may not be distributed uniformly. + + +=132. Defects in package.=--Anything which detracts from the neatness +of the package is a defect. Badly dented or rusted cans are not +attractive. The tubs may not be clean or neatly painted or lettered. +The parchment paper circles being omitted from the top of the can +constitutes a defect. + + + + +CHAPTER XIII + +_BACTERIA IN RELATION TO ICE-CREAM_ + + +Much might be written regarding the factors affecting the growth of +bacteria, the preparation of the media, the incubating temperature, +the counting; this is all discussed in the various text-books on +bacteriology. Here only the relation of bacteria to ice-cream will be +considered. + +It is commonly recognized that ice-cream contains large numbers of +bacteria. The table No. VI[37] on page 171 shows the average bacterial +count of ice-cream and the highest and lowest counts in various cities +and at different times in the same city. + +[37] Hammar, B. W., “Bacteria and ice cream,” Ia. Exp. Sta., Bul. 134, +1912. + +This table indicates that ice-cream made in different sections of +the United States has some extremely high counts and the average is +comparatively high when one considers the count of milk and cream +produced under clean conditions. The redeeming feature is that +ice-cream can be produced with low bacterial count. This shows the need +of a bacterial as well as chemical standard. + + +=133. Sources of bacteria in ice-cream.=--There are two sources of +bacteria in ice-cream, the materials employed and the utensils which +come in contact with the ice-cream. The latter source is entirely +under the control of the manufacturer. If materials used have a low +bacterial count, there is no reason why the ice-cream should not be low +in bacteria. If this is the case and the ice-cream has a high count, it +would indicate that the maker was careless and the utensils dirty. + +TABLE VI + +Summary of Bacterial Investigations of Ice-cream + + _Average + _No. bacterial + _Source of _Date of samples_ count + ice-cream_ investigation_ examined_ per c. c._ + Philadelphia 1905-06 49 17,833,031 + Boston 1906-07 35 23,000,000 + Washington 1906-07 263 26,612,371 + Chicago 1909 89 16,662,134 + Chicago 1910 386 15,401,000 + Chicago 1911 1,800,000 + Milwaukee 26 + Des Moines 1911 10 19,920,000 + I. S. C. Cream 1911-12 12 19,775,000 + + _Source of _Highest _Lowest + ice-cream_ count_ count_ + Philadelphia 79,000,000 70,000 + Boston 150,000,000 1,000,000 + Washington 365,000,000 137,500 + Chicago 125,000,000 20,000 + Chicago 100,000,000 20,000 + Chicago 200,000,000 90,000 + Milwaukee 8,000,000,000 200,000 + Des Moines 39,000,000 4,200,000 + I. S. C. Cream 72,000,000 500,000 + +Ellenberger[38] found the minimum and maximum number of bacteria in the +materials used in the mix as given in Table VII: + +[38] Ellenberger, H. B., “A study of the bacterial growth in +ice-cream,” Thesis, Cornell Univ., 1917. + +TABLE VII + +The Minimum and Maximum Bacterial Content of the Ingredients used in +the Mix + + _Minimum_ _Maximum_ + Standard cream per c. c. 1,150 37,600,000 + Condensed milk per c. c. 31,500 59,800,000 + Sugar per gram 20 255 + Gelatine 48 891 + Flavoring vanilla 10 321 + +The important fact brought out by the above table is that the milk +products are the source of most of the bacteria in the ice-cream. This +emphasizes the need of dairy products manufactured and marketed under +the most cleanly conditions. The ice-cream-maker in most cases has +little control over these factors. For the production and handling of +milk, see Chapter II. The numbers of bacteria may be reduced materially +by pasteurization.[39] This destroys the viscosity so that milk or +cream that has been aged and then pasteurized must be aged again to +regain it. There is great danger while ageing either pasteurized or raw +cream of a material increase in the numbers of bacteria. Great pains +must be taken to cool and hold or age it at a low enough temperature +so that the organisms will not develop. If this is not done, the result +would be practically the same as if it had not been pasteurized, so far +as numbers of organisms are concerned. + +[39] Ellenberger, H. B., “A study of the bacterial growth in +ice-cream,” Thesis, Cornell Univ., 1917; Hammar, B. W., “Bacteria and +ice-cream,” Ia. Exp. Sta., Bul. 134, 1912; Hammar, B. W., and Goss, E. +F., “Bacteria and ice-cream,” Part II, Ia. Exp. Sta., Bul. 174, 1917. + +Hammar gives the count of different samples of gelatine as follows: + +TABLE VIII + + Bacterial Count of Samples of Gelatine + + _Bacteria in 1 c. c._ + _Bacteria per_ _of ice-cream due_ + _Sample No._ _gram_ _to gelatine_ + 1 113,000,000 565,000 + 2 14,000,000 70,000 + 3 35 0.2 + 4 4,200 21 + 5 85,000 425 + +This table shows the need of testing to make sure that the supply of +gelatine is low in number of bacteria. Usually in the better or more +expensive grades, the bacterial content is lower, but this is not +necessarily true. The method of preparation has much influence on the +bacterial content of ice-cream. (See Chapter IV.) + +Sugar contains very few organisms. The greatest danger is that dirt may +get into the sugar due either to exposure or sifting through the cloth +sacks. + +The flavoring materials may have a decided influence on the bacterial +content of the ice-cream. Vanilla contains very few organisms, but such +flavors as fruits may have large numbers of bacteria, especially if +they are not sound. + +Hammar[40] reaches the following conclusions regarding the bacterial +content of the materials used in the manufacture of the ice-cream: + +[40] Hammar, B. W., “Bacteria and ice-cream,” Ia. Exp. Sta., Bul. 134, +1912. + +1. The cream unless pasteurized is the greatest source of the bacteria +in ice-cream. + +2. After pasteurization cream can be stored at 0° C. for several days +with no important increase in the number of bacteria developing at 37° +C. on agar. + +3. The bacterial content of gelatine is very valuable and some probably +add large numbers of bacteria to ice-cream in which they are used. + +4. The vanilla extract plays a very small part in detaining the +bacterial content of ice-cream. + +5. The sugar is comparatively unimportant as regards the number of +bacteria in the ice-cream made with it, if it has been properly +protected from dirt. + +All the utensils, unless clean, may be a source of contamination to the +ice-cream. When machines are selected, the ease of cleaning should not +be overlooked. All seams should be flushed with solder. This leaves no +crevices in which bacteria and dirt can lodge, and makes cleaning easy. +The cleaning of the freezer should receive special attention. + + +=134. The effect of freezing and hardening on the bacterial +count.=--Authorities agree that there is an increase in the number +of organisms in ice-cream during the freezing process, as determined +by the plate method. This may be accounted for by the agitation in +the freezer breaking up the clusters of bacteria. This cluster would +give only one colony on a plate, but after being broken up might +result in several colonies. This is not a real increase in the number +of bacteria. The same holds true with other machines, such as the +clarifier.[41] + +[41] Hammar, B. W., “Studies on the clarification of milk,” Ia. Exp. +Sta., Res. Bul. 28, 1916; McInerney, T. J., “Clarification of milk,” N. +Y. Cornell Exp. Sta., Bul. 389, 1917. + +Ellenberger found that there were no radical changes in the total +number of bacteria in ice-cream during hardening. There seems to be a +tendency toward a slight decrease in the first two or three days with +a more noticeable increase and corresponding decrease again between +the sixth and twentieth days, after which there is only a very gradual +falling off in numbers. The lower temperatures may have a destructive +effect on some types of organisms. There may be a reorganization with +the survival of the fittest. + + +=135. Types of organisms in ice-cream.=--The bacterial flora of +ice-cream in summer and winter was studied by Ayers and Johnson.[42] +They divided the samples into summer and winter and the bacteria into +groups by the milk-tube method of differentiation. + +[42] Ayers, S. H., and Johnson, W. T., Jr., “A bacterial study of +ice-cream,” U. S. Dept. Agr., Bul. 303, 1915. + +TABLE IX + +Showing the Groups of Organisms and the Percentage in Each Group + + _71 Summer_ _28 Winter_ + _samples_ _samples_ + _per cent_ _per cent_ + Acid-coagulating group 49.82 30.84 + Acid-forming group 20.72 38.03 + Inert group 13.98 4.81 + Alkali-forming group 1.86 5.42 + Peptonizing group 13.62 20.90 + + +=136. The total-acid groups.=--“As seen in Table No. IX of the average +bacterial flora of summer ice-cream 70.54 per cent is made up of the +total group of acid-forming bacteria, and during the winter 68.87 +per cent. While using the milk-tube method of differentiation the +reactions of the litmus milk tubes are recorded after 2, 5 and 14 +days, and the total acid-forming group is composed of those bacteria +which produce acid in litmus milk during the 14 days’ incubation. Those +bacteria which form acid and peptonize the milk are included in the +peptonizing group. The total-acid group can be further divided into +those which produce acid and coagulate the milk and those which simply +form acid within 14 days. Since the reaction is recorded after 2, 5, +and 14 days, the rapidity of the growth of the acid-forming bacteria +can be determined, and this serves as an additional means of separating +the group. In Table No. X the percentages of the acid-coagulating and +the simple acid-forming groups of bacteria are shown, based on the 2, 5 +and 14 day reaction in litmus milk.” + +TABLE X + +Changes in the Percentage of the Total-acid Group of Bacteria in +Ice-cream when Determined by Litmus-milk Reactions after Various +Lengths of Incubation + + _Per cent reacting after_ + _incubation for_ + _Bacterial group_ _2 days_ _5 days_ _14 days_ + _per cent_ _per cent_ _per cent_ + Averages of 71 summer samples: + Acid-coagulating 26.31 41.52 49.82 + Acid-forming 35.43 25.58 20.72 + Average of 28 winter samples: + Acid-coagulating 8.20 25.02 30.84 + Acid-forming 44.51 41.30 38.03 + +“An examination of Table No. X shows that among the summer samples +49.82 per cent of the bacteria produced acid and coagulated the milk +after 14 days. After 2 days 26.31 per cent produced this reaction. This +shows that a little more than half, or 52.81 per cent of the bacteria +which were in the ice-cream produced the reaction within 48 hours. The +remaining 47.19 per cent coagulated milk more slowly and may represent +a different variety of acid-forming bacteria. Turning again to the +table and considering the acid-coagulating group of the winter series, +it will be seen that of the 30.84 per cent which produced the reaction +only 8.20 per cent produced acid and coagulated milk in 2 days. +Therefore only 26.69 per cent of the acid coagulating group of the +winter samples were active enough to produce the reaction in 48 hours, +while 52.81 per cent of this group in the summer samples brought about +the change in 2 days. + +“There is little to be said regarding the acid-forming bacteria which +simply produce acid. Many of them grow slowly and do not show an +acid reaction for several days in litmus milk. The milk-tube method +furnishes a means of determining the difference in the rapidity with +which the bacteria produce acid. As may be seen in Table No. X the +percentage of the acid-forming group of bacteria was highest when +determined by the 2-day reactions and lowest when based on the 5 and +14 days’ reactions. This is explained by the fact that many bacteria +have simply formed acid after two days in litmus milk and later may +coagulate or peptonize the milk, and are therefore thrown into another +group.” + + +=137. The inert group.=--“The inert group of bacteria in ice-cream +comprises those which produce no change in litmus milk during the 14 +days’ incubation at 30° C. (86° F.). By this method of grouping there +are, of course, included in the inert group those cultures which +fail to grow in milk and tubes of litmus milk, and which would also +be included even though the lack of growth were caused by failure to +inoculate the tubes properly. However, this last possibility is small. +The inert group is of little interest, on the whole, since the bacteria +produce no apparent change in milk, and in all probability the same is +true of ice-cream.” + + +=138. The alkali group.=--“The alkali-forming group of bacteria is made +up of organisms capable of producing an alkaline reaction and no other +apparent change in litmus milk during the 14 days’ incubation at 30°C +(86°F). This group does not include bacteria which produce an alkaline +reaction together with visible signs of peptonization. While there are +in the literature references which deal with types of alkali-forming +bacteria, this group has rarely, if ever, been considered when the +flora of milk has been under discussion. The authors in some previous +work on bacteria in milk showed that considerable numbers of this +group were present in milk. In a later piece of work we have shown the +numbers of this type of bacteria in milk, together with some of the +cultural reactions of the alkali-forming bacteria. These bacteria, +however, give very few positive reactions with the usual cultural +media, and it is impossible to give much information regarding this +group. A detailed bacteriological and chemical study of these organisms +is under way in the research laboratories of the Dairy Division. + +“It will be seen from Table XI that during the summer series of ice +cream samples the average sample contained 1.86 per cent of the alkali +group of bacteria, and during the winter series 5.42 per cent. In +general, the alkaline reaction is not noticeable until after four +or five days’ incubation in litmus milk. Occasionally, however, the +reaction is in evidence in 48 hours. This group percentage for the +summer season was 1.86 after 14 days and only 0.15 per cent based on +the 2-day reaction. Therefore, only 8.06 per cent of the bacteria of +the alkali group produce an alkaline reaction within 48 hours. Among +the samples collected during the winter season only 3.13 per cent of +the bacteria of this group were capable of producing the reaction +within two days. Whether this indicates a different variety of organism +can not be said with assurance.” + +TABLE XI + + Changes in the Percentage of the Alkali Group of Bacteria in + Ice-cream when Determined by Litmus-milk Reactions after Various + Lengths of Incubation + + _Per cent reacting after + incubating for_ + _Alkali group_ _2 days_ _5 days_ _14 days_ + _per cent_ _per cent_ _per cent_ + Average of 71 summer samples 0.15 1.03 1.86 + Average of 28 winter samples .17 4.00 5.42 + +“At present we are unable to state the significance of this group of +bacteria in milk and ice-cream, but it is evident that they are not +present in ice-cream in large numbers, as are the bacteria of other +groups. + +“Alkali-forming bacteria were not found in each sample examined, but +this does not prove that there were none present in the ice-cream. +Since these organisms are present in small numbers compared to the rest +of the bacteria, it is not surprising that none should be found on +plates in which the dilution had to be high in order to take care of +the large total number of organisms.” + + +=139. The peptonizing group.=--“The peptonizing group is probably +the most interesting if not the most important group of bacteria in +ice-cream. This group consists of what are commonly known as the +putrefactive bacteria; that is to say, they attack primarily the +proteins, decomposing them into less complex organic bodies. Bacteria +of this class are usually considered undesirable in articles of food, +and it is to them that intestinal troubles are sometimes attributed, +perhaps with or without justification. Whatever their true effect is +will not be discussed in this paper, but because bacteria of this group +are looked upon with suspicion it is therefore of great importance. + +“Among this group there are a large number of different types of +organisms. Many rapidly peptonize the casein of milk and render milk +alkaline or slightly acid, while others first attack the lactose and +only produce a slight peptonization after several days’ growth. From +the milk-tube method of differentiation of the bacterial groups it was +possible to gain some information as to the extent of these different +classes of peptonizers. In Table No. XII are shown the average +percentages of the peptonizing group in summer and winter samples of +ice cream. Based on the 14-day reaction among the summer samples, 13.62 +per cent of the bacteria belonged to the peptonizing group. According +to the 2-day reaction, there were 5.93 per cent. Therefore 43.54 per +cent of the peptonizing bacteria were sufficiently active to produce a +peptonization within two days. Among the winter samples 34.06 per cent +of the peptonizing bacteria were sufficiently active to peptonize milk +within 48 hours. These active peptonizing bacteria are more important +than the slower-acting varieties, since their peptonizing action is +usually more complete than that of the latter-named varieties, and if +any harm is produced by this group, they are most likely to be the +organisms concerned.” + +TABLE XII + +Changes in the Percentage of the Peptonizing Group of Bacteria in +Ice-cream when Determined by Litmus-milk Reactions after Various +Lengths of Incubation + + _Per cent reacting after + incubation for_ + _Peptonizing group_ _2 days_ _5 days_ _14 days_ + _per cent_ _per cent_ _per cent_ + Average of 71 summer samples 5.93 9.76 13.62 + Average of 28 winter samples 7.12 13.58 20.90 + + +=140. Colon bacilli in ice-cream.=--Since the presence of colon bacilli +has been understood in water analysis to indicate fecal contamination, +many investigators and boards of health apply the same tests to milk +and naturally then to ice-cream with the same idea. In water analysis, +lactose-bile fermentation tubes are employed for the examination for +colon bacilli. By using different dilutions, the maximum number of +gas-forming bacteria in a given amount of water may be determined. +This preliminary test has to be followed by confirmatory ones in which +cultures are isolated and their characteristics studied in order to +prove the presence of colon bacilli. Ayers and Johnson used this method +to some extent but endeavored to prepare a synthetic medium which would +restrict the growth of the larger number of bacteria in ice-cream and +at the same time would allow colon bacilli to develop and produce +characteristic reactions. Ice-cream contained a much larger number of +gas-forming organisms in the summer season. A large number of media +were used in an attempt to devise a suitable medium for the detection +of Bacillus Coli in ice-cream and the results show that there is no +entirely satisfactory method known at present. + + +=141. Difficulties in studying the bacteriology of ice-cream.=--As has +already been pointed out, one of the greatest difficulties in studying +the bacteriology of ice-cream is the lack of a suitable culture media. +Because of the low temperature at which the ice-cream is hardened and +held, some investigators believe that there is a gradual change of +the types of organisms or the survival of the fittest. This brings up +the question as to the temperature at which the cultures should be +incubated. Until a suitable media is prepared and a uniform temperature +of incubation used, the counts of the organisms in ice-cream made by +different investigators will not be comparable. + + + + +CHAPTER XIV + +_TESTING_ + + +The determination of the composition of dairy products is a very simple +yet important part of the ice-cream business. The fat and the solids +not fat are the constituents usually determined. The most accurate +method by which to buy all raw materials is on the basis of their +composition. The finished product should be tested to determine its +composition, regardless of whether or not it is sold on this basis. The +testing of the finished product is necessary to check up the amount of +materials used. By this means an accurate cost account can be kept and +any variation in the composition of the product quickly discovered. + + +THE BABCOCK TEST[43] + +[43] Troy, H. C., “The Babcock test and testing problems,” Cornell +Reading Course Lesson 118, 1916; Ross, H. E., and McInerney, T. J., +“The Babcock test with special reference to testing cream,” N. Y. +Cornell Exp. Sta., Bul. 337, 1913; Hunziker, O. F., “Testing milk and +cream for butter fat,” Ind. Exp. Sta., Circ. 42, 1914. + +The amount of fat in milk, cream and skim-milk can be ascertained +quickly and accurately by means of the Babcock test. The essential +requirements are that the operator be careful not to break the +glassware and that the measurements are accurately made. + + +=142. Testing whole milk for fat.=--The sampling is the most important +operation of the test. “The sample to be tested should be thoroughly +mixed before it is measured out. Mixing is done by shaking the vessel +in which the milk is contained, or better still, by pouring the milk +from one vessel into another. The fat in milk is lighter than the +other constituents and soon rises to the surface. Unless great care is +exercised an unfair sample will be taken. If the sample is an old one, +such as a composite sample, it should be heated to a temperature of not +over 85° F. in order to soften the fat. The sample should not be heated +above 85° F., since the fat is likely to separate in the form of an oil +and when so separated it is impossible to remix it evenly throughout +the sample.” + + +=143. Composite samples of milk.=--The purpose of taking composite +samples is to reduce the labor and expense of testing. The true +composite sample consists of aliquot portions of milk of several +deliveries from the same patron. Composite sample jars must have a +tight seal in order to prevent evaporation of moisture. Pint jars +sealed with glass stoppers, cork stoppers, metal caps or screw tops may +be used for this purpose. Bottles with paper caps and jelly glasses +with tin lids do not furnish tight seals; they should not be employed. + +A separate jar is used for each patron and each jar must bear the +respective patron’s number. The jars should be thoroughly clean and, in +order to guard against errors, they should be arranged on convenient +shelves near the weigh-can in numerical order, grouping the jars of +patrons of the same route together. Correct composite samples may be +obtained by the use of a milk thief or a graduated pipette. If the milk +thief is used, it is inserted into the weigh-can of milk of the entire +delivery of one patron. The milk in the tube rises to the level of +that in the weigh-can. The milk thief is then emptied into the sample +jar. In case the graduated pipette is employed, a certain quantity of +milk is taken for every pound delivered by the patron (usually about +.1 cubic centimeter for every pound of milk delivered). The milk thief +is the handier instrument of the two, but when the amount of milk +delivered by different patrons varies considerably, the samples of milk +from the larger producers are often too ample to be practical. + +[Illustration: FIG. 62.--Babcock milk pipette.] + +Other so-called composite samples are taken by using the same measure +for all milk receipts. In this case a small dipper holding about one +ounce is commonly employed. With this dipper a sample of milk is taken +daily from the weigh-can of each patron’s milk and transferred into the +sample jar. This method of composite sampling is not mathematically +correct and the results tend to be less reliable, although experimental +data show that the results average practically the same as when aliquot +portions are taken. Evaporation causes the percentage of fat and other +solids to increase, yielding misleading tests. It also tends to dry the +milk on the surface, causing the formation of a tough, leathery layer. +In this condition it is difficult to secure a representative portion +for the test. This can be prevented: by giving the sample jar a gentle +rotary motion after each addition of milk; by replacing the stopper +properly after each addition of the milk; and by protecting the sample +from excessive heat. Fermentation may be prevented by the addition of a +small amount of preservative, such as corrosive sublimate, potassium +bichromate or formaldehyde. It is usually best to have the temperature +of the milk from 60° to 70° F. when measured into the test bottle; +however, variation within reasonable limits will not affect the test +since the coefficient of expansion of the milk is not high enough +appreciably to affect the amount measured by the pipette. + +[Illustration: FIG. 63.--Babcock whole milk test-bottle.] + + +=144. Measuring the sample.=--The instrument for measuring the milk for +the test is called a pipette. (Fig. 62.) It has only one graduation, +17.6 cubic centimeters, equivalent to 18 grams. The sample is measured +by drawing the milk above the graduation and then placing the index +finger over the end of the pipette. By carefully releasing the finger, +the column of milk can be lowered until the bottom of the meniscus is +on a level with the 17.6 c. c. mark on the pipette. It is absolutely +necessary that the mark on the pipette be held on a level with the eye, +so as to show when the column of milk is on a level with the mark. +The milk is then transferred from the pipette to the test-bottle. +(Fig. 63.) The pipette and the test-bottle should be slanted so that +the milk will run down the bottle neck and not be forced out by the +air coming from the bottle. Whole-milk test-bottles are of two kinds, +those reading as high as 10 per cent and graduated in fifths, and those +reading as high as 8 per cent and graduated in tenths. In each case the +graduations give readings directly in terms of percentage, since the +graduated part of the neck is made to hold a column of fat which is a +definite percentage of the weight of the milk taken. + +[Illustration: FIG. 64.--Acid measures for Babcock test.] + + +=145. Adding the acid.=--Sulfuric acid is added to the milk in +the test-bottle, by means of a special measure which has only one +graduation, 17.5 cubic centimeters. (Fig. 64.) The purpose of adding +the acid is to destroy all the milk solids except the fat, which it +does by moist combustion. In this process great heat is produced. This +is advantageous, since the fat must be kept in a liquid condition in +order to perform the test properly. The neck of the test-bottle gives +percentage readings only when the fat is in a liquid condition. In +adding the sulfuric acid, the bottle should be slanted, the same as in +adding milk. As the acid is poured in, the bottle should be revolved +so that the acid will wash down any milk that adheres to the neck. If +this is not done, the milk dries on the neck and is lost in the test; +it also causes a cloudy bottle-neck and obscures the fat column when +the test is completed. The acid and milk should be mixed thoroughly as +soon as the acid is added to the bottle, else portions of the sample +might be charred and so lock up small particles of fat. It is well +to mix the contents of the bottle for at least half a minute after +all the milk has apparently been dissolved by the acid. The mixing is +done by holding the bottle by the neck between the thumb and the index +finger, and giving it a rotary motion from the wrist (Fig. 65); if an +up-and-down motion is used, the contents of the bottle are likely to be +spilled. + +The strength of the acid is reckoned in terms of its density, which +should be 1.82 to 1.83. A special instrument is used for testing the +density, and, since this instrument is seldom available in a dairy or +a creamery, one of the best ways of testing the acid is actually to +perform a test with it and note the results. The acid should be of such +strength that it will turn the contents of the bottle to a dark brown +as soon as mixed, and the mixture should turn an intense black after +standing for about one minute. The best acid is colorless, yet it may +be fairly dark and yet be fit for use. The acid should never contain +any undissolved material, since this is likely to rise with the fat and +obscure the reading. + +[Illustration: FIG. 65.--Diagram showing the motion and position of a +test-bottle while mixing the milk and the acid.] + + +=146. Whirling the sample.=--After the acid and milk are thoroughly +mixed, the samples are ready for whirling. The centrifuges used are +of three main types (Fig. 66), those driven by hand power, by steam, +and by electricity. The steam machines usually are considered best, +since with them it is easy to maintain the proper temperature during +the process of whirling. The hand and electric machines should perform +equally as good work, provided a high enough temperature is maintained +to keep the fat in a liquid condition. The frame of the hand machine +should always be filled with hot water before the bottles are whirled. +In case of the four-bottle machines, which have no frames, the bottle +cups, which are made large for that purpose, should be filled with hot +water. Great care should be taken to have the machines balanced; by +this is meant that for every bottle on one side of the machine there +should be a bottle on the opposite side. The machines should also be +well oiled, especially those driven by steam, which, because of the +heat, soon dry out. + +[Illustration: FIG. 66.--Hand and power Babcock centrifuges.] + +The sample is whirled for five minutes and then filled with hot water +to the base of the neck, then whirled for two minutes and hot water +again added so as to bring the fat within the graduated part of the +neck. The sample is then whirled for one minute in order to bring all +the fat into the graduated neck. Some operators of the Babcock test +make two separate runs instead of three, filling the bottles to within +the graduated neck after the first run. While this may give fairly +good results, it is better to make three separate runs as indicated +above and fill to the base of the neck the first time. This washes the +fat free from any sediment and gives a clearer reading than would +otherwise be obtained. + + +=147. Reading the test.=--The sample should be read at once, before +the fat column has had time to cool. In reading, the bottle should be +held between the thumb and the index finger and the fat column should +be on a level with the eye. The fat column in a whole-milk bottle is +not large enough to be greatly affected by temperature unless it is +extremely hot or cold. With a steam centrifuge, the temperature may be +extremely high and thus the reading may be slightly increased. This +danger may be avoided by allowing the bottles to stand for a minute at +room temperature before reading. There is greater danger of reading +the fat column at too low than at too high a temperature. It does not +take long for the fat column to harden, and if the room is at all cold +it is safer to set the test-bottles in water at about 140° F., having +the water come above the fat column in the bottle. The extreme points +of the column should be included in the reading (Fig. 67) since this +method makes up very closely for minute particles of fat which are not +brought to the surface during the process of testing. + +There are two methods of reading the percentage of fat in the neck of +the bottle. The first is to obtain the difference between the bottom +and the top of the fat column; if, for example, the bottom of the fat +column rests on the 1.7 per cent mark and the top on the 5.8 per cent +mark, the percentage of fat is 4.1 (5.8 - 1.7 = 4.1). The second method +of reading is to count the whole percentage and the tenth percentage +marks covered by the fat column. Some operators make use of dividers +in reading the fat column. The exact space covered is obtained, and +one point of the dividers is placed on the zero mark and the other +point against the graduated mark. The latter point will indicate the +percentage of fat. There is no objection to this method, provided the +fat column is never measured when it is above or below the graduations +on the neck of the bottle. This is often done, yet there is no +certainty that the space above or below the graduations is of the same +size as it is within the graduations; in fact, it is usually larger. It +is, therefore, easy to see the inaccurate results that may be obtained +by taking a reading when the fat column is without the graduated part +of the bottle neck. + + +=148. Appearance of a completed test.=--In a completed test the fat +should be straw-yellow in color; the ends of the fat column should be +clearly and sharply defined; the fat should be free from specks and +sediment; the water in the neck just below the fat should be clear; +and the fat should be in the graduated part of the neck. Some of the +defects and remedies are explained in the following paragraphs. + +[Illustration: FIG. 67.--Proper way to read the percentage of fat in a +Babcock whole milk test-bottle.] + +If the fat column is too dark in color, the acid may have been too +strong, or too much may have been used, or the temperature of the milk +and the acid may have been too high just before mixing, Mixing too +slowly might also permit charring of part of the fat. The charred or +darkened condition of the fat may be corrected to some extent by using +less acid, by cooling both milk and acid below 60° F. just before +mixing, and by rapid, vigorous mixing continued for about a minute +after all casein has been dissolved. + +If the fat column is too light in color, the acid was either too +weak or too cold. This condition may be corrected to some extent in +succeeding tests by using more acid and by having the milk and the acid +at a slightly higher temperature when brought together. + +If the acid is not of the correct strength (specific gravity 1.82 to +1.83), it will be difficult to obtain a correct test, but the trouble +may be overcome partially by using more acid when it is weak and less +when it is too strong. + + +=149. Care of the test-bottles.=--As soon as all the bottles are read, +they should be emptied. If allowed to stand until cold, they are more +difficult to clean. The cleaning will be accomplished much more easily +if the bottles are shaken violently up and down as the contents run +out. A viscous sediment is formed by the action of the sulfuric acid +on the milk, and the hot acid helps to loosen this if the bottles are +well shaken. All Babcock glassware should be kept clean and bright. +This can be done best by washing in hot water and washing-powder, and +then rinsing in hot water. If many bottles are employed, a block and a +top-board are very useful. The block has holes bored in it, of a size +just large enough to hold the bottles, and it may be made to contain +any desired number. The holes in the top-board are large enough to +admit the passage of the necks through them and the board rests on the +shoulders of the test-bottles. In using this block and board, a number +of bottles can be emptied at once and the hot bottles will not burn the +hands of the operator. + + +=150. Testing cream.=--In testing cream there are three main factors to +be considered: first, taking the sample; second, getting the correct +quantity of cream into the test-bottle; and third, correct reading of +the completed test. + + +=151. Cream testing apparatus.=--There are several forms and sizes +of cream test-bottles. (Fig. 68.) The six-inch nine-gram bottles are +preferable, especially for use in hand testers. This form has a scale +graduated to read from 0 to 50 per cent, the smallest scale divisions +equaling .5 of 1 per cent. + +The balance for weighing cream test samples should be sensitive to .1 +of a gram. There are several different types on the market. + +An ordinary four-quart pail would serve as a vat in which to bring the +fat in the cream test-bottle to the proper temperature before adding +the meniscus remover and reading the test. The vat should be of such +depth that when it is nearly full of water and the cream test-bottles +are placed upright in it, the upper surface of the water and of the fat +columns will be on about the same level. + +The thermometer should be of a form that registers each temperature +degree between the freezing and boiling points of water. That would +permit of its use for a variety of purposes. + +[Illustration: FIG. 68.--Babcock cream test-bottles.] + + +=152. Sampling cream.=--Cream differs from milk in containing a higher +percentage of fat. Cream testing 30 per cent of fat would contain 70 +per cent of skimmed-milk substance, or milk-serum. Before sampling, the +fat should be distributed evenly by thorough mixing or pouring. If the +cream is old or lumpy or some has dried on the container, it should be +warmed to about 95° F. and the lumps passed through a strainer before +mixing. Then about two ounces should be placed in the sample bottle. + + +=153. Making the cream test.=--The test sample must be weighed instead +of measured because: + +1. The percentage of fat and the specific gravity of cream vary widely, +and the weight of a definite volume would vary accordingly. + +2. Cream may contain bubbles of air or of carbon dioxide. + +3. Cream varies so widely in viscosity (sticky quality) that the amount +delivered or the amount remaining in the pipette would be unknown. + +In testing cream 9 grams are used. The bottle should be balanced on the +scales, and a 9-gram weight placed on the opposite side. The sample +is mixed thoroughly, and by means of a pipette the cream transferred +to the test-bottle until the scales exactly balance. About 9 cubic +centimeters of water are next added to the test-bottle. (This water may +be measured with sufficient accuracy in the acid measure by filling +it a little over halfway to the mark.) About 15 cubic centimeters of +the acid should be placed in the test-bottle, and the contents mixed +thoroughly. The cream and acid mixture should not turn black, but +should remain coffee color. About 15 cubic centimeters of acid give the +proper concentration to dissolve the solids not fat, since the fat +forms such a large part of the mixture and does not go into solution. +The bottles should be centrifuged and the water added exactly as in +testing whole milk. + + +=154. Tempering the fat and reading the percentage.=--When the last +whirling is completed, the test-bottles should be transferred to +the tempering vat containing water held at a temperature of 140° F. +The water should be tempered in advance, and should be deep enough +to surround the necks of the bottles to the top of the fat columns. +After four minutes the bottles should be taken from the water, and the +meniscus remover added at once by placing the tip of a dropping pipette +containing some of the substance against the inside of the bottle’s +neck, which is held in a slightly slanting position. The red liquid is +allowed to run slowly down the inside of the neck and spread over the +fat to a depth of about one-fourth of an inch. It should not mix with +the fat. + +[Illustration: FIG. 69.--Method of reading the percentage of fat in a +Babcock cream test-bottle.] + +The meniscus remover is made from a purified mineral oil that has been +colored red with alkanet root. It is sometimes called glymol. When +placed on the top of a fat column in a cream test-bottle, it flattens +the curved surface, which is known as the meniscus. The test should be +read immediately by subtracting the number on the scale at the bottom +of the fat column from the number at the line of division between the +fat and the meniscus remover. (Fig. 69.) Thus, if the bottom line of +the fat column reads 12 and the line between the meniscus remover and +the fat at the top, 39, the percentage of fat would be 27. + + +=155. Testing skim-milk.=--A special bottle is used for testing +skimmed-milk. (Fig. 70.) The graduated neck of the test-bottle has a +very small bore in order to measure the fat accurately. A second neck +with larger bore is attached to provide a convenient means of filling +the bottle. The smallest divisions on the scale usually indicate .01 of +1 per cent, but on some bottles .05 of 1 per cent. + +[Illustration: FIG. 70.--Babcock skim-milk test-bottle.] + +The same care is necessary in mixing and sampling skimmed-milk and +buttermilk that is required for whole milk, and the same pipette is +used in measuring out the sample. The skimmed-milk is added to the +test-bottle through the larger neck. Since a little more acid is +necessary thoroughly to free the fat in skimmed-milk, the measure +should be filled to about a quarter of an inch above the mark. About +one-half of the acid should first be added, and the mixture shaken +thoroughly; then add the remainder, and again shake it vigorously for +about a minute. One should avoid throwing undissolved casein into the +small neck while mixing the milk with the acid. The bottles are then +centrifuged and filled in the same manner as in testing whole milk, +except that the first whirling should be continued for ten minutes +instead of five, in order to bring up all the smaller fat globules. The +percentage of fat is read immediately on completing the final whirling. + + +=156. Modifications of the Babcock test for ice-cream.=--The Babcock +test as already explained cannot be used to test ice-cream, because it +contains a large percentage of sugar. This sugar would char or burn and +so interfere with the reading of the test. The following[44] are three +modifications of the Babcock test. + +[44] Sproule, W. H., “Cheese and butter-making,” Ont. Agr. Coll., +Guelph, Canada, Bul. 266, 1918. + + +=157. The glacial acetic and hydrochloric acid test.=--“A +representative sample of the ice-cream is taken and melted and +thoroughly mixed; a 9 gram sample is weighed into an 18 gram Babcock +cream test bottle. A mixture is prepared using equal parts of +glacial acetic acid and concentrated hydrochloric acid. Twenty cubic +centimeters of this acid mixture is added to the 9 gram sample of +ice-cream in the test bottle and is then well shaken. The bottle is +placed in a water bath of 120° F. to 130° F., and shaken at intervals +until a brown color appears. It is then placed in the Babcock +centrifuge and the test completed in the same way as for testing cream +and the reading multiplied by two.” + + +=158. The sulfuric acid test.=--“To make the test with sulfuric acid, +a 9 gram sample is weighed into an 18 gram test bottle. About 9 cubic +centimeters of lukewarm water is then added to dilute the sample, in +order to have about 18 cubic centimeters of mixture in the bottle. The +sulfuric acid is then added slowly, a little at a time, at minute +intervals, shaking well after each addition until a chocolate brown +color appears in the bottle. No definite amount of acid can be stated +as the quantity will vary with different ice-creams. As soon as the +chocolate brown color appears in the ice-cream a little cold water may +be added to check the action of the acid. The bottle is then placed in +the centrifuge and the test completed in the usual way. The reading is +multiplied by two.” + + +=159. Acetic and sulfuric acid test.=--“Weigh a 9 gram sample of +ice-cream that has been thoroughly mixed. About 9 cubic centimeters of +water are then added to dilute the sample. Add 5 cubic centimeters of +acetic acid and then add carefully 6 to 8 cubic centimeters of sulfuric +acid. Centrifuge, and then add water the same as in other tests. If +using an 18 gram bottle, multiply the reading by two, to obtain the per +cent fat in the ice cream. A 9 gram bottle which is graduated to give +the percentage of fat directly needs no correction when reading.” + + +=160. The lactometer.=--Because not only the fat but all the solids +are utilized in the ice-cream, it is important to know the amount of +total solids and the solids not fat in the milk. This is ascertained +by determining the specific gravity of the milk and knowing the +fat-content; the solids not fat can then be calculated. The specific +gravity of liquids is measured by an instrument called a hydrometer. +Its use is based on the fact that when a solid body floats in a liquid, +it displaces a volume of liquid equal in weight to its own. Hydrometers +are in many cases so made that the specific gravity can be read at the +point where the scale is even with the upper surface of the liquid. A +hydrometer especially adapted to milk is called a lactometer. There +are two in common use, the Quevenne and the Board of Health. + +_The Quevenne lactometer_ is a long slender hollow piece of glass +weighted at the bottom to make it float in the milk in an upright +position. (Fig. 71.) The upper end is slender and contains the scale +which is graduated from 15 at the top to 40 at the bottom. Each reading +on the scale corresponds to the point marked specific gravity on a +hydrometer, except that the figures are not complete. For example, 15 +on the Quevenne scale means a specific gravity of 1.015; a reading +of 30 means a specific gravity of 1.030, and so on. The Quevenne +lactometer is graduated to give correct readings at 60° F. The milk +should be at this temperature; if above or below this, a correction +must be made to the reading. The temperature should not be more than +10 degrees above or below 60° F. The correction for each degree in +variation can be made by adding or subtracting 0.1 from the lactometer +reading, as the case may be. If the temperature is above 60° F., the +correction is added to the lactometer reading; if below 60° F., it is +subtracted. The reading should be taken when the lactometer is floating +free in the milk. The scale is read exactly at the surface of the milk. +The better lactometers have a thermometer with the scale just above or +opposite the lactometer scale. + +[Illustration: FIG. 71.--Quevenne lactometer.] + +_The Board of Health lactometer_ is very similar to the Quevenne except +that the scale is graduated from 0 to 120. (Fig. 72.) The point on +the scale that floats at the surface in water is represented by 0, +and 100 represents the specific gravity of 1.029. On the Board of +Health lactometer the 100 degrees or divisions from 0 to 100 equal 29 +divisions on the Quevenne. Therefore, one division on the Board of +Health equals 0.29 of a division on the Quevenne. To convert Board of +Health reading to Quevenne, multiply by 0.29 and to convert Quevenne to +Board of Health, divide by 0.29. The correction for temperature above +or below 60 F. is made the same as with the Quevenne, except 0.3 is +added or subtracted from the lactometer reading instead of 0.1 as with +the Quevenne. + + +=161. Calculating the solids not fat in the milk.=--When the lactometer +reading and the fat-content of the milk are known, there are several +formulas for calculating the solids not fat. In the following, L equals +Quevenne lactometer reading at 60° F.; F. the percentage of fat in the +milk, and S. N. F. the solids not fat in the milk. + + L + 0.7F + -------- = S. N. F. + 3.8 + + L + F + ----- = S. N. F. + 4 + + L + - + 0.2F + 0.14 = S. N. F. + 4 + +[Illustration: FIG. 72.--Board of Health lactometer.] + + +=162. Testing milk for acidity.=--Several tests on the market are +used to determine the amount of acid in milk. Each is based on the +principle of chemistry, that acids and alkalies tend to neutralize each +other. The acidity of milk is of two kinds, apparent and real. The +apparent acidity is due to the acid reaction of the acid phosphates and +casein. It usually varies from .08 to .1 per cent. The real acidity +is due to the action of the bacteria on the milk-sugar. It is usually +assumed when determining the acidity of milk, that all the acidity is +due to the presence of the lactic acid. + +[Illustration: FIG. 73.--Nafis acid test.] + +The process by which the acidity is determined is called titration. +A known quantity of milk is placed in a cup or flask and an alkali +of known strength measured into it by means of a burette. (Fig. 73.) +The unit of measure is the cubic centimeter. The burette is usually +graduated into tenths of a cubic centimeter. The point at which all +the acid in the milk is neutralized by the alkali is told by means +of an indicator. The one commonly used is phenolphthalein. This is +colorless in the presence of acid and pink in the presence of alkali. +If two or three drops of indicator are put in the milk, the color will +not change because it is acid. When just enough alkali has been added +to neutralize the acid, the color will change to pink. The alkali +should be added slowly and gradually the acid will be neutralized by +the alkali until at last a uniform pink color appears, which will +slowly fade away. All the acid has been neutralized and the amount of +alkali used should be read from the burette, when the first change to a +uniform pink color is noted. + +The different acid tests on the market are sold under various trade +names, such as Nafis, Manns, Marschalls and Farringtons. Each is based +on the same principle but uses different amounts of milk and alkali +solutions of various strengths. However, in each test the amount of +milk and strength of the alkali solution are such that the number of +cubic centimeters of alkali used are read directly as the percentage of +acid in the milk. This eliminates all calculations. If the strength and +amount of the alkali solution required to neutralize the acid in the +milk is known, and the amount of milk used, accurately measured, the +percentage of acid can be calculated. + +It is a chemical fact that one cubic centimeter of a normal solution +of alkali will neutralize exactly .09 grams of lactic acid. In actual +practice an alkali solution weaker than a normal solution is employed. +This is because the latter is so strong that only a small amount +would be used, hence a small variation in the amount would make a big +variation in the final percentage. A ¹⁄₁₀ or ¹⁄₂₀ normal solution +(expressed n/10 or n/20) is commonly used. One cubic centimeter of a +n/10 alkali solution would neutralize .009 grams of lactic acid. An +example will illustrate how to figure the results. Suppose it took 4 c. +c. of n/10 alkali solution to neutralize the acid in 18 grams of milk. +What is the percentage of acidity in the milk? One cubic centimeter +of n/10 alkali will neutralize .009 grams of lactic acid. Four cubic +centimeters will neutralize 4 × .009 = .036 grams of acid; .036 grams +of acid divided by 18, the grams of milk used, multiply by 100, equals +.20 per cent acidity in the milk. This may be expressed thus: + + .009 × No. c. c. alkali used + ----------------------------- × 100 = per cent of acidity + number of grams material used + +Then the above problem would be expressed thus: + + .009 × 4 + -------- × 100 = .20 per cent acidity + 18 + + +=163. Test for formaldehyde.=--Sometimes formaldehyde is added to the +milk to preserve it. It can be detected easily when making the Babcock +test. The required amount of milk is measured with the pipette into +the test-bottle and a few drops of ferric chloride added. The required +amount of sulfuric acid is next put in. If formaldehyde is present, a +lavender-colored ring will appear between the layer of acid and the +layer of milk. If the contents of the bottle are slowly mixed, the +dissolving casein will take on a lavender color. The test will not +work if the milk is too old or too much of the formaldehyde has been +added. Because of the presence of ferric salts in the sulfuric acid +as impurities, it is not always necessary to add the ferric chloride +although it is best to do so. + + +=164. Test for boiled milk.=--It is often desirable to know whether or +not milk has been boiled. The following test will give this result: +Two sets of reagents may be used: (1) hydrogen peroxide, potassium +iodide and starch, (2) hydrogen peroxide and paraphenylenediamine +hydrochloride. In milk there is an enzyme glactase which may be +destroyed by heat. When the milk has not been heated, this enzyme +sets free the oxygen from the oxidizing agent. In case of the first +materials, the glactase splits up the hydrogen peroxide. The free +oxygen splits up the potassium iodide and liberates free iodine. The +starch in the presence of free iodine turns blue. In the second case, +the free oxygen acts on the paraphenylenediamine hydrochloride and +turns the solution blue. In either case if a blue color results, the +milk has not been boiled. Hydrogen peroxide often contains sulfuric +acid. When this is the case, the reagent is useless for the test with +starch as the free acid would break up the potassium iodide. If this +condition exists a blue color would result, whether or not the milk had +been pasteurized. + + +TESTING BUTTER FOR FAT, MOISTURE, AND SALT + +When large quantities of butter are used in the making of ice-cream, +it is important that it be tested. Sweet or unsalted butter is best +adapted for the making of ice-cream. If a sample is suspected or tastes +salty, a test should be made to determine the exact percentage. In +order to make cream of a desired percentage of fat, the composition of +the butter must be known. + + +=165. Preparing the sample.=--Experiments[45] indicate that the salt +and moisture in the butter are not uniformly distributed. This shows +the need of careful sampling and preparation of the sample before +testing. The sample should be placed in a wide-mouth ground-glass +stoppered glass jar. The bottle should be kept stoppered to prevent +evaporation. A hardwood stick is best for stirring. The bottle +containing the sample to be tested should be warmed to a temperature +of 110°-120° F. until the butter is the consistency of thick cream. +This may be done by placing the bottle in warm water. While it is being +warmed, it should be stirred to obtain a uniform mixture. It should not +be heated too much or the water and fat will separate and it is almost +impossible to mix them again. When the butter is about the consistency +of thick cream, it should be cooled and stirred thoroughly while +cooling. This insures a uniform composition in the butter. The cooling +should continue until the butter is quite firm. + +[45] Lee, C. C., Hepburn, N. W., and Barnhart, F. M., “Studies of +factors influencing the composition of butter,” Ill. Exp. Sta., Bul. +137, 1909; Guthrie, E. S., and Ross, H. E., “Distribution of moisture +and salt in butter,” N. Y. Cornell Exp. Sta., Bul. 336, 1913. + + +=166. Testing butter for fat.=--After the sample has been prepared to +test as outlined above, 3-5 grams of this butter should be weighed +into a cream test-bottle. The addition of warm water, warm enough so +that the fat will melt, will bring the weight of the butter and water +to approximately 18 grams. Sufficient acid to give a light brown color +should be added. It will take less acid than for cream because there +are fewer solids not fat. The procedure is the same as in testing cream +for fat. After the test has been read, the percentage of fat in the +butter must be calculated. + + +=167. Testing butter for moisture.=--Several moisture tests[46] are on +the market. The following is a very simple one: + +[46] Ross, H. E., “Butter moisture tests,” N. Y. Cornell Exp. Sta., +Bul. 281, 1910. + +The apparatus used is an alcohol lamp, iron stand, asbestos sheet, hot +pan lifter, aluminum cup for holding the sample, and a very sensitive +scale. To make the test, 10 or 20 grams of the prepared sample of +butter as described in paragraph 165, should be weighed into the +aluminum cup. The cup should be dry and about the same temperature as +the room. The alcohol lamp is then placed under the iron stand and +the asbestos sheet on the stand. The lamp is lighted and the cup put +on the asbestos sheet. It is well to light the lamp at least two or +three minutes before placing the cup on the asbestos in order to heat +it and save time. The heat of the flame may be increased or diminished +by raising or lowering the wick. The cup should always be handled with +the hot pan lifter, as by so doing it will be kept clean and errors in +weight due to dirt on the cup will be avoided. + +While the sample is heating, it should be shaken from time to time +as this breaks up the blanket of casein on the surface and hastens +the escape of moisture. As soon as the casein has lost its snow-white +color, the cup should be removed from the flame. When the moisture +has all been driven from the sample, a slightly pungent odor may be +noticed. This may also be used as a guide to tell when the sample has +been heated enough. The foam begins to subside at this point. Often one +or two small pieces of casein are slow to give up their moisture. This +is indicated by the snow-white color of the pieces. Evaporation can +be hastened by shaking the sample with a rotary motion and thoroughly +mixing these pieces with the hot liquid. If this is not done, one might +have to heat the sample so long that some of the fat, which had already +given up its moisture, would volatilize. + +After all the moisture is driven off, the sample is allowed to cool +to room temperature. While cooling, the cup should be covered with +something (a sheet of paper will do) to prevent the sample taking up +moisture from the atmosphere. After cooling, the cup is placed on the +scales. The sample is lighter than before heating, because it has lost +its moisture. The loss in weight divided by the weight of butter taken +gives the percentage of moisture in the sample of butter. + + +=168. Testing butter for salt.=--The following test has been devised +by H. C. Troy of Cornell. The materials used are: One ten cubic +centimeter burette graduated to tenths of a cubic centimeter; Babcock +milk pipette; one white cup; one pint bottle marked to show the line +at the upper surface of the liquid when the bottle contains 300 cubic +centimeters; standard tenth normal silver nitrate solution (dissolve +17.5 grams of so-called chemically pure silver nitrate in water and +make the volume up to 1000 cubic centimeters); 10 per cent solution of +potassium chromate for indicator. + +To make the test, three or four ounces of the butter should be softened +by warming to a pasty condition in a fruit jar or wide-necked bottle. +It should be mixed thoroughly with a table knife or strip of wood in +order evenly to distribute the moisture. Ten grams of the mixed butter +should be weighed into a dish and washed with hot water into the pint +bottle. (If a moisture test was made on ten grams of the butter, the +substance remaining in the cup may be used for the salt test.) Enough +hot water should be added to bring the surface up to the 300 cubic +centimeters mark on the bottle, the stopper placed in the bottle and +shaken vigorously for about half a minute. The bottle should rest for +about five minutes, and a Babcock milk pipette of the watery portion +drawn (17.6 cubic centimeters) and placed in a white cup. Three or four +drops of the potassium chromate solution should be added, stirred, +and run in the standard silver nitrate solution from the burette, +with constant stirring until the color of the substance in the cup +changes to a permanent brownish red. On the burette scale the amount of +standard silver nitrate solution used may be read. + +Each one-tenth of a cubic centimeter of standard silver nitrate +solution employed equals one-tenth of 1 per cent of salt in the butter. + + +=169. Test for viscosity.=--It is often desirable to test milk, cream +or the ice-cream mix for viscosity. There are several viscometers for +the purpose. The simplest way to determine the viscosity is to heat +and draw out the end of a pipette so that it has a very small opening. +The pipette can then be filled with the material to be tested. The +length of time required to empty the pipette determines the viscosity. +The more viscous the material, the longer it takes to run out of the +pipe. In order to make comparisons, the materials should be at the same +temperature each time. This is a very important factor. + + +=170. Standardization.=--One of the main requirements for a successful +ice-cream business is uniformity of quality. In order to obtain this, +it is necessary to have a product each time containing the same +percentage of fat. As it is impossible always to secure cream of a +uniform fat-content, the cream and milk used in the ice-cream must be +standardized.[47] + +[47] Ross, H. E., Guthrie, E. S., and Fisk, W. W., “Practical examples +in dairy arithmetic,” Cornell Reading Course, Vol. 5, No. 98. + +Standardizing milk or cream consists in raising or lowering the +fat-content to a fixed standard. This is done by adding to the +material milk or cream of a higher or lower percentage of fat. In +standardization two classes of problems are involved: first, one in +which a certain fixed amount of milk is to be made up or a certain +amount of standardized milk is desired; and second, in one in which +a certain amount of milk or cream is to be used and enough of another +product added to make the mixture test a certain percentage of fat. In +the latter case, the amount of the mixture is indefinite. + +The original method of computing problems in standardization is long +and difficult, but a comparatively simple scheme has been devised by R. +A. Pearson. The method is as follows: + +Draw a rectangle and place in the center of it the percentage of +fat desired. Place at the left-hand corners of the rectangle the +percentages of fat in the materials to be mixed. Subtract the number +in the center from the larger number at the left of the rectangle. +Place the remainder on the diagonally opposite right-hand corner of the +rectangle. Subtract the smaller number on the left-hand corner from the +number in the center and place the remainder on the diagonally opposite +right-hand corner of the rectangle. + +The two numbers on the right-hand corners of the rectangle represent +the number of pounds of material required. If these two numbers are +added they will express the number of pounds of the mixture, which +will contain a percentage of fat expressed by the number in the center +of the rectangle. In each case the number on the right-hand corner +corresponds in fat test to the number on the left-hand corner directly +opposite. + +[Illustration] + +Problem: How many pounds of 40 per cent cream and 3 per cent milk +must be mixed to make milk testing 5 per cent? Using the diagram as +described, the result shown in diagram above is obtained. + +This means that if 2 pounds of 40 per cent cream are mixed with 35 +pounds of 3 per cent milk, the result will be a 37 pound mixture +testing 5 per cent. Answer. + +Problem: How many pounds of 28 per cent cream and 3 per cent milk will +be required to make 500 pounds of a mixture testing 4 per cent? In this +problem a definite number of pounds of the mixture is required. + +[Illustration] + +According to the diagram, 1 pound of 28 per cent cream is required to +every 24 pounds of 3 per cent milk to make a mixture testing 4 per +cent. This would make 25 pounds of the mixture, but 500 pounds is the +amount desired. In other words, the number of pounds desired is 20 +times larger than the number of pounds on hand (500 ÷ 25 = 20). The +amounts must be kept in the proportion of 1 : 24. Therefore, in order +to get a 500 pound mixture it is necessary to multiply both the 1 and +the 24 by 20. This would give a result of 20 pounds of 28 per cent +cream and 480 pounds of 3 per cent milk, which mixed will equal 500 +pounds of 4 per cent milk. Answer. + +This problem may also be worked by simple proportion: + +1 : 25 :: x : 500 + +25 x = 1 × 500 + +25 x = 500 + +x = 20, number of pounds of 28 per cent cream there will be in the 500 +pound mixture. Answer. + +If there are 20 pounds of 28 per cent cream in the 500 pound mixture, +the remainder will necessarily be 3 per cent milk. + +Therefore, 500 - 20 = 480, number of pounds of 3 per cent milk. Answer. + +The number of pounds of 3 per cent milk can be found directly by simple +proportion: + +24 : 25 :: x : 500 + +25 x = 24 × 500 = 12,000 + +x = 480, number of pounds of 3 per cent milk. Answer. + +Proof: In working problems in standardization it is always wisest to +prove the answer, as this is the best method of checking the work for +mistakes. + +According to the conditions of the problem there would be 500 pounds +of 4 per cent milk. This amount of milk would contain 20 pounds of fat +(500 × .04 = 20). According to the results the 500 pounds would be made +up of 480 pounds of 3 per cent milk and 20 pounds of 28 per cent cream. +The 480 pounds of 3 per cent milk would contain 14.4 pounds of fat (480 +× .03 = 14.4). The 20 pounds of 28 per cent cream would contain 5.6 +pounds of fat (20 × .28 = 5.6). 14.4 + 5.6 = 20 + +Since the 500 pounds contain 20 pounds of fat, and the materials of +which the 500 pounds are made up furnish the 20 pounds of fat, the +problem is worked correctly. + +Problem: How many pounds of 3 per cent milk must be mixed with 150 +pounds of 28 per cent cream to make a mixture testing 4 per cent? In +this problem the number of pounds to be made up is not definitely known. + +[Illustration] + +Working the problem by the rectangle method, 1 part of 28 per cent +cream is required for 24 parts of 3 per cent milk. According to the +terms of the problem, 150 pounds of 28 per cent cream must be used, and +this is 150 times as large as in the above proportion. + +The 28 per cent cream and 3 per cent milk must be kept in the +proportion of 1 : 24, and since the amount of 28 per cent cream is to +be increased 150 times, the 3 per cent milk must also be increased 150 +times. This would give 150 pounds of 28 per cent cream (1 × 150) and +3600 pounds of 3 per cent milk (150 × 24 = 3600), making in all 3750 +pounds (150 + 3600 = 3750) of a 4 per cent mixture. + +This problem may also be worked by simple proportion: + +24 : 1 :: x : 150 + +x = 3600, the number of pounds of 3 per cent milk required. + +Proof: The 3750 pounds of 4 per cent milk will contain 150 pounds of +fat (3750 × .04 = 150). + +If the 150 pounds of 28 per cent cream and 3600 pounds of 3 per cent +milk furnish 150 pounds of fat, the problem is correct. + +3600 × .03 = 108, number of pounds of fat in milk. + +150 × .28 = 42, number of pounds of fat in cream. + +108 + 42 = 150, number of pounds of fat in mixture. Answer. + +The percentage of fat, or solids not fat, or total solids in a given +batch may be computed if the percentage composition of the materials +is known. Compute the total number of pounds of the desired material +in each of the products used and divide by the total weight of the +batch. For example, to find the percentage of fat in a batch, compute +the pounds of fat in each material and find the total number of pounds +of fat. Dividing the result by the total weight of the mix will give +the percentage of fat in the mix. The solids not fat or total solids +may be computed in the same way. By reversing these calculations, the +percentage of fat necessary in the milk or cream to yield a mixture +containing a certain percentage of fat can be computed. + +[Illustration: FIG. 74.--Apparatus for testing ice-cream over-run by +the Benkendorf method.] + + +=171. Benkendorf[48] test for over-run in ice-cream.=--With this simple +outfit (Fig. 74), it is possible at all times and without data as to +the volume or weight of the “mix,” for the manager of the factory to +determine the over-run in any lot of ice-cream made by his employees. + +[48] Benkendorf, G. H., et al., “Some improved dairy tests and +methods,” Wis. Exp. Sta., Bul. 241, 1914. + + +_Method of making the over-run test._ + +To obtain a 50 cubic centimeter sample, the metal sampler should be +pressed down into the hardened ice-cream until it is entirely below +the surface, and allowed to remain there for a minute or two, to become +chilled. Then it should be drawn out and the protruding ice-cream +removed from both ends of the sampler with a case knife or small piece +of flat metal. (When a continuous freezer is used, a metal sampler with +a closed bottom, like a cup, can be held under the spout of the freezer +until heaping full, then the surplus scraped off.) + +The 200 cubic centimeter flask should be filled exactly to the mark on +the neck with hot water and the sampler held in the funnel, the stem +of which is inserted in the neck of the 250 cubic centimeter flask, a +little of the hot water poured over the sampler until the ice-cream +slips out of it, then all the remaining hot water slowly poured over +this. + +The foam which appears in the neck of the 250 cubic centimeter +flask should be destroyed by adding 1 cubic centimeter (or 2 cubic +centimeters if necessary) of ether with the pipette. As soon as the +foam has disappeared, the flask may be filled with water exactly to the +250 cubic centimeter mark by means of the burette, which has previously +been filled to the zero mark. + + +_How to make the calculations._ + +The number of cubic centimeters of water and ether used to bring the +volume up to the 250 cubic centimeters mark, represents the shrinkage +which the 50 cubic centimeter sample of ice-cream has undergone when +melted. Subtracting this shrinkage from 50 gives the original volume +of the “mix” before freezing. To determine the percentage of over-run, +the number of cubic centimeters of shrinkage should be divided by the +number of cubic centimeters that were in the original mixture. + + _Example:_ _Cubic centimeters_ + Sample used 50 + Ether used to reduce foam 1 + Water used to bring to 250 c.c. mark 15.5 + Water and ether used (15.5 + 1) 16.5 + Volume of “mix” before freezing (50 - 16.5) 33.5 + Per cent of over-run (16.5 ÷ 33.5) 49.25 per cent + + +=172. Test to determine the hardness of ice-cream.=--The apparatus[49] +used for determining hardness was reproduced from the description of a +similar piece of apparatus by A. E. Perkins. It consisted of a wooden +frame made of 2 × 4-inch lumber, with cross pieces on the bottom so +that it stood firmly in an upright position. A cross piece, about one +foot from the bottom of the frame, made the support for holding the +sample. At the top of this support was an adjustable wooden screw +for holding the electro-magnet. By adjustment with this screw, the +magnet could be lowered or raised several inches. This adjustment was +necessary so that the height of the needle could be made constant with +all samples. The drop frame which holds the needle and which is held up +by the magnet until the electric current from the batteries is broken, +was made from very light ³⁄₈-inch piping, the width being sufficient to +give a free drop without touching the mold, and long enough to reach +below the platform when the magnet was at its highest point. The wires +from the magnet led to a cut-off key on the side frame and from there +to a pair of dry cells from which the current was derived. The needles +were of different sizes but the same weight, thus eliminating the +necessity of adjustments to obtain constant weight. The needles were +marked from their points upward, in centimeters and fractions thereof, +to show the depth of penetration. The height of the drop was always 100 +millimeters, being measured carefully with a metric rule before each +determination. + +[49] Holdaway, C. W., and Reynolds, R. R., “Effects of binders upon the +melting and hardness of ice-cream,” Va. Exp. Sta., Bul. 211, 1916. + +In making the determination, the frame with a suitable needle and +weights is suspended from the electro-magnet, and the material to +be tested placed in position beneath the needle, the height being +regulated as already described. The frame is then released by means of +the key. The depth of penetration is ascertained from the marks on the +needle and confirmed by measuring with the metric rule. The suspension +of the weights far below the needle brings the center of gravity of +the falling portion of the apparatus below the point of the needle, +causing the latter invariably to assume a vertical position, rendering +it much easier to ascertain the true depth of penetration than would +be the case if the point of the needle were at or below the center of +gravity. After its release by the electro-magnet, the apparatus meets +with no resistance in its fall, except that offered by the air, until +the point of the needle reaches the surface of the cream. The amount +of weight acting on the needle is known and the distance through which +it falls is constant. If, however, too much weight or too small a +needle is employed, the latter continues to sink slowly, making an +accurate reading of the depth of penetration impossible. In the reverse +case, with too large a needle or too little weight, the penetration +is of course much less and the percentage of experimental error +proportionately greater. As there was a large variation in the hardness +of the various fillers, three sets of needles were employed and in this +way much of the error was eliminated. The size of the needles were: +large ⁵⁄₁₆ inch or 7.93 millimeters, medium ⁴⁄₁₆ or 6.35 millimeters, +and small ³⁄₁₆ or 4.76 millimeters in diameter. The tests were made +by allowing each needle to penetrate the ice-cream three times. The +point of penetration was varied from center to points near the edge as +there was a possibility of the cream being harder near the edge than in +the center. The depth of penetration of each needle was expressed in +millimeters. The work was done in a cold storage with the temperature +near 0°C. + +[Illustration: FIG. 75.--Mojonnier tester for fat and total solids.] + + +MOJONNIER TESTER + +Considerable time is required to make some of the tests, after the +chemical method, such as those for solids in the different milk +products. Mojonnier Brothers have devised a test both for fat and +solids which is accurate and saves much time. A description of this +test follows. The machine is shown in Fig. 75. The numbers on the +arrows refer to numbers in the text, as follows: + + (1) All tests for butter-fat are made upon this side. + + (2) All tests for total solids are made upon this side. + + (3) Butter-fat extraction flasks in centrifuge baskets. + + (4) Eight 3½ inch aluminum dishes for butter-fat tests (the larger + ones). The one tall counterpoise counterbalances each dish. Fat + dishes have no covers. + + (5) Eight 3-inch aluminum dishes for solids tests (the smaller ones). + The one short counterpoise counterbalances each dish. Cover prevents + absorption of moisture from the air during weighing. Counterpoise + balances both dish and cover. + + (6) Fat vacuum oven. The temperature in this oven is maintained at + 135 deg. C. Thermometer (10) extends into vacuum oven and rests on + hot plate. The mercury bulb fits snugly in removable brass mercury + well. Once a month this mercury well should be refilled with mercury. + Be careful to see that the well always forms good contact with hot + plate. Regulate temperature by rheostat (15). + + (7) Cooling chamber. Water at room temperature from the tank (28) in + bottom part of the fat tester, is pumped by means of circulating pump + in power unit (20) through the flat hollow sheet brass plate inside + the cooling chambers and from there into pipe back of tester back + into tank. Operator must watch outlet on cooling chamber and see that + water is flowing at all times while the motor is turned on. If water + is not running, you may know that the water in the storage tank is + low. Keep tank filled at all times. In winter to prevent freezing, + put a gallon of denatured alcohol into tank. + + (8) Solids oven. Maintained at 100 deg. C. Regulate temperature by + means of rheostat (16). Follow instructions in (6) above closely for + method of placing thermometer. Keep joints at door clean, and grease + with vaseline sliding surfaces. This insures a more perfect vacuum. + + (9) A 250 deg. C. thermometer for solids oven. Wire on rubber + connections. + + (10) A 250 deg. C. thermometer for fat oven. + + (11) Vacuum gauge is on main suction line from vacuum pump. This + registers vacuum of either oven, or of both ovens simultaneously. + + (12) Solids plate. Maintained at 180 deg. C. The thermometer can be + placed in nickel plated mercury well with base that rests directly + upon plate. See that this side is level. + + (13) Fat plate. Maintained at 135 deg. C. During the evaporation of + ether from the dishes, the temperature falls. Some operators prefer + to keep temperature at 150 deg. C. to start and place dishes only + halfway upon plate. As the plate cools, the dish may be pushed over + until it is entirely upon hot plate. + + (14) Rheostat for fat plate. Turning rheostat handle forward + increases temperature. Turning handle backward decreases temperature. + It is important to see that the lever on handle makes good contact + with separate buttons and not with two buttons at a time. As soon as + right button has been found that maintains constant temperature, mark + this point upon rheostat rim. In starting up tester, each day, you + may turn handle on full and then when temperature is up to within 10 + degrees of right point, turn handle back to previously marked button. + Same instructions apply for all rheostats. + + (15) Rheostat for fat oven. + + (16) Rheostat for solids oven. + + (17) Rheostat for solids plate. + + (18) Handle for centrifuge. + + (19) In case the operator forgets temperature and time for treating + samples at various points, he may notice the temperature and time + below each snap switch for each hot plate. + + (20) The power unit consists of a high vacuum pump, a water + circulating pump, and a suction fan all driven by a single motor. + Vacuum pump must be submerged in oil furnished with tester. Fill + chamber up to air cock with oil. + + (21) Automatic burettes. The cans holding the water, ammonia, + alcohol, ethyl ether and petroleum ether are placed in this order. + This is the order in which these reagents are added to the flasks + containing the weighed sample of milk. Each division delivers the + proper amount for a single extraction. + + (22) Place this hood over fat dishes when evaporating off ether, so + that the suction fan may draw off ether fumes to outside of building. + + (23) Fasten these legs to floor with lag screws. + + (24) This side need not be fastened to floor. In case it is + necessary to take out power unit, it is necessary only to disconnect + connections in rear of machine and move this part of machine forward. + + (25) The balance is the heart of the machine. Operator must keep it + level, clean and handle it carefully. Raising and lowering knife + edges must be done gradually and with care. Make it a habit of + cleaning balance daily. The weights must be kept clean, and as soon + as you notice that some of the smaller weights are wearing out, order + new ones. + + (26) This cock exhausts vacuum from oven when cock (27) is closed. It + must be kept closed when vacuum is turned on oven. + + (27) This cock puts vacuum from main line into vacuum oven. Set of + cocks at right is for solids oven, and at the left for fat oven. + + (28) In top of fat plate holder there is a hole communicating with + suction fan on power unit. When the exhaust pipe on suction fan is + run out of window of laboratory and the hood is over the dishes, all + fumes of ether will be driven from the room. + + (29) Screw stool to floor. + + (30) A wash stand for washing all glassware should be provided. + + +=173. General preliminary information.=--In the operation of the +Mojonnier tester, several steps remain the same regardless of the +product being tested. Among these are the following: + + + (1) _How to use the balance._ + + Two types of balances are in principal use--namely, the old type with + graduated beam and rider, and the new type called “Chainomatic” with + the chain and vernier. The care to give to either type of balance is + the same. The difference is in the method of balancing the object to + be weighed, and of reading the weight. These points will be discussed + separately. + + A balance is a delicate instrument, and care needs to be exercised in + its use at all times. The weights likewise require careful handling. + Lack of care in the weighing operations may lead to entirely + erroneous results, and thus defeat the object aimed at, namely, + accuracy of the tests. + + The balance is inclosed in a glass case to shield it from dust, + air currents, and moisture. Perhaps the largest factor affecting + accuracy in weighing,--granting other conditions to be right, is + temperature. If the object to be weighed is of a lower temperature + than the balance case, it will weigh apparently more than its actual + weight. If of a higher temperature than the balance case, it will + weigh apparently less than its actual weight. The object should, + therefore, be as closely as possible of the same temperature as that + of the air in the balance case. The water cooled desiccator used upon + the Mojonnier tester has been designed primarily to facilitate the + equalizing of the temperature between the dishes to be weighed and + the balance case. See, therefore, that the temperature of the water + in the circulating system is as nearly as possible the same as the + temperature of the balance case. + + All parts of the balance and weights should be kept free from dust. + A cover to be placed over the balance case at night serves a very + useful purpose. Use a camel’s hair brush to remove the dust from + both the balance and the weights. A small beaker partly filled with + sulfuric acid should be kept in one corner of the balance case. + Replace the sulfuric acid when it becomes saturated with moisture. + + Protect the balance against vibration, and see that it is in exact + level. The air bubble in the spirit level should be in the exact + center. This can be readily accomplished by means of the leveling + screws under the balance case. + + The balance should be in exact equilibrium at all times. That is, the + pointer should oscillate an equal number of divisions on each side + of zero upon the pointer scale. If the pointer swings too far to the + right, turn the adjusting screw upon the beam to the right. If it + swings too far to the left, turn the adjusting screw to the left. + + Place object to be weighed upon the left hand pan, and the weights + or counterpoises upon the right hand pan. Handle the weights with + the forceps only, using the right hand. Use the left hand to release + the beam from the support, and to raise or lower the balance door. + The weights should be placed upon the pan in a systematic order, + beginning with a weight that is judged to be somewhat too heavy. + Lower weights are then tried in succession in a systematic order + until equilibrium results. + + Upon the old style balance, adjustments under 5 or 10 milligrams + (depending upon the construction of the balance) are made by means of + the rider. Keep the balance door closed while the final adjustment + is being made. Determine the relation between the divisions upon + the rider beam, and the pointer scale. This relation varies with + different balances, but when once ascertained upon a given balance + it remains a constant value, and if applied in making a weighing, + a great deal of time can be saved. For example, if the pointer + oscillates six divisions to the right of zero, and four divisions + to the left, with a balance having a relation of .0002 gram to one + division upon the pointer scale, the rider is moved .0004 gram to the + right to bring the balance into equilibrium. + + Upon the Chainomatic balance, adjustments under .0500 gram are made + by means of the screw and vernier. Determine the relation between the + divisions upon the vernier, and the pointer scale. If the pointer + swings too far to the right, lower the slide,--if too far to the + left, raise the slide. About .003 gram upon the vernier usually + equals one division upon the pointer scale. + + Exercise great care in recording the weights. A double check should + be made by reading both the weights upon the balance pan, and the + weights that are missing from the set. The weights should be placed + upon a paper near the front of the balance case, with the values of + the weights marked upon the place where the respective weights are + kept. Remember that one misread weight will spoil an entire test. + Upon the Chainomatic balance read weights as follows: + + (a) Sum of all gram weights equals whole number. + + (b) Sum of 100 or multiple of 100 milligrams equals first decimal. + + (c) Sum of 10 or multiple of 10 milligrams equals second decimal. + + Out of a possible total of 100 milligrams, 50 milligrams are obtained + from the fractional weight, and 50 milligrams from the vernier beam. + + (d) The third decimal is obtained from the vernier beam. Read the + value of the line just above the small 0 upon the slide. + + (e) The fourth decimal is the value upon the slide that is in an + exact line with any given line upon the vernier beam. + + + (2) _Care to give to the power unit and the water circulating unit._ + + Keep the water tank well filled with water. Add about one quart light + machine oil to the water in the tank to keep the water pump well + lubricated. If the tester is located in a cold room in winter, add + one gallon denatured alcohol to the tank to prevent freezing. + + Keep the vacuum pump chamber properly filled with the right kind + of oil. The oil should just about reach the top of the pistons, as + indicated by the glass upon the side, or cock upon the end. + + Give the motor proper care. It should receive the same attention + as given to any motor, that is, it is to be kept cleaned and well + lubricated. + + Should any knocks develop upon the power unit, remedy the same + immediately. The construction is very simple, and with a little + study, the care and operation of the power unit should be readily + learned. + + + (3) _Care to give to the vacuum ovens and coolers._ + + Keep sufficient mercury in the mercury well to insure good contact + between the thermometer and the mercury well. The mercury well should + rest directly upon the hot plate. Otherwise incorrect temperature + will be indicated by the thermometer. Keep the ground joint between + the lid and the oven thoroughly cleaned. In case that it is difficult + to get the proper amount of vacuum, look first to this place for + trouble. Sometimes it may be necessary to use a small amount of + vaseline, but as a rule, the best results are obtained by keeping the + ground joints thoroughly clean. Be sure that the thermometer opening, + and the openings upon the bottom of the oven are thoroughly sealed. + It may be necessary to replace the rubber tubing at these points in + case that leakage develops. + + Be sure to see that the cooling desiccators are kept from freezing + temperatures. If the water in the cooling plates should freeze, it + would ruin the plates. Watch the water coming out of the coolers, in + order to be sure that the circulation is correct. + + + (4) _General care of the tester._ + + Keep the tester clean and free from the accumulation of unnecessary + material at all times. It is impossible to do accurate work if the + apparatus is not in the best of condition. All japanned parts can + be cleaned either with engine oil, applied to a clean cloth, or by + washing with good soap and water. + + + (5) _How to clean the dishes and the glassware._ + + The solids dishes should be soaked in water after the test has been + completed, and the solids then removed by means of a brush suited + to the purpose. They should then be thoroughly cleaned and dried, + and placed in the vacuum oven until required for further use. The + fat dishes should be treated with a small quantity of gasoline until + the fat is all dissolved, and this treatment repeated a second time. + Finally, the dishes are to be cleaned with a dry cloth, and placed in + the vacuum oven until needed. Do not use any water upon the fat dish. + + All glassware should be washed either immediately after being used, + or it should be placed in water until washed. Extraction flasks + should be thoroughly washed with tap water and then washed out with + distilled water. If flasks become dirty, wash with washing powder + and shot, or use washing powder with a brush specially designed for + this flask. Clean pipettes with brush and water. Use washing powder, + if necessary. Rinse successively with water, alcohol, and ether, and + then dry by holding at exhaust cock leading to the vacuum oven, or + place upon pipette holder between fat oven and cooler. + + + (6) _How to heat the dishes before weighing._ + + Give both the solids and the fat dishes the same treatment before + weighing the same empty as is given to them when the same are to be + weighed with the solids or the fat respectively in the same. Do not + attempt to weigh dishes that have not been heated previous to being + weighed. + + + (7) _How to cool the dishes._ + + Transfer the solids and the fat dishes from the respective vacuum + ovens to the respective coolers, and weigh the same as rapidly as + possible. Weigh the solids dish with the cover on, and the fat dish + without any cover. + + + (8) _How to adjust temperatures._ + + The temperatures upon the two outside hot plates and the two vacuum + ovens can be closely regulated by means of the rheostats. If the + voltage is constant, the temperature will remain very near to the + point desired for a long period of time after the rheostats have been + properly adjusted. Ascertain by test, just where it is necessary to + hold the rheostat in order to get the required temperature. After + this point is once ascertained, the rheostat can be set at the point + required and the temperature allowed to come up automatically, when + starting in the morning. + + + (9) _How to prepare the samples._ + + Care and good judgment requires to be exercised in preparing samples + of the various dairy products preparatory to weighing out samples of + the same for the test. This is explained more in detail in the more + extended descriptions following the various products outlined in + these directions. + + + (10) _How to weigh samples for the fat test._ + + Several methods are in use for weighing the samples for the fat test, + depending on the product that is being tested. The weighing cross + with the short pipettes can be used successfully on a number of + dairy products. Numerous advantages are gained by using this method, + provided the product to be tested permits of its use. Five different + samples can be weighed with only six weighings, and if care is taken, + great accuracy is obtainable. Several products can be pipetted out, + taking ten grams and where possible, this is a very accurate method. + The pipettes are graduated to discharge ten grams of whole milk at + 60 deg. F., allowing 15 seconds for draining the pipette after the + milk has all run out, and then blowing out the last drop of milk in + the pipette. Again, when sample shows signs of separation of fat, + the only satisfactory method is to warm up the sample until the fat + is melted, and mix thoroughly. While stirring the well mixed sample, + pipette out a sample into a cleaned, dried and weighed extraction + flask suspended from the balance beam. If flask is wet on inside it + should be weighed with cork. + + + (11) _Size of samples to take for the fat test._ + + The size of sample to use varies, depending on the product being + tested, and it ranges from one gram in the case of butter, to ten + grams in the case of raw milk. See instructions in diagram. + + + (12) _How to add the reagents._ + + The reagents should be added in the following order: Water, ammonia, + alcohol, ethyl ether and petroleum ether. The burettes upon the + dispensing cans are graduated to deliver the proper charge required. + See instruction diagram. + + + (13) _How to shake the flask._ + + If only one sample is being tested, this can be shaken by hand. + As many as four samples can be shaken at one time in the shakers + furnished with the equipment. The flask should be held with large + bulb down and small bulb extending upward. In this position they are + shaken vigorously lengthwise of flask. After shaking five or six + times, allow liquid in small bulb to run back into large bulb. Repeat + this operation at least four times. There is no danger in shaking the + samples too much, but rather of not shaking them enough. + + + (14) _How to centrifuge the flask._ + + If only one sample is being centrifuged at a time, place a + counterpoise upon the opposite side of the centrifuge in order to + balance the head. Always see that there is about the same weight upon + both sides of the centrifuge. + + + (15) _How to pour off the ether solutions._ + + Remove the cork by twisting carefully from the flask. Pour off the + ether solution as completely as possible, taking care not to allow + any of the liquid under the ether to flow out of the flask. This can + be avoided if the dividing line between the ether solution and the + remaining solution is carefully watched, while pouring off. In the + first extraction, a larger amount of the ether solution can remain in + the flask than in the second extraction. In the second extraction the + fat dish should be placed on the tester top, and the operator should + look down on the ether solution as it is being poured off, observing + the point where the ether has been all removed. By following this + method, all but one or two drops of the ether solution should be + recovered, provided the dividing line was in the right place before + pouring off. + + + (16) _How to bring up the dividing line._ + + Inability to pour off the ether solution closely is due to the fact + that the dividing line between the ether solution and the remaining + solution is too low in the lower bulb of the flask. At the end of + the first extraction, the dividing line can remain without change, + taking care to pour off the ether solution as closely as possible, + regardless of the position of the dividing line. At the end of the + second extraction, remove the stopper from the flask, and drop in + sufficient distilled water from the burette into the extraction flask + to raise the dividing line to the desired point. This should be done + just before pouring off the ether. If this procedure is followed, it + becomes possible to remove the ether almost to the last drop. + + + (17) _How to evaporate the ether from the dish._ + + It is important to maintain the proper temperature upon the outside + hot plate. If the temperature is allowed to go below 135 deg. it + takes too long to evaporate the ether solution. On the other hand, + if it rises much above 135 deg. there is danger of the ether boiling + out over the top of the dish. If the plate is too hot, it is best to + place only part of the dish in contact with the plate. We recommend + that the hood be placed over the dishes, and that the ether fumes + be blown out of the room by means of the blower. It is dangerous to + allow the ether fumes to evaporate into the working room, and besides + it makes it very unpleasant for the operator to work in contact with + these vapors. + + + (18) _How to heat the fat dish in the oven._ + + Do not transfer the fat dish to the vacuum oven until all of the + ether solution has been evaporated upon the outside plate. If this + is not done, the contents of the dish are quite likely to spatter in + the oven. It is very important to maintain the proper temperature + conditions, and also the proper vacuum upon the fat dishes, while + the same are being heated in the oven. If for any reason, there + should be difficulty in attaining either the proper heat or the + proper vacuum, the trouble should be immediately investigated and + removed. + + + (19) _How to weigh the fat dish._ + + The fat dishes are to be transferred from the vacuum oven to the + cooler, in which they are to remain for seven minutes before being + weighed. The weighing should be done as promptly as possible. + + + (20) _How to calculate the percentage of butter-fat._ + + Divide the weight of the butter-fat by the weight of the sample + taken. Multiply the result thus obtained by 100 in order to arrive at + the percentage of butter-fat in the sample. + + + (21) _Weight of sample to take for the solids test._ + + This varies with the product to be tested, ranging from .25 of a gram + in the case of sweetened condensed milk, to 2 grams in the case of + fresh milk. + + + (22) _How to weigh the solids sample into the dish._ + + The samples can be weighed from the weighing cross, or in several + cases it is advantageous to weigh the samples directly into the + solids dish. + + + (23) _How to add water to the samples in the dish._ + + For this purpose, always use best distilled water. It is well to run + a blank upon the water to determine if it is free from solid matter. + Reject any water that may contain any solid matter. Add sufficient + water to make up the total volume, not to exceed 2 cubic centimeters. + Agitate the sample with the water in the dish so that the remainder + will be uniformly distributed over the bottom of the dish. + + + (24) _How to treat the sample upon the outside hot plate._ + + It is very important to have the outside hot plate as nearly 180 + deg. as possible. If the temperature is less than 180 deg. there + will be insufficient bubbling of the sample, so that the surface + will be improperly broken. If a temperature above 180 deg. is used, + there is great danger of the samples spattering out of the dish. + Heat the samples in the dish until they just begin to turn brown. + This is one of the most important steps in the entire operation, and + unless properly watched, an error may be introduced at this point. + Insufficient heating may give high results, and over heating may give + low results. + + + (25) _Temperature and vacuum to maintain in solids oven._ + + Keep the solids oven at a temperature of as nearly 100 deg. as + possible. This applies to all products to be tested. Also see that + there is at least 20 inches of vacuum upon the vacuum oven. If the + tester is properly operated, it should be possible to maintain 25 + inches of vacuum at all times. + + + (26) _How long to retain the dish in the solids oven._ + + This varies with the products to be tested. The minimum time is ten + minutes and in the case of sweetened condensed milk, in order to get + absolute results, it is best to dry the samples an hour and a half. + + + (27) _How to cool the solids dish._ + + Transfer the dish from the oven to the cooler promptly, and keep the + same in the cooler for five minutes with the water circulating during + this time. + + + (28) _How to heat the solids dish._ + + Always weigh the solids dish with the dish cover upon the dish. Make + the weighings as rapidly as possible, as otherwise the sample is + quite likely to absorb moisture from the atmosphere. + + + (29) _How to calculate the percentage of total solids._ + + Divide the weight of the total solids by the weight of the sample + taken, and multiply the result by 100, which will give the percentage + of total solids in the sample. + + + (30) _Order of operations in testing evaporated milk for butter-fat + and total solids with Mojonnier tester._ + + In the following outline, the procedure described is that used in the + case of evaporated milk. The procedure in the case of other products + is much the same, but as described in directions, differences may + occur in the methods of weighing the samples; the size of the samples + to use; the quantity of water or the reagent to add; the method of + shaking, and the method of centrifuging. The outline presumes that + only one operator is doing the work. When speed is required, a helper + to the operator can materially shorten the time required. In that + case, the order of operations will need to be slightly modified. + + (1) See that respective dishes have been in vacuum oven at least five + minutes while ovens are heated with vacuum on. + + (2) Place respective dishes in cooling ovens, turn pump on, and set + bell for five minutes for solids and seven minutes for fat. + + (3) Weigh solids dish first--being careful to put cover on dish, and + record weight and number upon laboratory report. Put dish back into + cooling oven. + + (4) Weigh fat dish without cover. Record weight and number upon + laboratory report, and put fat dish back in cooling oven. + + (5) Fill one 5-gram and one 1-gram pipette with milk, and place upon + weighing cross. + + (6) Weigh above and note weight on laboratory report under “pipettes + plus milk” column. + + (7) Transfer milk in 5-gram pipette to extraction flask, and return + empty pipette to weighing cross. + + (8) Weigh again, and note weight in fat column under “pipettes.” + + (9) Put above weight in solids column of laboratory report, also + under heading of “pipettes plus milk.” + + (10) Transfer milk from one gram pipettes to the weighed solids dish, + and return pipette to weighing cross. + + (11) Place weighing cross upon balance, weigh, and record weight + under the heading “pipettes.” + + (12) Add equal volume of distilled water to solids dish, distribute + evenly, and place on solids hot plate. + + (13) When evaporation has taken place, put in solids oven. + + (14) Turn on vacuum and set bell for ten minutes. + + (15) At this point take extraction flasks with milk in and make first + extraction, centrifuge and pour ether into fat dish. + + (16) Make second extraction, same as 15. + + (17) During above period solids bell will ring and solids dish should + be transferred to cooling oven, and bell set for five minutes. + + (18) As soon as ether has evaporated, place dish in fat oven, turn + vacuum on, and set bell for five minutes. + + (19) When solids bell rings, weigh dish and record weight. + + (20) When fat test bell rings, transfer to cooling oven, and set bell + again for seven minutes. + + (21) Complete subtractions on laboratory report. + + (22) Weigh fat dish, turn pump off, and finish calculations. + + (23) From tests obtained, determine what material to add to + standardize batch. + + +=174. Testing evaporated, sweetened condensed, bulk condensed milk +ice-cream (mix or melted), for fat and total solids.=--The process is +outlined in the following steps: + + (1) Wash solids dishes with warm water and fat dishes with gasoline. + Dry with a towel and place into heated vacuum oven for five minutes, + with vacuum on. At the end of five minutes, put these dishes into + cooler and with pump still running, keep them there for five minutes + before weighing. Do not turn off motor until last dish is weighed out + of cooling chamber. + + (2) While dishes are being heated and cooled, wash pipettes with + water, alcohol and ether, and dry by applying vacuum at exhaust cock + upon tester. Always use clean and dry pipettes for each different + sample. Aim to clean pipettes as well as all glassware, immediately + after using. + + (3) It is very important to keep the extraction flasks clean. Wash + these with warm water immediately after extraction is finished. Wash + with washing powder and shot when necessary. + + (4) Keep solids dishes in cooler for at least five minutes, weigh + accurately to .0001, using the proper counterpoise. Weigh solids + dishes with cover on. Keep fat dishes in cooler for seven minutes + before being weighed. Fat dishes do not have cover. + + (5) Use pipettes as follows: Fill 5-gram pipettes up to 5 gram mark + for butter-fat and 1 gram pipette up to 1 gram mark for total solids. + If duplicates are to be run, fill two pipettes from the same sample. + As pipettes are filled, place lower end into cleaned and dry rubber + tubes which are pressed upon knobs at ends and center of weighing + cross. Either five or less samples for butter-fat or five or less for + total solids may be pipetted out. + + (6) Weigh the cross with the pipettes containing the milk on chemical + balance accurately to .0001 gram. Run milk from pipette into proper + flask, or 3 inch dish if making solids test. The pipettes may be + distinguished by the number upon each cross. Replace pipette and + weigh again. Difference in weight gives weight of sample. Repeat + until all samples are run into proper flasks, and into weighed solids + dishes if solids are determined along with the fat. + + For fat in sweetened condensed milk use a 5-gram sample. The 5-gram + pipette delivers approximately 5 grams between the 5 gram mark and + the base of the bowl of the pipette. + + Some operators prefer to mix 200 grams of sweetened condensed milk + with 200 grams of water, weighing these carefully upon a Harvard trip + scale sensitive to .1 gram. In this case, care must be exercised to + obtain the exact weight of both milk and water and to stir these + thoroughly with glass or metal rod before taking sample. A tall + tumbler, a one-pound bottle or a quart cup, make good containers in + which to make mixture. A 10-gram sample of this mixture is used. + This is best weighed out by using two 5-gram pipettes on weighing + cross. + + For total solids, weigh out ¹⁄₂ (.5000) to ³⁄₄ (.7500) gram of this + mixture. If the undiluted milk is used, take as nearly ¹⁄₄ (.2500) + gram as possible. + + For regular 8 per cent plain bulk condensed milk, use same size + samples and treat same as evaporated milk. For 12 per cent + superheated condensed milk, mix 100 grams milk with 300 grams water + upon Harvard trip scale. Weigh 10 gram sample of this mixture into + flask for fat, and a 2 gram sample into solids dish for solids. + Multiply percentages obtained by 4 for correct percentages, when a 1 + to 4 dilution is made. + + +=175. Fat determination.=--The following steps should be followed when +making the fat test. + + (1) Remove flask from holder and run 4 cubic centimeters water (one + charge on water burette) into each flask. Be careful not to add more. + Shake well until all of sample is mixed with water. This can be done + without inserting cork. + + For sweetened condensed milk, if not diluted with water, add 8 cubic + centimeters of hot water with a pipette. To get hot water, place fat + dish filled with distilled water upon solids plate. If sweetened milk + has been previously diluted with water and a 10 gram sample has been + used, it is not necessary to add water. It is very necessary to shake + the flasks containing the sweetened condensed milk very thoroughly + after the addition of each reagent. Sweetened condensed milk requires + more shaking than any other liquid milk product. + + (2) Before replacing flask into holder, add 1¹⁄₂ cubic centimeters C. + P. ammonia, one charge on burette. Shake well so that all of sample + is well mixed with ammonia. This can be done without inserting cork. + + (3) Add 10 cubic centimeters of 95 per cent alcohol. Insert cork, + twisting cork in firmly, using best quality corks only. Replace the + flask into flask holder. Shake thoroughly, and see that no milk + adheres to any part of flask undissolved. In case particles of milk + stick to side of flask, shake thoroughly until these are washed away. + It is of utmost importance to shake thoroughly at this point. + + (4) Add 25 cubic centimeters ethyl ether, insert corks and shake + vigorously, lengthwise of flask, with liquid in large bulb of flask, + and small bulb extended upward. Stop shaking at end of five seconds + until all liquid has run into large bulb and repeat vigorous shaking + for four five-second periods. + + (5) Add 25 cubic centimeters petroleum ether and shake in same way. + + (6) Place extraction flasks into centrifuge and whirl for thirty + turns at speed of about 600 revolutions a minute. Have centrifuge + balanced with small oil sample bottles furnished with tester. Double + time for sweetened condensed milk. + + (7) Place four 3¹⁄₂ inch dishes in line on shelf adjoining hot plate, + keeping them in order in which their weights were posted on record + sheet. Aim to have numbers on flasks correspond with number of dishes. + + (8) Pour ether extraction above dividing line into proper dishes + and slide dishes over onto hot plate which should be held at a + temperature of 135 deg. C, as indicated by thermometer inserted in + nickel plated mercury well. Be careful to pour off no solid matter. + Cover dishes with hood. + + (9) Repeat the extraction, shaking first to prevent formation of + precipitate, then adding successively 5 cubic centimeters of 95 per + cent alcohol, then 25 cubic centimeters ethyl ether and then 25 cubic + centimeters petroleum ether, and shake vigorously after the addition + of each of above three reagents for four five-second periods. + + (10) Whirl in centrifuge for thirty turns. + + (11) Move aluminum dishes back upon shelf adjoining hot plate, when + almost dry, and pour the second extraction into proper dishes. Never + pour extraction into hot dish. Remove dish from hot plate as soon as + ether is all evaporated. + + (12) When all of ether has evaporated, place dishes into vacuum + oven which should have a temperature of 135 deg. C. Keep them there + for five minutes after the vacuum gauge shows at least 22 inches of + vacuum. + + (13) Place dishes into cooler for seven minutes, with pump outfit + running. See that water is running through cooling plates. + + (14) Place counterpoise for dish and the approximate weight for fat + on right hand balance pan. + + (15) Transfer dish to left hand balance pan and weigh quickly to 0.10 + milligram (0.0001 gr.). + + (16) Weight of fat divided by weight of sample taken, multiplied by + 100 represents percentage butter-fat. + + +=176. Total solids determination.=--The steps in making the test are as +follows: + + (1) The temperature of the hot plate in the solids vacuum oven must + be 100 deg. C. The temperature of the outside solids plate must be + 170 deg. to 180 deg. C. + + (2) To weighed milk in solids dish, add about 1 cubic centimeter + water and distribute mixture evenly over bottom of dish, immediately + after weighing. For sweetened condensed milk, use hot water, or place + momentarily on hot plate and distribute evenly over dish by shaking + sidewise very carefully after cold water is added. + + (3) Place not more than two dishes at once upon hot plate, which must + be perfectly level. Allow all visible moisture to evaporate. During + the evaporation turn the dishes around with crucible tongs slowly so + as to produce an even boiling over the whole bottom surface of the + dishes. The dishes must be watched carefully during the evaporation. + This step should require not more than two minutes. The end point is + reached when bubbling and crackling ceases and sample shows first + trace of brown. Vigorous boiling without spattering and complete + evaporation are fundamentally essential. + + (4) Place dishes into vacuum oven which must be at 100 deg. C. and + turn on the vacuum. Heat for ten minutes. In the case of sweetened + condensed milk keep it for ninety minutes in vacuum oven, or heat for + twenty minutes and deduct 30 per cent from result. The gauge should + register not less than 22 inches of vacuum. If for any reason you + cannot obtain at least 22 inches of vacuum, then leave your dishes in + oven for twice the regular time. + + (5) Remove from oven and place into cooler. Allow dishes to cool for + five minutes. + + (6) Weigh dishes with covers on, being careful to weigh quickly and + very exactly. + + (7) Weight of dry solids divided by weight of milk taken, multiplied + by 100, represents percentage total solids. + + +=177. Testing butter.=--Both the fat and the moisture may be determined +by this test. The sample may be prepared in either of two ways: + + _Method I._ Remove about one-half pound butter from the different + parts of the churn or tub with a butter trier, and put this into + wide-mouthed bottle or Erlenmeyer flask fitted with rubber stopper + having a thermometer in the center of the stopper, and reaching down + into the mass of butter. Heat bottle in hot water until thermometer + reaches 40 deg. C. or 104 deg. F. If this temperature is not + exceeded, there is very little danger of the butter-fat spreading + rapidly from the curd. Shake vigorously. + + _Method II._ Another very satisfactory method of preparing butter for + sampling is to put butter as it comes from churn or tub into Mason + jar, beaker, glass tumbler, or wide-mouthed bottle, any of which may + be covered tightly to prevent evaporation. Allow these to stand in + warm room or in warm water until the butter is soft enough so that it + may be stirred thoroughly with table knife, spatula, or a mechanical + stirrer. At temperature of about 75 deg. to 80 deg. F. butter stirs + into a waxy form from which water or casein will not separate. In + this form, it is put into boat or flask to be weighed. + +Fat determination: + + (1) If sampling method I is used, measure (about) 1 gram into weighed + butter boat. Weigh quickly and insert boat into flask. If sampling + method II is used, put about 1 gram of the butter sample into weighed + boat, weigh quickly, and insert into extraction flask. + + (2) Remove flask from holder and add to extraction flask 9 cubic + centimeters hot water from aluminum dish placed on fat plate. Mark + 10-gram pipette up to 9 cubic centimeter and use this for measuring + hot water. Shake vigorously so as to mix butter thoroughly with water. + + (3) Before replacing flask into holder, add 1¹⁄₂. cubic centimeters + C. P. ammonia and shake thoroughly, making sure that butter is + thoroughly mixed with ammonia. + + (4) Add 10 cubic centimeters of 95 per cent alcohol. Insert cork. + Replace flask into flash holder. Shake flask thoroughly with cork + inserted. Use best quality corks only. + + (5) Cool flask by running cold water over lower end of extraction + flask, if flask is very hot. This is not ordinarily necessary. + + (6) Add 25 cubic centimeters ethyl ether. Insert corks, shake + vigorously until all butter is dissolved out of boat. Then add 25 + cubic centimeters petroleum ether and repeat operation. + + (7) Centrifuge flasks, turning handle thirty turns after centrifuge + has reached a speed of about 600 revolutions a minute. + + (8) Pour off extractions into proper weighed 3¹⁄₂ inch aluminum + dishes. Repeat above extraction, adding successively 5 cubic + centimeters of 95 per cent alcohol, then 25 cubic centimeters of + each ether. Excepting for very accurate work, a third extraction is + not necessary. The second extraction will remove all but .10 to .15 + per cent of the butter-fat. For factory control work this would be a + good margin of safety. + + (9) Evaporate off ether at 135 deg. C. on “fat plate,” and when all + of ether is off, dry fat in fat oven held at 135 deg. C. for five + minutes after the vacuum has reached at least 22 inches. + + (10) Cool, weigh, and calculate percentage butter-fat as in regular + fat test. + +To determine moisture in butter: + + If sampling method I is used, keep butter at 140 deg. F. and mix + thoroughly and while well mixed, weigh 1 gram into the solids dish + as quickly as possible to prevent evaporation. If second method of + sampling is used, weigh 1 gram of butter into the solids dish. Heat + on hot plate at 180 deg. C. until foaming ceases, and then place + in vacuum oven held at 100 deg. C. for seven minutes. Cool, weigh + and calculate percentage solids; 100 less this figure represents + percentage moisture. + + +=178. Testing fresh milk, skim-milk, whey, buttermilk for fat and total +solids.=--The fat test is made as follows: + + (1) Use the 10 gram pipettes for measuring out 10 grams of milk into + cleaned but not necessarily dried Mojonnier extraction flask. Use + only 10 gram pipettes furnished with tester and do not use 10 cubic + centimeter pipettes. The pipette is graduated to deliver 10 grams of + milk, after allowing all milk to run out and letting it drain for + fifteen seconds longer, then blowing gently to remove last drop. + The pipette must be perfectly clean and dry before being used. Wash + frequently with sulfuric acid, water, alcohol, and ether to insure + having a clean pipette. + + (2) Make extractions exactly as in test for butter-fat in condensed + milk, excepting that no water need be added, and in second extraction + only 15 cubic centimeters of each ether need be used. + + (3) Percentage butter-fat is obtained by multiplying the weight of + the extracted butter-fat by 10. + + (4) If any of these products have soured badly, double the quantity + of ammonia in the regular extraction and shake until all particles + are dissolved. + +Total solids determination: + + Determining total solids as in evaporated milk, excepting that a + 2-gram sample is weighed out, and no water need be added to spread + the milk over the bottom of the dish. + + +=179. Testing powdered milk, cocoa, malted milk and milk chocolate for +fat and total solids.=-- + + Mix the sample thoroughly, making sure that it is sufficiently + pulverized, and representative of the entire lot to be tested. In the + case of milk chocolate, pulverize the sample very thoroughly, in a + close grained mortar. Transfer the pulverized sample promptly to a + sealed jar. Mix before removing portions for testing. + +Butter-fat determination: + + (1) Weigh out rapidly, to prevent absorption of moisture from the + air, about 1 gram of milk powder into butter boat. In case of malted + milk, milk chocolate and cocoa, weigh out a 0.5 gram sample. + + (2) Add 8.5 cubic centimeters of hot water to flask. Insert cork. + Heat flask in water boat, and shake thoroughly until the sample is + well mixed. + + (3) Add 1.5 cubic centimeters (one charge) ammonia, and shake + thoroughly. + + (4) Add 10 cubic centimeters of 95 per cent alcohol. Shake + thoroughly. Cool the flask, if necessary. + + (5) Continue the extraction exactly as directed under the butter-fat + determination, paragraphs 4, 5, 6, and 7, inclusive. + +Total solids determination: + + Use .3000 gram sample. Add 2 cubic centimeters distilled water to the + sample in this dish. Otherwise continue the determination exactly as + directed under total solids determination in cheese. + + +=180. Testing cream for fat and total solids.=-- + + Mix sample thoroughly in the container. If the cream has been + homogenized, it can be weighed with the weighing pipettes as + described under 5, page 230 of these directions. If the cream is + churned or lumpy it has to be heated until the fat is all just barely + melted, and the entire mixture is uniform. Cream is a product that + is subject to many variations in composition, degree of acidity, and + physical condition. For these reasons, the operator needs to exercise + the best judgment possible. The method of operation may require, at + times, slight modification, depending on the condition of the sample. + +Butter-fat determination: + + (1) For cream testing under 15 per cent butter-fat, take about a 2 + gram sample, using 2-gram pipette. For cream testing over 15 per + cent butter-fat take a 1-gram sample. If practicable, weigh out of + pipette as described under 5, page 230. Otherwise weigh the sample in + the butter boat, or directly into the extraction flasks, which were + previously weighed. + + (2) Remove flask from the holder and add enough water to make a total + of 10 cubic centimeters. Insert cork and mix thoroughly. + + (3) Before replacing flask in holder, add 1.5 cubic centimeters (one + charge) of ammonia. If the cream is sour add 3 cubic centimeters of + ammonia. This is very important. + + (4) From this point to the end of the test, continue as stated on + page 231, beginning at paragraph 2 to paragraph 16, inclusive. At + the end of the second extraction it may be necessary to add quite a + little more alcohol, in order to bring the dividing line up to the + required height. + +Total solids determination: + + Use a 1.0 gram sample. Add 1 cubic centimeter distilled water to the + sample in the dish. Otherwise proceed exactly as directed in sections + 3 to 7 of page 233. + + +=181. List of precautions to observe in operating Mojonnier tester.=-- + + (1) Before the reagents are put into the cans, be sure that the cans + are thoroughly cleaned by washing all parts, first with warm water, + then alcohol and then ether. Every third or fourth time cans are + filled, empty out last portion of reagents, and use for cleaning + purposes. + + (2) The bottoms of all dishes should be kept as flat as possible. Any + bulging may be worked out by resting dishes upon marble plate in + front of balance, rubbing entire bottom surface with thumbs. Operator + should observe this every time dishes are cleaned. This is very + important. + + (3) The calcium chloride in the coolers should be changed every three + or four weeks. The same calcium chloride may be used over and over by + drying the used calcium chloride in tin dishes placed upon hot plate + held at 135 deg. C. for at least five hours. + + (4) The bottles should be whirled in the centrifuge until the ether + extraction is perfectly clear. About thirty turns at a normal speed + are to be recommended. For sweetened condensed milk this time must be + doubled. + + (5) Be sure to keep extraction flasks perfectly clean. Wash often + with sulfuric acid and washing powder, if necessary. If particles + cling to the sides put in small shot, washing powder and hot water, + and shake thoroughly. + + (6) Keep temperature regulated as nearly to standard temperature as + possible. + + (7) Never pour off extraction into a hot dish. Remove dish from plate + before second extraction is run into dish. + + (8) Be careful to pour off ether into dishes slowly at first and + gradually increase stream until full stream is running. + + (9) In using weighing pipettes, make sure that neck of flask is free + from water when pipette is inserted. + + (10) Always use clean and dried pipettes. + + (11) If the samples for solids have to stand for any length of time, + add the water just as soon as they are measured out, otherwise + there is a tendency to dry and a good mixture with water cannot be + obtained. Keep dishes upon marble plate beside the balance, and not + on hot plate support. + + (12) Redistill ethyl ether and petroleum ether, unless they are known + to be pure. This is unnecessary if these are bought from a reliable + firm. + + (13) Make sure that water is always running through cooling plate. + Watch pipe back of cooler. If tester is located in cold room in + winter, add a gallon of denatured alcohol to tank to prevent freezing. + + (14) Always aim to weigh empty dishes just before you are ready to + use them. It is not advisable to weigh them a long time before they + are used. + + (15) It is fundamentally important to see that weights are read and + posted rightly. Operator should-keep his weights in systematic order + upon balance pan. When a reading is taken, it should be checked at + least three times. Learn to make weighing absolutely correct. One + figure misread may cost a month’s salary. + + (16) Every operator should from time to time have a sample checked by + a thoroughly reliable laboratory. Mojonnier Bros. Company, Chicago, + Illinois, maintain such a laboratory exclusively for this purpose. + Charges very moderate. + + If results on fat are high as compared with check results, the cause + may be one of the following: + + (a) Not keeping bottoms of dishes flat. + + (b) Improper shaking and centrifuging shown by non-fatty residue in + dish. + + (c) Improper reagents (if in doubt run test upon reagents + substituting water for milk). + + (d) Temperature in fat oven too low. + + (e) Dirt has gotten into dish after ether was poured into it. + + (f) Improper reading or posting of weights. Weights have lost weight + from use. + + If results on fat are low as compared with check results, the cause + may be one of the following: + + (a) Leaky corks. Use best corks obtainable. + + (b) Insufficient shaking. + + (c) Adding too much water. + + (d) Having dividing line too low, so that too much ether is left + behind. If such is the case, add more alcohol to bring line to the + proper height, before pouring off, or make a third extraction. + + (e) Too high temperature in vacuum oven. + + (f) Not having water running through cooler. Tank must be kept filled. + + (g) Improper reading or posting of weights. + + If results on total solids are too high, as compared to check results + the cause may be one of the following: + + (1) Bottoms of dishes are not kept flat. + + (2) Evaporation upon solids plate has not been carried far enough. Be + sure to manipulate dish so that vigorous boiling takes place upon the + entire surface of the bottom of the dish. Do not remove dish until + all visible moisture is off or until first trace of brown coloration + appears. + + (3) Improper reading or recording of weights. Weights have lost + weight from use. + + (4) Dirt has fallen into dish after sample has been weighed into it. + + (5) Temperature in vacuum oven is too low. + + (6) Vacuum is not up to standard. + + If results on total solids are too low, the cause may be one of the + following: + + (1) Sample is browned too much upon outside hot plate. + + (2) Temperature in vacuum oven is above 105 deg. C. + + (3) Milk spattered from dish. This will not happen if temperature is + kept at 180 deg. C. + + (4) Improper reading or recording of weights. + + (5) Water is not running through cooler. + + +MOJONNIER OVER-RUN TESTER + +A simple test for determining the percentage of swell or over-run has +been devised by Mojonnier Brothers. This can be used in connection with +the freezing to obtain a uniform over-run on each freezer of ice-cream. +The tester is shown in Fig. 76. + +The over-run tester should be placed in the freezer-room between two +freezers, as it is designed to work both sides. The base or pedestal +should be levelled carefully as follows: Place level on surface just +over the pedestal cabinet. This should be levelled in both ways. When +pedestal is levelled, fasten securely with lag screws or bolts to +floor, using same method employed in fastening base of freezers to +floor. + +In large freezer-rooms when a girl makes over-run tests and records the +over-run and advises the freezer man when to draw, one over-run tester +for each six freezers will suffice. When the freezer man makes his +own tests and records, one over-run tester will suffice for each four +freezers; that is, two freezers on either side. + + +=182. Adjusting cups for mix.=--The cup should be adjusted for every +batch, except in some ice-cream plants, where the butter-fat and +total solids are carefully standardized. In such cases, after the cup +has been adjusted, it will require very little, if any, adjusting +thereafter. For instance, if the mix is standardized to 8 per cent +butterfat and 33 per cent total solids and is kept at this standard by +careful testing, no adjustments need be made. The threads of the cup +are slightly greased with vaseline before being shipped. They should be +slightly greased occasionally, to facilitate free action. + +[Illustration: FIG. 76.--Mojonnier over-run tester.] + +The following directions should be followed: + +See that the telescopic base of over-run cup is unscrewed as far as is +necessary to hold 500 gram mix (counterpoised by the 0 per cent weight. +This will be a little less than one pint). Place empty cup in suspended +cup holder. Fill dipper with the finished mix from hopper, or pipe +line, and pour in the mix until dial indicator points to 0 per cent. +The mix should contain all ingredients, namely, sugar, gelatine, and +the like. + +Remove the cup of mix from the scale, place the slotted base on the +metal cleat underneath the weighing frame. Adjust this telescopic base +by turning cup around so that the top of mix comes exactly even with +the top of the cup. Carefully lock the base of the cup in position by +means of the knurled locking ring. + +After the cup is adjusted, empty the mix back into the hopper over the +freezer, and rinse out the cup in a pail or five-gallon can of warm +water, making ready for the over-run determinations. There is now a +fixed relation between the capacity, and the weight of the cup and the +markings on the scale dial. + + +=183. Actual operation.=--A heaping cup of frozen ice-cream should +be drawn from the freezer, scraping excess off with the broad plated +knife, to an even level. Cup is placed in suspended weighing frame. The +dial indicator will immediately show the percentage of over-run. If +it points to 60, it indicates 60 per cent over-run; if to 90, 90 per +cent and so on. Two operators may use the same over-run tester at the +same time if desired, one working from either side. Repeated use of the +tester will enable the operator to handle the work with considerable +dexterity and speed. + + +=184. Controlling the over-run.=--While there is no set rule that can +be followed regarding the control of over-run, the following may offer +some suggestions to operators: + +There are two approved methods for operating the Mojonnier ice-cream +over-run tester. + +1. By a special tester, either a girl or a man whose sole duties are +to test the frozen ice-cream carefully, and notify the freezer man when +to draw the ice-cream from the freezers, that is, after it has reached +the desired over-run. In this method, one operator may run six freezers +for each over-run tester. + +2. When the freezer man makes his own tests just before drawing the +ice-cream from the freezers. In order properly to control the over-run, +there should be one tester for each four freezers. + +The first method applies particularly when from one to eight freezers +are used. The second method applies to large plants having more than +eight freezers in use, and where there is difficulty in procuring +adequate help, or when it becomes necessary to change help frequently. + + _First operation:_ When starting to freeze a new batch, see that + over-run cup is adjusted as described. + + _Second operation:_ Draw exactly five gallons of cream into the + hopper above freezers when using a ten-gallon freezer. (If larger + freezers are used, draw a volume into the hopper equal to one-half + rated capacity of freezer.) It is well to graduate and mark very + plainly the one-half capacity upon the hopper of the freezer. + + _Third operation:_ Run mix into the freezers as usual, filling all + four freezers, while the freezers are running. + + _Fourth operation:_ Turn on the brine and continue whipping. + + _Fifth operation:_ The brine temperature and the brine pressure + should be such that about 100 per cent over-run can be obtained with + the brine turned off, and by turning on the brine again, will result + in the over-run going down too quickly. If turning on the brine after + whipping does not reduce the over-run, it is an indication of poor + brine temperature. In that case, shutting down the machine for a + short time is advisable, in order to get the brine temperature down + to a point where freezing may be done efficiently, and the yield or + over-run kept under proper control. + + It is well to regulate the proper pressure according to the brine + temperature until the desirable over-run is obtained. There is a + fixed relation between these two factors, and by using the over-run + test as a guide, it is possible to adjust the pressure to the + temperature necessary to obtain the best over-run. + + Brine valves on each freezer should be kept in good condition so + that when they are turned off, there is no flow of brine through + the freezer. A leaky valve may cause the over-run to refuse to go + up, due to the low temperature of the batch, thus preventing proper + whipping. Whip with the brine on until the ice-cream is quite stiff. + At this point, take test for over-run. If a satisfactory over-run + is procured, turn on brine and draw off batch. If a satisfactory + over-run has not yet been obtained, turn on the brine and continue + whipping until by repeated test, the proper over-run is obtained. + After the freezer is emptied, this operation is repeated in the same + way. + + Many operators make it a point to draw off ice-cream when over-run + shows between 90 and 100. Ice-cream with over-run of more than 110 + per cent is usually not a satisfactory commercial product. + + _Sixth:_ Record under the proper freezer number on the freezer-room + blank, the final over-run test indicated when the cream is drawn. + Do not record any but the final result. This will form a valuable + check on the volume of ice-cream as recorded in the hardening-room. + It is possible in this way for the manager of the plant to obtain an + accurate idea of how careful the over-run has been controlled. + + + _Operating under the second method, or when a girl makes the over-run + tests._ + + Under this method, the helper in the freezer-room should not draw off + the ice-cream until it has been carefully tested and controlled. One + girl can test and control the over-run of ice-cream from six freezers + with one over-run tester, having three freezers on each side. She + can keep close watch of the frozen cream through the peep hole in + top of the freezer. As soon as the cream seems to be of the proper + consistency, a test of the over-run should be made. + + + _Principal causes of variation in over-run:_ + + The following factors influence the over-run: + (1) Milk solids in the mix + (2) Butter-fat in the mix + (3) Speed of freezers + (4) Proper ratio between solids + not fat and butter-fat + (5) Age of mix + (6) Acidity of mix + (7) Brine pressure + (8) Brine temperature + (9) Time of freezing + (10) Amount of mix drawn into freezer + (11) Blades of dasher dull or worn + (12) Slipping of belt + (13) Leaky brine valves + (14) Type of freezers + +TABLE XIII + +Summary of Methods of Making Fat Tests and Total Solids Tests with the +Mojonnier Tester + + -----------+--------------+---------+---------+ + | | | | + | | | | + | | | | + | | | | + | | | | + | | |_Size of | + _Product |_How to |_How to |sample to+ + to be |prepare |weigh fat|take for | + tested_ |samples_ |sample_ |fat test_| + -----------+--------------+---------+---------+ + _Fresh |Mix |Measure |10 grams | + milk_ |thoroughly |with 10 | | + | |gram | | + | |pipette. | | + | |Drain | | + | |pipette | | + | |15 | | + | |seconds | | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Skim- |Mix | „ | „ | + milk_ |thoroughly. | | | + |Get | | | + |representative| | | + |sample | | | + -----------+--------------+---------+---------+ + _Whey_ | „ | „ | „ | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Butter- |Mix thoroughly| „ | „ | + milk_ | | | | + | | | | + -----------+--------------+---------+---------+ + _Evaporated|Shake in can |Use cross|Weigh | + milk_ |very |and 5 |about | + |thoroughly| |gram |5 grams | + | |pipette | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Bulk un- |Mix very | „ | „ | + sweetened |thoroughly. | | | + condensed |Get | | | + milk_ |representative| | | + |sample | | | + -----------+--------------+---------+---------+ + _Bulk, | „ |Use cross|About 3 | + extra heavy| |and one 5|grams | + unsweetened| |gram | | + condensed | |pipette | | + milk_ | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Sweetened |Proceed |Use cross|About | + condensed |without |and 5 |5 grams | + milk_ |diluting. |gram | | + |Mix thoroughly|sample | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Ice-cream |Mix |Use cross| „ | + mix_ |thoroughly. |and 5 | | + |Heat slightly |gram | | + |if necessary |pipette | | + |to melt fat |and weigh| | + | |rapidly | | + | |or weigh | | + | |directly | | + | |into | | + | |flask | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Cream |Mix |Use weigh|About 2 | + testing |thoroughly. |cross |grams | + less than |Heat slightly |with 2 | | + 25% b. f._ |if necessary |gram | | + |to melt fat |pipette. | | + | |If | | + | |necessary| | + | |use boat | | + | |or weigh | | + | |directly | | + | |into | | + | |flask | | + | | | | + -----------+--------------+---------+---------+ + _Cream | „ | „ |About | + testing | | |1 gram | + more than | | | | + 25% b. f._ | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Malted |Mix |Use |.5 gram | + Milk_ |thoroughly. |butter | | + |Get |boat, or | | + |representative|weigh | | + |sample |directly | | + | |into | | + | |flask | | + | | | | + -----------+--------------+---------+---------+ + _Milk |Pulverize in | „ | „ | + chocolate_ |close grained | | | + |mortar. | | | + ||Transfer to | | | + |sealed jar | | | + -----------+--------------+---------+---------+ + _Cocoa_ |Mix | „ | „ | + |thoroughly. | | | + |Get | | | + |representative| | | + |sample | | | + -----------+--------------+---------+---------+ + _Cheese_ |Pulverize in | „ |1.0 gram | + |close grained | | | + |mortar. | | | + |Transfer to | | | + |sealed jar | | | + -----------+--------------+---------+---------+ + _Butter_ |See detailed |Use | „ | + |directions |butter | | + | |boat | | + | | | | + | | | | + | | | | + | | | | + -----------+--------------+---------+---------+ + _Skimmed- |Pulverize in |Use |About 1 | + milk |close grained |butter |gram | + powder_ |mortar. |boat or | | + |Transfer to |weigh | | + |sealed jar |directly | | + | |into | | + | |flask | | + | | | | + -----------+--------------+---------+---------+ + _Whole-milk| „ | „ | „ | + powder_ | | | | + | | | | + -----------+--------------+---------+---------+ + + -----------+-------------------------------------------------------+ + | | + | | + | | + | | + | | + | REAGENTS TO ADD, AND HOW TO SHAKE, FIRST EXTRACTION | + _Product +-----------+----------+----------+----------+----------+ + to be | | | |_Ethyl |_Petroleum| + tested_ |_Water_ |_Ammonia_ |_Alcohol_ |ether_ |ether_ | + -----------+-----------+----------+----------+----------+----------+ + _Fresh |No water |1.5 c.c. |10 c.c. |Add 25 |Add 25 | + milk_ | |Shake |Shake half|c.c. |c.c. | + | |thoroughly|minute |Shake for |Shake for | + | | | |one minute|one minute| + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Skim- | „ |1.5 c.c. |Shake very| „ | „ | + milk_ | | |thoroughly| | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Whey_ | „ |1.5 c.c. | „ | „ | „ | + | |Use more | | | | + | |if whey is| | | | + | |acid. | | | | + | |Shake | | | | + | |thoroughly| | | | + -----------+-----------+----------+----------+----------+----------+ + _Butter- | „ |1.5 c.c. | „ | „ | „ | + milk_ | |Shake | | | | + | |thoroughly| | | | + -----------+-----------+----------+----------+----------+----------+ + _Evaporated|Use 4 c.c. | „ | „ | „ | „ | + milk_ |Shake | | | | | + |thoroughly | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Bulk un- | „ | „ | „ | „ | „ | + sweetened | | | | | | + condensed | | | | | | + milk_ | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Bulk, |7 c.c. |1.5 c.c. |10 c.c. | „ | „ | + extra heavy|Shake very |Shake very|Shake one | | | + unsweetened|thoroughly.|thoroughly|minute | | | + condensed |Hot water | | | | | + milk_ |preferred | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Sweetened |8 c.c. hot |1.5 c.c. | „ | „ | „ | + condensed |water. |Shake | | | | + milk_ |Shake until|thoroughly| | | | + |thoroughly | | | | | + |mixed | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Ice-cream |6 c.c. | „ | „ | „ | „ | + mix_ |Shake | | | | | + |thoroughly | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Cream |6 c.c. |1.5 c.c. |10 c.c. |Add 25 |Add 25 | + testing |Shake |Use 3.0 |Shake half|c.c. |c.c. | + less than |thoroughly |c.c. if |minute |Shake for |Shake for | + 25% b. f._ | |cream is | |one minute|one minute| + | |acid. | | | | + | |Shake | | | | + | |thoroughly| | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Cream |8 c.c. | „ | „ | „ | „ | + testing |Shake | | | | | + more than |thoroughly | | | | | + 25% b. f._ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Malted |10 c.c. |1.5 c.c. | „ | „ | „ | + Milk_ |hot. |Shake very| | | | + |Shake |thoroughly| | | | + |thoroughly | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Milk | „ | „ | „ | „ | „ | + chocolate_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Cocoa_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Cheese_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Butter_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Skimmed- |8.5 c.c. |1.5 c.c. |10 c.c. | „ | „ | + milk |Hot water. |Shake |Shake one | | | + powder_ |Shake |thoroughly|minute | | | + |thoroughly | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + _Whole-milk| „ | „ | „ | „ | „ | + powder_ | | | | | | + | | | | | | + -----------+-----------+----------+----------+----------+----------+ + + -----------+----------+----------------------------+----------+ + | |SHAKE—SECOND EXTRACTION—Use | | + | |no ammonia, add water after | | + | |centrifuging as indicated. A| | + | |few drops of phenolphthalein| | + | |indicator will make a much | | + | |more distinct dividing line.| | + _Product |How long +---------+-------+----------+How long | + to be |to | |_Ethyl |_Petroleum|to | + tested_ |centrifuge|_Alcohol_|ether_ |ether_ |centrifuge| + -----------+----------+---------+-------+----------+----------+ + _Fresh |30 turns |5 c.c. |15 c.c.|15 c.c. |30 turns | + milk_ | |Shake 20 |Shake |Shake 20 | | + | |sec. |20 sec.|sec. | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Skim- | „ | „ | „ | „ | „ | + milk_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Whey_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Butter- | „ | „ | „ | „ | „ | + milk_ | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Evaporated| „ | „ |25 c.c.|25 c.c. | „ | + milk_ | | |Shake |Shake | | + | | |20 sec.|20 sec. | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Bulk un- | „ | „ | „ | „ | „ | + sweetened | | | | | | + condensed | | | | | | + milk_ | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Bulk, | „ | „ | „ | „ | „ | + extra heavy| | | | | | + unsweetened| | | | | | + condensed | | | | | | + milk_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Sweetened |60 turns | „ | „ | „ |60 turns | + condensed | | | | | | + milk_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Ice-cream |30 turns | „ | „ | „ |30 turns | + mix_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Cream |30 turns |5 c.c. |25 c.c.|25 c.c. |30 turns | + testing | |Shake 20 |Shake |Shake 20 | | + less than | |sec. |20 sec.|sec. | | + 25% b. f._ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Cream | „ | „ | „ | „ | „ | + testing | | | | | | + more than | | | | | | + 25% b. f._ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Malted | „ | „ | „ | „ | „ | + Milk_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Milk | „ | „ | „ | „ | „ | + chocolate_ | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Cocoa_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Cheese_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Butter_ | „ | „ | „ | „ | „ | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Skimmed- | „ | „ |15 c.c.|15 c.c. | „ | + milk | | |Shake |Shake 20 | | + powder_ | | |20 sec.|sec.| | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + | | | | | | + -----------+----------+---------+-------+----------+----------+ + _Whole-milk| „ | „ |25 c.c.|25 c.c. | „ | + powder_ | | |Shake |Shake 20 | | + | | |20 sec.|sec. | | + -----------+----------+---------+-------+----------+----------+ + + -----------+---------+--------++---------+--------+---------+--------- + | | || | | | + | | || | | | + | | || | | | + | |How long|| | | |How long + | |to keep || |Size of |Amount |to keep + |How to |sample ||How to |sample |of water |sample + _Product |raise |in ||weigh |to take |to add to|in + to be |dividing |oven and||solid |for |sample |oven and + tested_ |line |cooler ||sample |solids |in dish |cooler + -----------+---------+--------++---------+--------+---------+--------- + _Fresh |If |5 min. ||Use cross|2 grams |none |10 min. + milk_ |necessary|in oven ||and 2 | | |in oven + |to raise |at ||gram | | |at + |dividing |135° C. ||pipette, | | |100° C. + |line, add|7 min. ||or | | |5 min. + |the |in ||pipette | | |in + |necessary|cooler ||about 2 | | |cooler + |distilled|at room ||grams | | |at room + |water |temp. ||directly | | |temp. + |just | ||into dish| | | + |before | ||upon | | | + |pouring | ||balance | | | + |off | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Skim- | „ | „ ++ „ | „ | „ | „ + milk_ | | || | | | + | | || | | | + | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Whey_ | „ | „ || „ | „ | „ | „ + | | || | | | + | | || | | | + | | || | | | + | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Butter- | „ | „ || „ | „ | „ | „ + milk_ | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Evaporated| „ | „ ||Use cross|1 gram |1 c.c. | „ + milk_ | | ||and 1 | | | + | | ||gram | | | + | | ||pipette, | | | + | | ||or | | | + | | ||pipette | | | + | | ||about 1 | | | + | | ||gram | | | + | | ||directly | | | + | | ||into dish| | | + | | ||upon | | | + | | ||balance | | | + -----------+---------+--------++---------+--------+---------+--------- + _Bulk un- | „ | „ || „ | „ | „ | „ + sweetened | | || | | | + condensed | | || | | | + milk_ | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Bulk, | „ | „ ||Use cross|50 gram |2 c.c. | „ + extra heavy| | ||and 5 | | | + unsweetened| | ||gram | | | + condensed | | ||pipette, | | | + milk_ | | ||or | | | + | | ||pipette | | | + | | ||about 5 | | | + | | ||grams | | | + | | ||directly | | | + | | ||into dish| | | + | | ||upon | | | + | | ||balance | | | + -----------+---------+--------++---------+--------+---------+--------- + _Sweetened | „ | „ ||Use cross|.25 gram| „ |90 min. + condensed | | ||and | | |in oven + milk_ | | ||pipette, | | |at 100° + | | ||or | | |C., or 20 + | | ||pipette | | |min. and + | | ||about | | |deduct + | | ||quarter | | |.30% from + | | ||gram | | |total. + | | ||directly | | |5 min. in + | | ||into dish| | |cooler at + | | ||upon | | |room + | | ||balance | | |temp. + -----------+---------+--------++---------+--------+---------+--------- + _Ice-cream | „ | „ ||Use cross|1 gram |1 c.c. |10 min. + mix_ | | ||and 1 | | |in oven + | | ||gram | | |at 100° + | | ||pipette, | | |C. + | | ||or | | |5 min. in + | | ||pipette | | |cooler at + | | ||about 1 | | |room + | | ||gram | | |temp. + | | ||directly | | | + | | ||into dish| | | + | | ||upon | | | + | | ||balance | | | + -----------+---------+--------++---------+--------+---------+--------- + _Cream |If |5 min. ||Use cross|1 gram |1 c.c. |10 min. + testing |necessary|in oven ||and 1 | | |in oven + less than |to raise |at 135° ||gram | | |at 100° + 25% b. f._ |dividing |C. ||pipette, | | |C. + |line, add|7 min. ||or | | |5 min. in + |the |in ||pipette | | |cooler at + |necessary|cooler ||about 1 | | |room + |distilled|at room ||gram | | |temp. + |water |temp. ||directly | | | + |just | ||into dish| | | + |before | ||upon | | | + |pouring | ||balance | | | + |off | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Cream | „ | „ ||Use cross|.50 gram| „ | „ + testing | | ||and 1 | | | + more than | | ||gram | | | + 25% b. f._ | | ||pipette, | | | + | | ||or | | | + | | ||pipette | | | + | | ||about | | | + | | ||half gram| | | + | | ||directly | | | + | | ||into dish| | | + | | ||upon | | | + | | ||balance | | | + -----------+---------+--------++---------+--------+---------+--------- + _Malted | „ | „ ||Weigh |.30 gram|2 c.c. |20 min. + Milk_ | | ||sample | | |in oven + | | ||directly | | |at 100° + | | ||into dish| | |C. + | | ||upon | | |5 min. in + | | ||balance | | |cooler at + | | || | | |room + | | || | | |temp. + -----------+---------+--------++---------+--------+---------+--------- + _Milk | „ | „ || „ | „ | „ | „ + chocolate_ | | || | | | + | | || | | | + | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Cocoa_ | „ | „ || „ | „ | „ | „ + | | || | | | + | | || | | | + | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Cheese_ | „ | „ || „ |.50 gram|1.5 c.c. | „ + | | || | | | + | | || | | | + | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + _Butter_ | „ | „ || „ |1 gram |none |7 min. in + | | || | | |oven at + | | || | | |100° C. + | | || | | |5 min. in + | | || | | |cooler at + | | || | | |room + | | || | | |temp. + -----------+---------+--------++---------+--------+---------+--------- + _Skimmed- | „ | „ || „ |.30 gram|3 c.c. |10 min. + milk | | || | | |in oven + powder_ | | || | | |at 100° + | | || | | |C. + | | || | | |5 min. in + | | || | | |cooler at + | | || | | |room + | | || | | |temp. + -----------+---------+--------++---------+--------+---------+--------- + _Whole-milk| „ | „ || „ | „ | „ | „ + powder_ | | || | | | + | | || | | | + -----------+---------+--------++---------+--------+---------+--------- + + +=185. Savings and economies.=--By using the Mojonnier over-run tester +intelligently, the operator can insure the management an even uniform +product from day to day, at an economical cost. Many plants have +increased their over-run test, and at the same time turned out a more +satisfactory product. + +Success depends on how carefully and consistently the tester is +operated. The operator can soon make himself very valuable to the +management of the ice-cream factory. The tester removes guess-work from +the freezer-room practice and places it on a scientific basis. + + + + +CHAPTER XV + +_MARKETING AND BUSINESS MANAGEMENT_ + + +The question of a market for the product is most vital. If the +ice-cream is manufactured and a market cannot be found, the business is +a failure. This is more especially true with ice-cream than the other +dairy products since practically no middle-men or commission merchants +will handle it. Another vital question is the cost of marketing; if too +high, the apparent profits of manufacture may be required to meet this +cost and again the business is a failure. + + +=186. Demand for ice-cream.=--The growing demand for ice-cream is +indicated by the figures in Chapter XVII. The question might naturally +be asked why this demand is increasing. There are three possible +answers to this. The consumer in the past regarded ice-cream as a +delicacy to be indulged in only on special occasions. Now the food +value is recognized and it is being consumed in large quantities as a +food. + +In the past it was often difficult to secure ice-cream in a +satisfactory condition. This was due to a poor delivery system and a +lack of knowledge regarding the handling. At present, however, these +difficulties have been overcome largely. + +In the hot summer weather, persons like to eat or drink some substance +which is pleasing to the taste and at the same time has a cooling +effect on the body; and no dish can replace ice-cream for this purpose. + +This condition, namely, the demand for ice-cream in summer and the +lack of it in winter, is a matter of great concern to the manufacturer. +It gives him an unequal distribution of his business throughout the +year. This is a decided disadvantage for several reasons: 1. It is +hard to secure satisfactory help for a short period of time; 2. It is +difficult to obtain milk products in sufficient quantities only for the +hot weather; 3. It requires a large investment in equipment which is +used only a part of the year. The usual result is that the ice-cream +manufacturer is forced to pay a higher price for his milk products, if +he takes them only during the summer. On the other hand, if the milk +products are purchased by the year, a profit is realized during the +period of large demand and the balance of the year they are handled in +some other way with a view of breaking even or reducing the loss as +much as possible. In order to be sure of help for the rush season, it +is usually necessary to keep at least a part of the necessary summer +force during the slack season. They can be employed in cleaning the +plant and making the necessary repairs for the next rush season. +The creating of a market for ice-cream in the winter is an unsolved +problem. It has been overcome partially in some plants by making fancy +or special ice-creams. They usually require more labor and hence sell +at a higher price and are in demand for various society functions which +are more common in the winter. + + +=187. Food value of ice-cream.=--Up to the present no investigations +have been made dealing with the food value or healthfulness of +ice-cream. It would seem that the previous statements about the food +value of milk, cream, and butter would apply to ice-cream. Miss +Rose[50] gives the following summary regarding the value of milk as a +food: + +[50] Rose, Flora, “Milk a cheap food,” Cornell Reading Course, Lesson +III, 1917. + +“With all the evidence in, no food bears the investigation of nutritive +properties better than does milk. It is impossible to escape the +conviction that not only is it a cheap food, but it is one whose value +can hardly be estimated in terms of dollars and cents. It has been +pointed out that: + +1. Although milk is not the cheapest source of energy that can be +bought, it is nevertheless an important source of energy, and the +energy-yielding substances, the protein, the milk-sugar, and the +milk-fat, have special value. + +2. Milk is a cheap source of protein because the protein that it +contains is of a kind particularly valuable for building tissue. + +3. Ordinarily milk is the cheapest and most valuable source of lime, +unless it is discovered that lime in water can take the place of lime +in milk. + +4. Milk is a valuable and cheap source of phosphorus. + +5. Milk is deficient in iron, but the iron that it contains is +particularly well utilized by the body. + +6. Milk is the most important of the three foods, milk, eggs, and +meat, which are the chief sources of a factor in foods that is soluble +in fat, that is essential to growth and health, and that is called +“fat-soluble A.” + +7. Milk is one of the most important sources of a factor in foods that +is soluble in water, that is essential to growth and health, and that +is called “water-soluble B.” + +Jerome Alexander[51] shows the effect of gelatine on the digestibility +of milk products. The chief constituents of ice-cream are crystalloids; +that is, substances that can form crystals, whereas gelatine is a most +characteristic member of the group of non-crystallizing substances +known as colloids. Research has shown that colloids or hydrosols as +they are sometimes known may be divided into two classes or groups; +depending on the way they behave when they dry out. The first group +which includes those that can be redissolved after being dried, such as +gelatine, are called the reversible colloids or reversible hydrosols. +The second group, which includes those that cannot be redissolved +after drying, such as pure colloidal metals, oxides and the like, +are known as irreversible colloids or irreversible hydrosols. The +reversible colloids are not sensitive but will stand the addition of +most substances without coagulation. In the case of ice-cream, the +addition of gelatine tends to prevent the coagulation of casein, which +is an irreversible colloid and the important proteid or nitrogenous +constituent of cows’ milk. For this reason gelatine renders ice-cream +more readily digestible and therefore more healthful; as is well known, +milk is immediately coagulated on coming in contact with the acid +juices of the stomach. But in the presence of gelatine the casein is +either prevented from coagulating or if it does coagulate the clots or +curds are so fine grained that they dissolve very easily in the process +of digestion. + +[51] Alexander, Jerome, “The beneficial effect of gelatine upon the +digestion of milk and cream,” “Ice-cream Trade Journal,” Vol. 5, No. 2. + +The composition of ice-cream varies with the materials used. The +flavoring material affects the percentage composition. The following +are fair examples of the chemical composition of commercial vanilla +ice-cream containing different percentages of fat: + +TABLE XIV + +Composition of Ice-cream Containing Different Percentage of Fat + + _Sample _Carbo- + Number_ _Fat_ _Protein_ hydrates_ _Water_ _Ash_ + 1 8.5 3.0 22.50 65.0 1.0 + 2 14.0 2.2 20.00 63.0 0.8 + 3 8.0 4.0 21.10 66.0 0.9 + +Ice-cream is often considered a possible source of ptomaine poison and +typhoid fever. If not properly handled and allowed to melt and then +returned and refrozen or made from poor materials, there may be danger +of disease. But under the sanitary condition of most of the plants, +especially the large ones, there is no more danger from ice-cream +poisoning than from any other class of food. + + +=188. Locating a market.=--Believing that there is a general demand for +ice-cream, the question naturally follows where is the most desirable +location or market. Because of the large number of consumers, the +city naturally offers the best market. If a large plant is planned, +the usual system is to wholesale the ice-cream to the retailer. If a +smaller plant is desired, the market may be a retail business only; +in this case it may be a hotel, drug-store, soda fountain or summer +resort. Several creameries are located on trunk lines of improved roads +and make ice-cream as a side line, catering entirely to automobile +parties. + + +=189. Method of delivery.=--For the retailer the question of delivery +is very simple, but for the wholesaler it is a very perplexing problem. +There are three ways by which the wholesaler may make delivery: by +express, automobile truck, wagons and horses. + +If the plant is in a large city, the ice-cream may be shipped by +express to retailers in the surrounding small towns. The distance +that shipments can be made by express depends on the facilities of the +railroad. If on a main line with fast trains, shipments may be sent +300-500 miles. Ice-cream should not be shipped so far that it will +soften before it reaches the retailer. + +In the city, the manufacturer must decide which is the more economical, +to use horses and wagons or automobiles. Each has its advantages and +disadvantages, some of which are as follows: + + Advantage of automobile truck: + + 1. Can make quicker delivery than horses and wagon. + + 2. Can carry larger load. + + Disadvantage of automobile truck: + + 1. Large initial cost. + + 2. Requires higher salaried person to operate it than to drive horses. + + 3. Cannot be used year round in some snowy localities. + + 4. Engine may be left running while making delivery. This is + expensive. + + 5. Large loss in case of accident. + + Advantage of horses and wagons: + + 1. Can be used year around. + + 2. Easy to get person to drive horses. + + 3. Not as expensive as large truck to purchase. + + Disadvantages of horses and wagons: + + 1. Slower than automobile truck. + + 2. Liable to tire out in hot weather. + + +=190. Cost of delivery.=--This is so variable that even average figures +would be misleading. The cost of delivery should be based both on the +cost a gallon and the cost a load. These figures should be watched and +a reason found for a marked increase. Otherwise, the cost of delivery +may grow so that it will consume all profits. One of the large items is +the ice necessary to pack the ice-cream in the retailer’s cabinets. + +[Illustration: FIG. 77.--Ice-cream packing tubs.] + + +=191. Packages used for delivery.=--When drawn from the freezer, the +ice-cream is placed in pack-cans or brick molds. When delivery is made +to the retailer, the ice-cream is usually left in the pack-can. For +delivery by express or to the individual consumer, the can is packed in +a tub with ice and salt. The size of the tub varies with that of the +pack-can. (Fig. 77.) The small tubs usually have bails and the large +tubs handles on the side. For city delivery of wholesale ice-cream, the +wagon or auto truck (Fig. 78) is equipped with a cabinet and the cans +packed in these cabinets. This eliminates the heavy tubs. Ice and salt +are carried for packing the ice-cream in the retailer’s cabinet. Most +manufacturers furnish the retailer with a cabinet (Fig. 79) in which +the ice-cream is packed until retailed. These cabinets are usually +insulated. They are made in various sizes to hold one or several +pack-cans of ice-cream. In the cabinet is usually a form which fits +around each can so that it may be removed and another full one put in +without the ice caving in. This form has numerous holes in it so that +the cold air and brine can get to the pack-can. The cabinet is fitted +with a large cover in which are smaller openings and covers for each +can. These smaller openings are used when dipping the ice-cream. + +[Illustration: FIG. 78.--Auto delivery truck for ice-cream.] + +Before delivery to the consumer or the retailer, the brick ice-cream +is usually taken from the mold and wrapped in paper. This eliminates +the return of the metal form. These bricks may then be packed in ice +and salt or simply wrapped in additional paper, depending on how long +the ice-cream must be kept before it is to be consumed. Several paper +carriers have been devised, but they are not in general use. + +The retailer makes his deliveries directly to the consumer, either to +be eaten immediately or carried home. + +When delivery is made to be consumed immediately, the ice-cream is +dished with a measuring disher and placed in an individual dish. There +are a large number of styles of these dishers. (Fig. 80.) Each has some +sort of a knife or scraper to remove the ice-cream from the disher. +The size is expressed in the number that it takes to make a quart. The +disher is used as the measure whether the ice-cream is sold by the +dish, in the soda glass or cone. A large amount is sold in the latter. +There is no objection to the cone itself if it is made of pure harmless +materials. It is often sold from push carts and venders’ wagons, where +there is great opportunity for dirt to get into the ice-cream both +before and after it reaches the consumers’ hands. + +[Illustration: FIG. 79.--Ice-cream cabinet with sides cut away showing +insulation and perforated cylinders in which the pack-cans of ice-cream +set.] + +Another device through which a large amount of ice-cream is sold is +the ice-cream sandwich machine. This places a slice of brick ice-cream +between two wafers. + +When the ice-cream is sold by the retailer to the consumer to be +carried away and consumed later, it is packed in a heavy manilla paper +pail. These vary in size from a pint to two quarts. If the ice-cream is +hard and the pail wrapped in paper, it may be held for an hour or more +before it begins to melt. + +While the ice-cream may be made of high grade materials and under the +most sanitary conditions, many of the places where it is retailed are +not clean. The single-service paper plate and spoon are to be desired +in preference to the dish and silver-plated spoon which is rinsed off +in cold water. It is to the advantage of the manufacturer to see that +the places where his ice-cream is sold are kept in a clean sanitary +condition. + +[Illustration: FIG. 80.--Different styles of ice-cream dishers.] + + +=192. Advertising.=--The manufacturer must keep the attention of the +public centered on his ice-cream. This can be done only by advertising. +There are several ways, but the best is to let the product advertise +itself. If an ice-cream appeals to the desires of the consumer and is +uniform, it will be in demand. + +The newspapers may be employed also as an advertising medium. In +some localities the advertisement has appeared for so long in some +particular space in the paper that the consumer has become accustomed +to look there to learn what special ice-creams will be made for +holidays and Sundays. + +The paid reading advertisement in the newspaper is a form commonly +used. This differs from the ordinary form in being printed the same +as any news item. It should not be too long and should be concise and +clear to the reader. + +The society columns should be watched and an effort made to sell one’s +ice-cream at any large gathering. This is especially true of church +functions. The person in charge may be communicated with either by +telephone or a neat attractive letter. Extra effort should be made +to have the ice-cream of good quality. It may not be profitable to +furnish ice-cream at these functions, but if the advertising feature is +considered it will be very valuable. + +The bill-board is another means of advertising and is very effective +in impressing the name of the ice-cream on the public. It is usually +expensive. + +The results of advertising are ordinarily hard to measure exactly, but +it is a necessary part of the business. The value of advertising in +the winter, when there is not a large demand for ice-cream and many +specialties have to be manufactured, should not be overlooked. There +are many schemes for advertising, and which will be tried and which +rejected will have to be determined by the manufacturer. The underlying +principle is the same in all. They should be attractive; they should +state some fact about the ice-cream; the wording should be such as to +induce the reader to try a dish. The value of advertising is especially +difficult for a beginner to see. The amount of money that can or should +be used for advertising will have to be determined by several facts, +such as number of local newspapers, number of towns where ice-cream is +sold, amount of education necessary to create a demand. + +Under no circumstances, in any advertisement or in any other way, +should a manufacturer run down the quality of his competitors’ products. + +It is often desirable to have some short attractive expression to use +with the advertisement. + + +=193. Salesmen.=--In the large plants, salesmen are necessary to call +on the trade to sell the ice-cream and adjust any differences that +may arise. The kind of salesman has much to do with the success of +the business. He should be neat and clean in appearance; he must have +the faculty of getting along with people; he must have good business +ability and be able to make sales. It is not the first sale that counts +but the repeated orders that are necessary to put the business on a +firm foundation. + + +BUSINESS MANAGEMENT + +The success of a plant is not alone in being able to make ice-cream +of good quality, although this may be the major item. The business +management is very important. This consists of the buying, handling the +workmen, making the sales and in general keeping track of the financial +end of the plant. In many cases it is necessary to check up the losses. + + +=194. Purchase of raw material.=--All raw materials used in the +ice-cream should be purchased on the basis of their composition +rather than by quantity. For example, it is very poor business to buy +milk and cream for a certain price a quart or gallon regardless of +the percentage of fat contained. The percentage of fat in the milk +is largely influenced by the season of the year and the lactation +period. Even more variable is the percentage of fat in the cream, the +fat-content varying from the same creamery or same separator. Some of +the causes of variation in the test of cream are: 1. Adjustment of the +cream screw; 2. Richness of milk separated; 3. Amount of material used +to flush the bowl; 4. Speed of the separator; 5. Temperature of milk +when separated; 6. Rate of flow of the milk to the machine. + +The composition of the other materials will vary the same as does the +milk and cream. Each shipment should be tested to make sure that it is +of the proper composition. This may take some time, but it pays in the +end. + + +=195. Price of dairy products.=--There is no market quotation for +any except the manufactured dairy products such as butter and +cheese. Ordinarily the price of milk and cream follows that of these +manufactured products very closely. The price of butter and cheese +are quoted daily in New York City in the “Price Current” published by +the Urner Barry Company. From this the price of milk and cream can be +estimated. In some cases, the price of the fat in the cream is based on +the price of butter. + + +=196. Book-keeping system.=--A simple yet complete set of books should +be kept. A cost system seems best adapted and the most simple. + +To obtain a cost system it is very essential that every penny should +be accounted for and charged to the account for which the expenditure +was made. The numerous accounts that will have to be maintained in +order to keep this system should be classified under the headings +of production costs and sales costs. In opening the accounts for +production cost, it is necessary that the following heads should be +carried: + + 1. Milk, cream, butter. Express should be added to the cost of the + above where any of the same is shipped. + + 2. Labor. Salaries for ice-cream maker, mixers, and helper. The + remaining help throughout the plant is carried under a different + heading which does not apply specifically to the production + department. + + 3. Supplies used. This account should be carried under several + different headings, as: + + (a) Sugar + (b) Milk powder + (c) Gelatine + (d) Gum + (e) Fruits + (f) Extracts + (g) Miscellaneous + + 4. Ice and salt (when ice and salt are used for the freezing of + the cream). But in case mechanical refrigeration is employed for + freezing and ice and salt for hardening, it should be charged to the + production cost; otherwise it should be figured into the sales cost + just the same as delivery or other expense. + + 5. Water and steam. + + 6. Sundry expense. + +By keeping these accounts monthly, the production cost for every month +is computed for the year. + +Sales cost should include: + + 1. Rent. + 2. Salaries. + (a) Executive. + (b) Office. + (c) Salesmen. + (d) Delivery drivers. + (e) Labor. (Can-washers and such other help as is employed). + 3. Advertising. + 4. Ice (as used in packing for deliveries). + 5. Miscellaneous expenses. + 6. Taxes. + 7. Insurance. + 8. Bad debts. + 9. Postage and stamps. + 10. Trucks, or horse and wagon expense. + 11. Traveling expense. + 12. Telephone and telegraphic expenses. + 13. Salt. + 14. Depreciation. + 15. Repairs and replacements. + 16. Stationery. + 17. Shrinkage. + 18. Such other items of sales cost as you may see fit to carry under + separate headings. + +Taking the number of gallons sold, it is an easy matter to divide +this into any one of the numerous accounts under either the head of +production or sales cost, which will give the cost a gallon of this +account and place the manager in a position to keep in touch with +every account as to the actual cost a gallon each month. By making +comparisons month after month, it will be easy to determine wherein the +costs are excessive. + + +=197. Shipping clerk.=--No ice-cream business is too small or too +large to have a shipping clerk. In a small plant, the shipping may +not require all one man’s time so that he may have other duties. The +shipping platform and office of the shipping clerk in a large ice-cream +plant is shown in Fig. 81. It is the duty of the shipping clerk to see +that the orders are properly put up and that they are delivered on +time. He must check the ice-cream to the drivers and see that each has +the correct amount of salt and ice. It is sometimes the custom of the +drivers to take extra ice and salt and sell it on the side. He must +also check back any ice-cream returned by the drivers. The position +of shipping clerk is one of the most important in the whole business +management. + +[Illustration: FIG. 81.--Shipping platform and office of shipping clerk +in a large ice-cream plant.] + + +=198. Report blanks.=--Every person who has charge of any part of +the ice-cream business should make a report. By means of these daily +reports, any leaks or losses may be checked up. It also makes easy the +keeping track of the business. Forms for these reports are not included +because the demand in each plant would probably be different. The +receiving-room report should show the amount of milk and milk products +received and the percentage of fat in each and the total receipts. +The mixing-room report should indicate the amount of materials used. +The freezing-room report should show the number of freezers of +ice-cream made, the swell obtained in each and the total gallons. The +shipping-room report should tell the number of gallons shipped out. +The drivers’ report should show the amount of ice-cream received, the +amount returned and the amount sold, to whom sold, whether cash or +credit, and the cash and credit should equal the amount sold. These +reports may be combined more or less, depending on the size of the +plant. A loose-leaf or card system for filing in many cases would +reduce the office work. + + +=199. Losses.=--In any business there are more or less losses. These +are usually inversely in proportion to the efficiency of the business +management. In ice-cream marketing, certain leaks or losses are liable +to occur and these should receive special mention. + + +=200. Pack-cans and tubs.=--Undoubtedly there is no part of the +business that causes the manager more anxiety than the return of the +empty pack-cans and tubs. This is especially true when a considerable +part of the ice-cream is shipped by express. Many schemes have been +tried to return these tubs, such as paying the drivers a percentage +for the return of a certain number, charging the person to whom the +ice-cream was sold for the can and tub, hiring a special man to +look up the can and tub, and many others. The one commonly used by +manufacturers is to have a distinctive color on the tub, their name +and address and also a number. The shipping tags are made with a stub +that is perforated so that it can be detached easily. When the tag +is attached to the tub, the number is placed on both the tag and the +stub. The stub should contain date and name and address of the party +to whom shipped. It is often desirable to have the gallons and kind of +ice-cream shipped on both the stub and the tag. This stub is filed in +the office and when the tub is returned the tag is taken off and sent +in and the stub bearing the same tub number put with it, indicating +that tub has been returned. By looking at the stubs for which the +corresponding tags have not been returned, it can be seen readily to +whom, where, and when the tubs were shipped and what parties are not +returning the empties. + + +=201. Rusty pack-cans.=--Because of the salt that must be used to +harden the ice-cream, more or less gets on to the pack-cans and rusts +them, especially if they are not washed as soon as emptied. These rusty +cans may be retinned. Another satisfactory plan is to line the can with +heavy manilla paper. These liners may be purchased to fit any size +pack-can. + + +=202. Soft ice-cream.=--Often the top of the can of ice-cream will +become soft, due to the lack of salt and ice on top. Sufficient may +have been put on but it jarred off while handling. This loss can be +avoided by tying a piece of heavy paper or burlap over the top of the +can. Heavy canvas covers may be purchased. + +Sometimes a large amount of refrigeration is lost by putting the +ice-cream into the hardening-room through the large door where persons +pass in and out. A small revolving door (Fig. 82) will reduce this +loss. There is a very rapid change of air when the hardening-room door +is opened. The greater the difference in temperature, the more rapid +the change. Soft ice-cream soon ruins the reputation of the business. + +[Illustration: FIG. 82.--Revolving door used for putting the ice-cream +into the hardening-room.] + + +=203. Transferring.=--When drawn from the freezer, the ice-cream should +be put into the size pack-can in which it will be delivered to the +consumer or retailer. If it is necessary to transfer from one can to +another, there is a big loss in volume. This loss is probably caused by +squeezing the ice-cream into the other container, which closes the air +spaces. + +When the ice-cream is handled in the retail store, a loss may be caused +by the heaping up of the dishes. Several scrapers or levelers have been +devised to insure a uniform sized dish. If the dishers are kept in +hot water, they will work much better in hard ice-cream. Some sort of +scraper, of which there are several on the market, should be used to +scrape the ice-cream from the sides of the can. + + +LAWS + +Several laws apply to ice-cream. Some of these refer to the production +of the milk and the balance are standard of quality based on chemical +composition or standards for materials used. + + +=204. Sanitary conditions and adulterated milk and cream.=--Most of the +states have laws dealing with the sanitary conditions under which milk +and cream may be produced. The following law[52] of Wisconsin is a good +example: + +[52] Dairy Laws of Wisconsin 1916, section 4607a. + +“Adulterated milk, what constitutes. Section 4607a. In all prosecutions +under the preceding section, or any other section of these statutes, or +laws amendatory thereof or supplementary thereto, relating to the sale +of adulterated milk or adulterated cream, the term adulterated milk +shall mean: Milk containing less than three per centum of milk fat, or +milk containing less than eight and one-half per centum of milk solids +not fat, or milk drawn from cows within eight days before or four days +after parturition, or milk from which any part of the cream has been +removed, or milk which has been diluted with water or any other fluid, +or milk to which has been added or into which has been introduced any +coloring matter or chemical or preservative or deleterious or filthy +substance or any foreign substance whatsoever, or milk drawn from cows +kept in a filthy or unhealthy condition, or milk drawn from any sick or +diseased cow or cow having ulcers or other running sores, or milk drawn +from cows fed unwholesome food, or milk in any stage of putrefaction, +or milk contaminated by being kept in stables containing cattle or +other animals. The term adulterated cream shall mean containing less +than eighteen per centum of milk fat, or cream taken from milk drawn +from cows within eight days before or four days after parturition, or +cream from milk to which has been added or introduced any coloring +matter or chemical or preservative or deleterious or filthy substance +or any foreign substance whatsoever, or cream from milk drawn from +cows kept in a filthy or unhealthy condition, or cream from milk +drawn from any sick or diseased cow or cow having ulcers or other +running sores, or cream from milk drawn from cows fed unwholesome +food, or cream contaminated by being kept in stable containing cattle +or other animals, or cream to which has been added or into which has +been introduced any coloring matter or chemical or preservative or +deleterious or filthy substance or any foreign substance whatsoever, or +cream in any stage of putrefaction; provided, that nothing in this act +shall be construed to prohibit the sale of pasteurized milk or cream +to which viscogen or sucrate of lime has been added solely for the +purpose of restoring the viscosity, if the same be distinctly labeled +in such manner as to advise the purchaser of its true character; and +providing that nothing in this act shall be construed as prohibiting +the sale of milk commonly known as ‘skimmed milk,’ when the same is +sold as and for ‘skimmed milk.’ Milk drawn from cows within eight days +before or four days after parturition, or milk to which has been added +or into which has been introduced any coloring matter or chemical or +preservative or deleterious or filthy substance, or milk drawn from +cows kept in a filthy or unclean condition, or milk drawn from any sick +or diseased cow or cow having ulcers or other running sores, or milk +drawn from cows fed unwholesome food, or milk contaminated by being +kept in stables containing cattle or other animals and cream from any +such milk, or cream in any stage of putrefaction are hereby declared to +be unclean and unsanitary milk or unclean and unsanitary cream, as the +case may be.” + +Most of the states have laws which determine the legal standard of +milk. Anyone selling milk which does not meet the legal standard is +liable to be fined. The laws of most states prohibit the taking of +anything from or the adding of anything to the milk. This prohibits +skimming and watering. Skim-milk must be sold as such. + + +=205. Babcock test.=--Some states have laws specifying that all +glassware used in the Babcock test shall be standardized. Standard +glassware shall bear a certain brand to identify it. This brand is +placed on it after being tested by the proper state official. Some of +the states have laws requiring the operator of the Babcock test to +procure a license. + + +=206. Purchasers or vender’s license.=--In some states a concern to +purchase milk or cream from the producer must have a license. This is +to prevent parties not financially responsible from buying milk and +later beating the producer. The license is given only on the filing of +a bond. + +In some cities ice-cream cannot be sold without a license. This is for +the purpose of controlling sanitary conditions. + + +=207. Legal standards.=--Most states have legal standards for dairy +products. The standard for the different states is given in Table[53] +XV. + +[53] Melvin, A. D., “Legal standards for dairy products,” A8, 1916. + + + U. S. DEPARTMENT OF AGRICULTURE + BUREAU OF ANIMAL INDUSTRY + A. D. MELVIN, Chief of Bureau + + LEGAL STANDARDS FOR DAIRY PRODUCTS + + (_Revised to July 1, 1915_) + + In the following statement, prepared in the Dairy Division of the + Bureau of Animal Industry, are given the standards for dairy products + as established in the several states, including Alaska, the District + of Columbia, Hawaii, the Philippines, and Porto Rico. In all cases, + unless otherwise expressed, the percentages stated represent minimum + standards. + + The department publishes these figures as given by various state + authorities, but does not guarantee the correctness of the standards + given. + +TABLE XV.--Legal Standards for Dairy Products. + +TABLE XV--Legal Standards for Dairy Products--_Continued_. + + --------------------+----------------------+--------+------+ + | | | | + | | SKIM | | + | MILK | MILK | CREAM| + --------------------+-------+--------+-----+--------+------+ + |_Total |_Solids | | _Total | | + STATES |solids_|not fat_|_Fat_| solids_| _Fat_| + --------------------+-------+--------+-----+--------+------+ + | Per| Per| Per| Per| Per| + | ct.| ct.| ct.| ct.| ct.| + Alabama[54] | ...| ...| ...| ...| ...| + Alaska[55] | ...| ...| ...| ...| ...| + Arizona[56] | ...| ...| ...| ...| ...| + Arkansas[54] | ...| ...| ...| ...| ...| + California | ...| 8.50| 3.00| 8.80| 18.0| + Colorado | ...| ...| 3.00| ...| 16.0| + Connecticut | 11.75| 8.50| 3.25| ...| 16.0| + Delaware[54] | ...| ...| ...| ...| ...| + District of Columbia| 12.50| 9.00| 3.50| 9.30| 20.0| + Florida | ...| 8.50| 3.25| 9.25| 18.0| + Georgia | ...| 8.50| 3.25| 9.25| 18.0| + Hawaii | 11.50| ...| 2.50| ...| 18.0| + Idaho | 11.20| 8.00| 3.20| 9.30| 18.0| + Illinois | ...| 8.50| 3.00| 9.25| 18.0| + Indiana | ...| 8.50| 3.25| 9.25| 18.0| + Iowa | 12.00| ...| 3.00| ...| 16.0| + Kansas | ...| ...| 3.25| ...| 18.0| + Kentucky | ...| 8.50| 3.25| 9.25| 18.0| + Louisiana | ...| 8.50| 3.50| 8.00|([60])| + Maine | 11.75| 8.50| 3.25| ...| 18.0| + Maryland | 12.50| ...| 3.50| 9.25| 18.0| + Massachusetts | 12.15| ...| 3.35|[67]9.30| 15.0| + Michigan | 12.50| ...| 3.00| ...| 18.0| + Minnesota | 13.00| 9.75| 3.25| ...| 20.0| + Mississippi[60] | ...| ...| ...| ...| ...| + Missouri | 12.00| 8.75| 3.25| 9.25| 18.0| + Montana | 11.75| 8.50| 3.25| ...| 20.0| + Nebraska | ...| ...| 3.00| ...| 18.0| + New Hampshire | 12.00| ...| ...| 8.50| 18.0| + New Jersey | 11.50| ...| 3.00| 9.25| 16.0| + New Mexico[54] | ...| ...| ...| ...| ...| + Nevada | 11.75| 8.50| 3.25| 9.25| 18.0| + New York | 11.50| ...| 3.00| ...| 18.0| + North Carolina | 11.75| 8.50| 3.25| 9.25| 18.0| + North Dakota | 12.00| ...| 3.00| ...| 15.0| + Ohio | 12.00| ...| 3.00| ...| ...| + Oklahoma[68] | ...| ...| ...| ...| ...| + Oregon | 11.70| 8.50| 3.20| ...| 18.0| + Pennsylvania | 12.00| ...| 3.25| ([60])| 18.0| + Philippine Islands | 11.75| 8.50| 3.25| 9.25| 18.0| + Porto Rico[68] | ...| ...| ...| ...| ...| + Rhode Island | 12.00| ...| 2.50| ...| ...| + South Carolina[54] | ...| ...| ...| ...| ...| + South Dakota | ...| 8.50| 3.25| 9.25| 18.0| + Tennessee | 12.00| 8.50| 3.50| 9.00| 20.0| + Texas | 12.00| 8.50| 3.25| 9.25| 18.0| + Utah | 12.00| 8.80| 3.20| ...| 18.0| + Vermont | 11.75| 8.50| 3.25| 9.25| 18.0| + Virginia | ...| 8.50| 3.25| 9.25| 18.0| + Washington | 12.00| 8.75| 3.25| 9.30| 18.0| + West Virginia[54] | ...| ...| ...| ...| ...| + Wisconsin | ...| 8.50| 3.00| 9.00| 18.0| + Wyoming[54] | ...| ...| ...| ...| ...| + United States | ...| 8.50| 3.25| 9.25| 18.0| + See notes on page 269. + + --------------------+-----------------------+-----------------+ + | | | + | | CONDENSED MILK | + | BUTTER | (SWEETENED) | + --------------------+------+---------+------+-------+---------+ + | | | |_Total | | + STATES | _Fat_| _Water_|_Salt_|solids_| _Fat_| + --------------------+------+---------+------+-------+---------+ + | Per| Per| Per| Per| Per| + | ct.| ct.| ct.| ct.| ct.| + Alabama[54] | ...| ...| ...| ...| ...| + Alaska[55] | ...| ...| ...| ...| ...| + Arizona[56] | ...| ...| ...| ...| ...| + Arkansas[54] | ...| ...| ...| ...| ...| + California | 80.0| ...| ...| 24.5| 7.70| + Colorado | 80.0| 16.00| ...| 28.0| 7.70| + Connecticut |([60])| ([60])|([60])| 28.0|[57]31.00| + Delaware[54] | ...| ...| ...| ...| ...| + District of Columbia| 83.0| 12.00| 5.00| ([61])| ([61])| + Florida | 82.5| ...| ...| 28.0| 7.70| + Georgia | 82.5| 16.00| ...| ([60])| ([60])| + Hawaii | ...| ...| ...| ...| ...| + Idaho | 82.5| 16.00| ...| 28.0|[57]27.60| + Illinois | 82.5| ...| ...| 28.0| 7.70| + Indiana | 82.5| 16.00| ...| 34.3| 7.80| + Iowa | 80.0| ...| ...| ([60])| ([60])| + Kansas | 80.0| 16.00| ...| ...| ...| + Kentucky | 82.5| ...| ...| 28.0|[57]27.66| + Louisiana |([60])| ([60])|([60])| ([60])| ([60])| + Maine | ...| ...| ...| 26.5|[57]29.50| + Maryland | ...| ...| ...| 34.3| 7.80| + Massachusetts | ...| ...| ...| ([68])| ([68])| + Michigan | 80.0| ...| ...| ([60])| ([60])| + Minnesota | ...| 16.00| ...| 28.0| 8.00| + Mississippi[60] | ...| ...| ...| ...| ...| + Missouri | 82.5| ...| ...| 28.0|[57]27.67| + Montana | 82.5| 16.00| ...| ...| ...| + Nebraska | ...| ...| ...| ...| ...| + New Hampshire | 80.0| 16.00| ...| ([60])| ([60])| + New Jersey | 82.5| ...| ...| ...| ...| + New Mexico[54] | ...| ...| ...| ...| ...| + Nevada | 82.5| 16.00| ...| 28.0|[57]27.50| + New York | ...| ...| ...| ([72])| ([72])| + North Carolina | 82.5| ...| ...| 25.5| 7.80| + North Dakota |([60])| ([60])|([60])| ([60])| ([60])| + Ohio | ...| ...| ...| ([75])| ([75])| + Oklahoma[68] | ...| ...| ...| ...| ...| + Oregon | 80.0| 16.00| ...| ...| ...| + Pennsylvania |([60])| ([60])|([60])| ([60])| ([60])| + Philippine Islands | 82.5| ...| ...| 28.0|[57]27.50| + Porto Rico[68] | ...| ...| ...| ...| ...| + Rhode Island | 82.5| ...| ...| 25.0| 7.80| + South Carolina[54] | ...| ...| ...| ...| ...| + South Dakota | 80.0| ...| ...| 28.0|[57]27.50| + Tennessee | 82.5| 15.99| ...| 25.5| 7.80| + Texas | 82.5| ...| ...| ([60])| ([60])| + Utah | 80.0| 16.00| ...| ([60])| ([60])| + Vermont | 82.5| ...| ...| 28.0|[57]27.50| + Virginia | 82.5| 16.00| ...| 28.0|[57]27.50| + Washington | ...| ...| ...| ...| ...| + West Virginia[54] | ...| ...| ...| ...| ...| + Wisconsin | 82.5| ...| ...| 28.0| 8.00| + Wyoming[54] | ...| ...| ...| ...| ...| + United States | 82.5|[80]16.00| ...| 28.0|[57]27.50| + + --------------------+-----------------+-------------+------------- + | | | ICE CREAM + | EVAPORATED MILK | ICE CREAM | (FRUIT + | (UNSWEETENED) | (PLAIN) | AND NUT) + --------------------+-------+---------+------+------+------+------ + |_Total | | |_Gela-| |_Gela- + STATES |solids_| _Fat_| _Fat_| tine_| _Fat_| tine_ + --------------------+-------+---------+------+------+------+------ + | Per| Per| Per| Per| Per| Per + | ct.| ct.| ct.| ct.| ct.| ct. + Alabama[54] | ...| ...| ...| ...| ...| ... + Alaska[55] | ...| ...| ...| ...| ...| ... + Arizona[56] | ...| ...| ...| ...| ...| ... + Arkansas[54] | ...| ...| ...| ...| ...| ... + California | 25.5| 7.80| 10.0| 0.6| 8.0| 0.6 + Colorado | ([59])| ([59])| 14.0| ...| 12.0| ... + Connecticut | ([59])| ([59])| ...| ...| ...| ... + Delaware[54] | ...| ...| ...| ...| ...| ... + District of Columbia| ([61])| ([61])| ...|([62])| ...|([62]) + Florida | 24.0| 7.80| 12.0| ...| ...| ... + Georgia | ([60])| ([60])| 12.0| ...| 10.0| ... + Hawaii | ...| ...| ...| ...| ...| ... + Idaho | ([60])| ([60])| 14.0|([63])| 12.0|([63]) + Illinois | 25.5| 7.70| 8.0| ...| 8.0| ... + Indiana | 25.5| 7.80| 8.0| .7| 8.0| .7 + Iowa | ([60])| ([60])| 12.0| 1.0| 10.0| 1.0 + Kansas | ...| ...| 14.0| ...| 12.0| ... + Kentucky | 28.0|[57]27.66| 14.0| ...| 12.0| ... + Louisiana | ([60])| ([60])| 10.0| 1.0| 8.0| 1.0 + Maine | 26.5|[57]29.50| 14.0|([66])| 12.0|([66]) + Maryland | ...| ...| 4.0| ...| 6.0| ... + Massachusetts | ...| ...| 7.0| ...| 7.0| ... + Michigan | ([60])| ([60])| 10.0| .7| 8.0| .7 + Minnesota | 25.5| 7.80| 12.0| ...| 12.0| ... + Mississippi[60] | ...| ...| ...| ...| ...| ... + Missouri | 28.0|[57]27.67| 14.0| ...| 12.0| ... + Montana | ...| ...| 12.0| 1.0| 10.0| 1.0 + Nebraska | ...| ...| 14.0| ...| 12.0| ... + New Hampshire | ([60])| ([60])| 14.0| .2| 14.0| .2 + New Jersey | ...| ...| ...| ...| ...| ... + New Mexico[54] | ...| ...| ...| ...| ...| ... + Nevada | 25.5| 7.80| 14.0| ...| 12.0| ... + New York | ...| ...| ...| ...| ...| ... + North Carolina | 25.5| 7.80| 10.0| ...| 8.0| ... + North Dakota | ([60])| ([60])| 14.0|([73])| 12.0|([73]) + Ohio | ...| ...| ...| ...| ...| ... + Oklahoma[68] | ...| ...| ...| ...| ...| ... + Oregon | 32.3| 7.80| 12.0| 1.0| 9.0| 1.0 + Pennsylvania | ([60])| ([60])| 8.0| .5| 6.0| .5 + Philippine Islands | 25.5| 7.80| 14.0| ...| 12.0| ... + Porto Rico[68] | ...| ...| ...| ...| ...| ... + Rhode Island | 25.0| 7.80| 8.0| 1.0| 8.0| 1.0 + South Carolina[54] | ...| ...| ...| ...| ...| ... + South Dakota | 28.0|[57]27.50| 14.0| ...| 12.0| ... + Tennessee | 25.5| 7.80| 8.0| ...| 7.0| ... + Texas | ([60])| ([60])| 8.0| ...| 6.0| ... + Utah | ([60])| ([60])|([60])|([60])|([60])|([60]) + Vermont | 34.3| 7.80| 14.0| ...| 12.0| ... + Virginia | 28.0|[57]27.50| 8.0|([76])| 8.0|([76]) + Washington | ...| ...| ...| ...| ...| ... + West Virginia[54] | ...| ...| ...| ...| ...| ... + Wisconsin | 28.0| 8.00| 14.0| ...| 12.0| ... + Wyoming[54] | ...| ...| ...| ...| ...| ... + United States | 25.5| 7.8 | 14.0| ...| 12.0| ... + See notes on page 271. + +[54] No state standards. + +[55] No territorial standards. + +[56] Federal standards for all food products. Fillers in ice-cream may +be used if large label is displayed in all places of sale. + +[57] Percentage of fat based on total solids. + +[58] Must be labeled. + +[59] Classed as condensed. + +[60] United States standard. + +[61] United States food and drugs act of 1906 applies to the District +of Columbia. + +[62] Should be labeled. + +[63] Not allowed. + +[64] Must be so branded. + +[65] Defined, but no standard. + +[66] Any amount if fat is maintained. + +[67] Solids in fat. + +[68] Must correspond on stated dilution to state standards for milk. + +[69] Any less than 30. + +[70] All below 45. + +[71] Less than 13 marked skim; 13 to 18, medium skim; 18 or over, +special skim. + +[72] Must correspond to 11.5 per cent solids in crude milk; one-fourth +to be fat. + +[73] Two ounces in 10 gallons if labeled gelatine ice-cream. + +[74] Full cream, 30. Standard, 21. + +[75] Must correspond to 12 per cent of solids in crude milk; one-fourth +to be fat. + +[76] Less than 7.5, skim; 7.5 to 15, three-fourths skim; 15 to 30, half +skim. + +[77] Three-fourths cream, 24; one-half cream, 16; one-fourth cream, 8. +Skim, less than 8. + +[78] Less than 30. + +[79] Less than 30; less than 15 not allowed. + +[80] Less than 16. This applies to all butter made in United States +territory. + +No reports gave standards for powdered milk. + + + + +CHAPTER XVI + +_CONSTRUCTION AND ARRANGEMENT OF THE FACTORY_ + + +The exterior construction of the ice-cream plant is of little +importance as long as the building is large and strong enough to hold +the business, and is neat and clean. The building may be of brick, +wood, hollow tile, cement block or any other satisfactory material. +The interior arrangement should receive careful study and planning. In +a new building, devoted to the manufacture of ice-cream, the details +usually can be included in the plans. However, it is often necessary +to use some building which was not especially constructed or arranged +for ice-cream-making. An old building usually can be rearranged so that +it will be suitable and fairly convenient. It should be large enough +to give sufficient room for the machinery and space for working. If +a new building is being constructed, the plans should be made with a +view of possible needs for enlargements. The building should not be so +large that there will be waste space. This causes unnecessary expense +and requires useless labor to keep clean. Certain considerations should +be kept in mind, whether building a new plant or rearranging an old +building. These are discussed in the following paragraphs. + + +=208. Location of the plant.=--For the ease of delivery, the plant +should be located as near the center of the city as possible. If it is +planned to ship much ice-cream by express, a location near the express +company is desirable. If it is a small plant and expects to conduct a +retail business principally, the location should be on one of the main +streets of the town in order to reach as many of the consuming public +as possible. Usually sewage connections can be secured in any part of +the city so this factor need not be considered. The question of a clean +atmosphere about the factory is of much importance; if located in a +manufacturing section of the city, it is almost impossible to keep the +factory clean because of the smoke and cinders. + +[Illustration: FIG. 83.--Plan of small ice-cream plant.] + + +=209. Arrangement of machinery.=--Because of the large number of +difficult makes of the same kind of machine and the variation in size +of the different types, it is impossible to make exact plans without +knowing the exact size of the machine. In a small plant all the +machinery is usually located on the same floor. Such an arrangement +is shown in Fig. 83. This is intended as both a retail and wholesale +plant. The retail salesroom might be omitted and the plans used for a +small wholesale plant. A small boiler for heating water for washing +and sterilizing the utensils might be located in the basement. If +desired, tanks for the making of ice might also be placed in the +basement. Such a plan is shown in Fig. 84. The arrangement should +be such as to follow the natural sequence of the process as far as +possible. The second story or attic might be used as a storeroom. + +[Illustration: FIG. 84.--Basement plan of large ice-cream plant.] + +The exact location of the machines is not indicated, since this will +depend on their size. However, the rooms are large enough so that the +exact placing of the machines is not a difficult problem. + +The basement, first and second floor plans of a wholesale plant are +shown in Figs. 84, 85, 86. For the reasons previously mentioned, the +exact location of the machines is not indicated. + +[Illustration: FIG. 85.--First floor plan of plant shown in Fig. 84.] + +[Illustration: FIG. 86.--Second floor plan of plant shown in Figs. 84 +and 85.] + + +=210. Loading platform.=--There should be ample room for the loading +of the ice-cream and the unloading of the empties and the returned +ice-cream. The loading platform should be protected from the storms. +Such a platform in a large ice-cream plant is shown in Fig. 87; note +the chutes for the loading of crushed ice. Often the wagon or auto +storage is a part of the same space as the loading platform. + +[Illustration: FIG. 87.--A loading platform in a large ice-cream plant.] + + +=211. Light.=--The question of proper light in the ice-cream plant has +been neglected. This may be because the buildings in the city are close +together and it is difficult to get light except from the ends of the +building which are exposed to the street or alley. Many of the smaller +plants are in the basement and in these it is impossible to have +anything but artificial light. The natural light may be secured from +windows or skylights. The sacrifice of space for skylights is shown +in Fig. 88. Light seems to be a stimulus to keep the plant clean. It +also makes it more pleasant and cheerful. It is believed that sunlight +tends to disperse disease germs. It would be a great benefit if it were +necessary for all ice-cream plants to have a certain amount of window +space in each room. + + +=212. Ventilation.=--Next to light, the question of proper ventilation +is neglected. The windows, doors and skylights may serve as a means. If +they are used for this purpose and are screened against flies, there is +danger of considerable dirt getting in. In some of the large plants, +a very extensive system of ventilation is employed. In these, no air +is allowed to enter except through this system, and all the entering +air is either filtered or washed or both. The air is circulated by a +large fan. This insures only clean pure air entering the manufacturing +rooms. The importance of pure air about food products cannot be +over-emphasized. It is difficult to ventilate a basement properly. All +doors and windows should be screened against flies. There should be no +stable in connection with the manufacturing rooms. + +[Illustration: FIG. 88.--The value of skylights is shown by this well +lighted freezing-room, considerable floor space above being sacrificed +for this purpose.] + + +=213. Floors.=--The floors should be of some non-absorbent waterproof +material that can be cleansed easily. Concrete undoubtedly is the +best material, when both cost and adaptability are considered. The +floor should slope towards drains which will carry away the water. +These should be connected with the city sewage system, septic tank, +or cesspool. If sewage connections cannot be obtained, a cesspool or +septic tank must be installed, preferably the latter. The drains should +have sealed traps to prevent the escape of sewage gas into the plant. +Some prefer to have the drain in the center of the floor and others at +the side; this is immaterial so long as it works effectively. + + +=214. Ceilings and side-walls.=--The ceilings and side-walls should be +kept clean. If they are constructed of various tiles or plasters, they +can be washed. If made of wood, they should be kept painted. If painted +white or light colored, it helps to make the room lighter. + + +=215. Sinks and cupboards.=--Proper facilities should be provided +properly to wash and sterilize the utensils. There is usually a lack of +sinks for washing utensils in the ice-cream plants. After the utensils +are properly cleaned, there should be a place where they can be kept +until wanted again. Tables, shelves, and cupboards offer suitable +places to keep utensils when not in use. + + +=216. Locker-rooms.=--Every plant where food products are manufactured +should be provided with a locker-room in which the employees can +change their clothes. Each person should have a separate locker. +The locker-room should also contain a lavatory and shower-baths and +facilities for washing the hands and face. The locker-room should be +kept neat and clean. + + +=217. Cleanliness.=--The average consumer appreciates food products +produced in clean plants. There is no better advertisement than to +invite the public to see the factory. The plant and employees should +be so clean that it will make a strong impression and the visitors in +turn will tell others. The employees should wear clean white suits. If +the plant is large enough, a laundry for washing may be included in the +equipment. + + +=218. Cleaning utensils.=--Few ice-cream-makers know how to clean the +utensils thoroughly. The following is a good method: (1) Rinse off the +milk and grease with lukewarm water. (2) Wash in hot water as hot as +the hands can stand. To this water add some washing-powder to cut the +grease. There is a tendency to use too much washing-powder. Enough +to burn the hands should not be used. (3) Scrub the utensils in the +washing solution with a brush. Do not use a cloth. (4) Rinse with warm +water. (5) Scald with boiling water or live steam. The utensils may be +dipped in boiling water or boiling water may be poured over them. They +may be placed in a sterilizer and live steam applied. The heating kills +most of the bacteria and is usually sufficient to dry the utensils. In +no case should a cloth be employed for drying. + + +=219. Cleaning the floor.=--The proper cleaning of the floor is not +considered by many as a necessary part of the manufacturing process. +However, it is very important in the clean appearance of the plant +that the floor be clean. Often too much water is used and yet the +floor is not clean. The best method is as follows: (1) Rinse the floor +with water thrown from a pail; (2) sweep up all loose dirt; (3) make +a hot solution of washing-powder, a little stronger than for washing +utensils, and spread this on the floor and scrub with floor broom, +scrub toward the drain; (4) rinse with clean warm water thrown from a +pail. If the hose is used, too much time and water are wasted. + + +=220. Storeroom and workshop.=--No ice-cream plant is complete unless +it includes a storeroom and workshop. More or less supplies must be +stored and it helps the general appearance of the plant materially if +there is a special room for this purpose. More or less repairs are +necessary, so that a workshop should be provided. It is desirable to +have this near or a part of the storeroom. + + +=221. Sanitary codes.=--Many states have ice-cream-makers’ +organizations or associations. The state organizations are united in a +National Association of Ice-Cream-Makers. Many of these associations +have adapted sanitary codes. Following are some samples: + +_Ohio sanitary code:_ + +1. All factories or shops shall be open to the public at all times. + +2. Workrooms must be thoroughly clean and free from dust, foul +atmosphere and contamination, and shall be well lighted, to the +end that there shall be no dark corners where rubbish or dirt may +accumulate. + +3. One square foot of glass surface exposed to natural light, +unobscured by buildings or other devices nearer than ten feet, for each +ten square feet of floor surface of the workrooms must be provided. +Basements shall not be used as workrooms unless these provisions can be +met. + +4. Garbage and all waste material subject to decomposition, must +be removed daily to the outside and deposited in a can provided +exclusively for this purpose, composed of impervious material and +provided with a tight fitting cover. Covers must be kept on the cans at +all times except when entering or removing the material. + +5. The side-walls and ceilings of all workrooms shall be well +plastered, tiled or wainscoated or ceiled with metal or lumber and +shall be well painted to the end that they may be readily cleaned and +they shall be kept free from dust, dirt and foreign matter and clean at +all times. + +6. The floors of all workrooms shall be impermeable and be made of +cement, tile laid in cement, or other suitable non-absorbent material +which can be flushed and washed clean with water. Floors shall be +sloped to one or more drains which must be properly connected to the +sewerage system. + +7. Store and storage rooms for materials must be kept clean and free +from objectionable odors. + +8. Doors, windows and other openings of every workroom shall be +screened during the fly season with screens not coarser than 14-mesh +wire gauze, or in any other manner equally effective keep the workrooms +free from flies and vermin at all seasons of the year. + +9. All factories or shops shall have convenient toilet rooms, separate +and apart from the workrooms, and no toilet rooms shall be within or +connected directly with a workroom, either by a door, window or other +opening. The floors of the toilet room shall be of cement, tile or +other non-absorbent material, and shall be kept clean at all times. +Toilet rooms shall be furnished with separate ventilating flues or +pipes discharging into soil pipes or on the outside of the building in +which they are situated. Lavatories and washrooms shall be adjacent +to toilet rooms and shall be supplied with soap, running water and +clean towels and shall be maintained in a sanitary condition. Workroom +employees before beginning work and after visiting toilet rooms shall +wash their hands and arms thoroughly in clean water. + +10. No person shall live or sleep in any building used as a factory +or shop, unless the factory or shop is separated by impervious walls, +without doors or windows or other openings from the parts of the +building used for living or sleeping purposes. + +11. No horses, cows or other animals shall be stabled or kept in +any building where ice-cream is made, unless the factory or shop is +separated from the place where the horses, cows or other animals are +stabled or kept by impervious walls without doors, windows or other +openings. + +12. No person suffering from an infectious disease, which can be +transmitted through ice-cream, shall work in an ice-cream manufacturing +plant. + +13. All workroom employees shall be clean in person at all times and +shall wear clean washable clothing and caps. They shall not smoke or +chew tobacco while at work. They shall not touch the product with +their hands at any time. Employees may be specially designated to cut +and wrap brick ice cream and to fill fancy moulds and as this work +necessitates some handling of the product, such employees must be +scrupulously clean and wear clean, washable clothing and caps. + +14. All wagons, trucks, drays, cans and tubs, platforms and racks, +shall be so constructed that they may readily be cleaned and they shall +be kept clean. Utensils must be of smooth non-absorbent material, as +tin, or tinned copper, the seams of which are flushed smooth with +solder. + +15. Suitable means or appliances shall be provided for the proper +cleansing or sterilizing of freezers, vats, cans, mixing cans or +tanks, piping and all utensils used as containers for ice-cream or +raw material, and all tools used in making or the direct handling of +ice-cream, and all such apparatus, utensils, and tools after use shall +be thoroughly cleansed and scalded with boiling water or sterilized +with steam. The water supply for washing utensils must be free from +contamination. + +16. No person shall use any vessel used in the manufacture and sale of +ice-cream for any other purpose. + +17. Soft or melted ice cream or any other ice-cream shall not be +refrozen under any circumstances. + +18. Milk and cream must be stored only in clean receptacles in clean +refrigerators. Milk or cream which has undergone various fermentations, +gaseous, bitter or otherwise, shall not be used in the manufacture of +ice-cream. Flavoring extracts, condiments, syrups, fruits, nuts and +other materials used as food must be securely protected from dust, +dirt, vermin, flies and other contamination, and must be kept and +stored only in clean receptacles. Decomposed, decayed, fermented or +rancid food material shall not be used. Ice-cream must be stored only +in clean receptacles in clean refrigerators. + +19. It is expressly declared that the object of this code is to +insure a pure and clean product, made, stored and handled under clean +conditions, and no technical defect in the construction of any clause +shall relieve any person of the obligation of complying with the letter +and spirit of this code in its entirety. + +20. All creamery and condensery operators, ice-cream manufacturers and +all other dealers in milk and cream, and their customers must cleanse +all receptacles used in shipping milk and cream as soon as they are +emptied, when same are to be returned by railroad, trolley, or boat, in +order to prevent the development of dangerous bacteria to threaten the +health of the consumers of the product. + + +_Sanitary code of the association of ice-cream manufacturers of New +York state._ + +1. All factories or shops shall be open to the public at all times. + +2. Workrooms must be thoroughly clean and shall be well ventilated +and well lighted to the end that there shall be no dark or concealed +corners where rubbish or dirt may accumulate. + +3. The side-walls and ceilings of all workrooms shall be well plastered +or tiled or ceiled with metal. If plastered or ceiled with metal, they +shall be kept well painted with oil paint to the end that they may +readily be cleaned and they shall be kept clean at all times. + +4. The floors of all workrooms shall be impermeable and be made of +cement, tile laid in cement, or of other suitable non-absorbent +material which can be flushed and washed clean with water. Floors shall +be sloped to one or more drains which must be properly connected with +the sewerage system. + +5. Storerooms for materials shall be kept clean and free from +objectional odors. + +6. Doors, windows and other openings of every workroom shall be +screened during the fly season, and all workrooms and storerooms shall +be kept free from flies at all seasons of the year. + +7. All factories or shops shall have convenient toilet rooms separate +and apart from the workrooms, and no toilet room shall be within or +connected directly with a workroom either by a door, window or other +opening. The floors of the toilet rooms shall be of cement, tile or +other non-absorbent material, and shall be kept clean at all times. +Toilet rooms shall be furnished with separate ventilating flues or +pipes, discharging into soil pipes or on the outside of the building +in which they are situated. Lavatories and washrooms shall be adjacent +to toilet rooms and shall be supplied with soap, running water and +clean towels, and shall be maintained in a sanitary condition. Workroom +employees beginning work and after visiting toilet room shall wash +their hands and arms thoroughly in clean water. + +8. No person shall be allowed to live or sleep in any building used +as a factory or shop, unless the factory or shop is separated by +impervious walls, without doors or windows or other openings from the +parts of the building used for living or sleeping purposes. + +9. No horses, cows or other animals shall be stabled or kept in any +building where ice-cream is made, unless the factory or shop is +separated from the places where the horses, cows or other animals are +stabled or kept by impenetrable walls without doors, windows or other +openings. + +10. No person suffering from an infectious disease, which can be +transmitted through ice-cream, shall be employed in an ice-cream +manufacturing plant. + +11. All workroom employees shall be clean in person at all times and +shall wear clean, washable clothing and caps. They shall not smoke +or chew tobacco while at work. They shall not touch the product with +their hands at any time. Employees may be specially designated to cut +and wrap brick ice-cream and to fill fancy molds, and as this work +necessitates some handling of the product, such employees must be +scrupulously clean, and wear clean, washable clothing and caps. + +12. All wagons, truck, drays, cans and tubs, platforms and racks shall +be so constructed that they may be readily cleaned, and they shall be +kept clean. + +13. Suitable means or appliances shall be provided for the proper +cleansing or sterilizing of freezers, vats, mixing cans or tanks, +piping and all utensils used as containers for ice-cream, and all +tools used in making or the direct handling of ice-cream, and all such +apparatus, utensils and tools after use shall be thoroughly cleansed +and rinsed with boiling water or sterilized with live steam. + +14. Vessels used in the manufacture and sale of ice-cream shall not be +employed for any other purpose by any person. + +15. No member shall take back any broken package of ice-cream, nor any +unbroken package which contains soft or melted ice-cream. No ice-cream +shall under any circumstances be melted and refrozen. + +16. It is expressly declared that the object of this Code is to insure +a clean product, made, stored and handled under cleanly conditions, and +no technical defect in the construction of any clause shall relieve any +member of the obligation of complying with the letter and the spirit of +this Code in its entirety. + + + + +CHAPTER XVII + +_HISTORY AND EXTENT OF THE INDUSTRY_ + + +The history of the development of the ice-cream industry is only +fragmentary. This may be because the industry has developed very +gradually. Exact figures showing the size of the industry are lacking, +no authentic figures ever having been brought together. The facts +relating to the history of the industry have been gathered and very +well put together by F. M. Buzzell, in an article in the “Ice-cream +Trade Journal,” Vol. 5, No. 3. The history as given here is a copy of +the above article. + + +=222. Early history.=--“From motives of comfort and health, the +instinct of man in all ages and climates has been to maintain his +physical (if not his mental) being at a temperature as nearly normal +as possible. Thus we find the natives of Iceland and other very cold +climates living upon heat-producing foods, fats, tallow candles, and +such delicacies, while the South Sea Islander lunches on a little fruit +or cereal, or other food producing a minimum of bodily heat. This rule +applies also to liquid refreshment. Hot weather creates a demand for +cooling drinks, and vice versa. And we, in our day, when we sit in +the coolest spot to be found on some sweltering August night, and sip +our favorite cold drink, are actuated by the same motive which has +influenced our ancestors from the more recent past back to the days of +Job and Solomon the Wise. For the Bible tells us indirectly that the +people of Palestine knew and appreciated the refreshing quality of snow +in time of harvest. The Jews, the ancient Greeks and Romans were all +accustomed to the use of snow for cooling wines and other beverages, +and it is to-day used in this way in certain parts of Spain and Turkey. + +“Only those southern localities which were favored with the proximity +of snow-capped mountains could enjoy the luxury of a snow-cooled +beverage or dessert. Where snow is not obtainable, liquids were, and +still are, cooled in porous jars, and urns exposed to cool breezes, +or, in lack of a breeze, swung about to create a current of air. The +principle is a familiar one. The most common method of preserving snow +was to saturate it with water, having packed it closely into some +receptacle, of considerable size probably, and allowing it to freeze +into a kind of porous ice, from which blocks could be cut as required +for use. To chill a dessert or a liquid, the dish containing it was +imbedded in a larger vessel partly filled with snow and particles of +ice, and the open space closely packed with it. It was then allowed to +stand until it had become as cold as possible or as desired. + +“Alexander the Great is said to have been very fond of iced beverages, +and one of our modern varieties, the Macedoine, it is said, was named +for the great Macedonian. Snow and ice were used at the table in the +court of Henry III of France in the hot summer months. The Italians, +it is claimed, made the first improvement in the original method of +cooling, which improvement was to dissolve saltpetre in water and +pour a little of the solution in with the snow and ice surrounding +the dish to be cooled. Later, it was found that better results were +attained by dropping the saltpetre directly into the snow and ice, and +at the same time revolving the vessel containing the substance to be +chilled. By this means the mixture in the vessel could be brought to a +fairly solid state. Wines were commonly iced in this way, then water, +sweetened and flavored with various juices or other flavorings, was +made into a sort of water ice. Water ices and such refreshments are +still the rule in the Orient, while ice-cream, as we know it, is rare. + +“There is no reliable record of the first water ices. Dates and places +are either lacking altogether in the vague allusions made to them or +are so indefinite as to be of no value. It is probable that they were +brought to France from Italy by Catherine de Medici, who preferring +cookery to which she was accustomed, brought her staff of cooks with +her. The date is given as about 1550. Water ices are said to have been +made by Contreaux, an Italian who established a famous café in Paris. +Lemonade was invented about 1630: to whom the credit belongs is not +known. From water ices to mixtures containing milk or cream and eggs, +was apparently a logical progression, but history is vague on the +question of who first made ice-cream.” + + +=223. Development of ice-cream in the household.=--“It is recorded +that in Rome, a certain Quintus Maximus Gurges, nicknamed ‘The +Glutton,’ a well known writer of those times on subjects pertaining to +the table wrote a recipe in one of his books for a dish that somewhat +resembled ice-cream. The name ice-cream is one of modern origin, the +original terms being butter ice, or cream ice, the latter being to-day +favored in England. The earlier forms, after the ices containing milk +or cream, which were really the first ice-creams known, were called +butter ice probably because of their rich butter-like consistency, +being made from rich cream and spaddled. Cream ice is said to have been +known in Paris in 1774. Recipes for water ices and milk ices, it is +claimed, were brought from Asia by Marco Polo, who visited Japan in the +fifteenth century. Cream ice is mentioned in an account of a banquet +given by Charles I, of England. The dish was made by a French cook +named De Mireo, and it is related that the king was so well pleased +with the ‘frozen milk,’ as he called it, that he pensioned the cook +with twenty pounds a year on condition that he would not divulge the +secret of making the dessert, nor make it for anyone but him. Another +account says that the first ice-cream was set before the Duc de +Chartres on a hot day in August, 1774, by his chef, who had depicted +the duke’s coat-of-arms on the cream. Again we find in an account of an +entertainment given by Louis XIV, of France, that ‘toward the end of +the feast, his chef caused to be placed before each guest, in silver +gilt cup, what was apparently a freshly laid egg, colored like those of +Easter, but, before the company had time to recover from their surprise +at such a novelty at dessert, they discovered that the supposed eggs +were a delicious sweetmeat, cold, and compact as marble.’ It is also +claimed that a certain Carlo Gatti first introduced cream ices into +England. + +“A French cook, Clermont, residing in London, gave instructions for +making sweet ices in a book he published in 1776. English cook books +one hundred and fifty years old give recipes for cream ices in which +cream and milk, sugar, eggs, arrowroot or flour and flavoring were +used. Recipes have always varied according to the whim or desire of the +maker, and there is no similarity in the amounts of cream or milk to be +used. + +“It is a question whether Germany or England first made ice-cream, but +it is generally conceded that the Germans led the English in making +fancy moulded creams. + +“We deduce from the foregoing bits of narrative that ice-cream was not +apparently discovered, but rather was the result of a slow process +of evolution or development, which was taking place in different +localities at about the same time. History states that ice-cream +was first sold in New York by a Mr. Hall, at 75 Chatham street, now +Park Row. Ice-cream is mentioned in an account of a ball given by a +Mrs. Johnson, December 12, 1789, and was introduced to the city of +Washington by Mrs. Alexander Hamilton at a dinner at which President +Jackson was present. She had become familiar with the dish in New York. +The first advertisement of ice-cream appeared in a New York paper, +the _Post Boy_, dated June 8, 1786, and reads as follows: ‘Ladies and +gentlemen may be supplied with ice-cream every day at the City Tavern +by their humble servant, Joseph Crowe.’ A negro, one Jackson who had +worked at the White House in Washington after Mrs. Hamilton introduced +ice-cream to President Jackson, learned the recipe and started a +confectionery. He sold his cream readily at one dollar per quart. +Others imitated him, but Jackson held his custom and prospered by +making the best goods and died wealthy.” + + +=224. Development of wholesale ice-cream.=--“Jacob Fussell is admitted +to be the father of the wholesale ice-cream business. The year 1851 +found him in the milk business at Baltimore. His supply of milk came +into Baltimore on the Northern Central Railway from York county, Pa. +A few of his customers wanted cream, and finding that satisfactory +results were not obtained by ordering cream intermittently to supply +an unsteady demand, he made arrangements for a regular shipment. +Here again a difficulty presented itself, for at times he found +his stock of cream accumulating, which must be disposed of in the +best way possible. To utilize this surplus he conceived the idea of +making ice-cream, the retail price of which at this time by the few +confectioners who sold it was sixty cents per quart. The idea proved +an inspiration, for the ice-cream business soon overshadowed the milk +business, which was in time disposed of. Mr. Fussell believed in the +value of printers’ ink and advertised his new business, and then, +as now, intelligent advertising paid. Devoting his entire attention +to the ice-cream business, he prospered in it, and built up a large +business, the success of which has continued through three generations +to the present day. In 1852 and 1853 he tried out a scheme for making +his ice-cream at the source of supply of his raw material, rather than +at the distributing point, but it did not prove successful, for while +the ice-cream was actually produced cheaper in the country, the fact +that his own attention was divided between the two establishments, and +that the stock at the selling end could not be readily controlled, +counteracted the lesser manufacturing cost, and the result was that the +project was abandoned and not repeated. In 1856 the Baltimore business +was left with a partner and a factory was opened in Washington, D. C. +In 1862 Boston was added to the chain of plants. Here a large exporting +firm, who had made considerable money shipping ice to London, India, +and Brazil, saw a new outlet for ice in the ice-cream business. They +attempted to induce Mr. Fussell to go to Brazil and start a factory +there, and offered to back him with the necessary capital if he wanted +it, but he was not interested. Failing to get him to send one of his +men over, they arranged for one of their own men to learn the art of +making ice-cream, and paid a modest $500 for the formula. How the South +American venture fared is not recorded. In 1864 the New York house +of Fussell was started and continued with the usual success. Here +the prevailing price among confectioners was $1.25 per quart. A Mr. +Brazleton, of Iowa, a friend of Mr. Fussell, losing his fortune in the +panic of 1857, came to Washington and learned the ice-cream business. +He went back west and opened a factory in St. Louis, later going to +Cincinnati and Chicago. + +“American enterprise was not long in taking up the new industry, +and the growth of the business had commenced. However, the real +development, the day of large figures in the business, had its +beginning not over fifteen years ago. The brine or refrigerating system +of freezing ice-cream has been efficiently applied only within the past +five years, and has now only fairly begun. + +“The first real progress toward artificial refrigeration is said to +have been made by a German in 1867, and it was then used only in +breweries, and to a very limited extent. Ice making by artificial means +came next. The use of refrigerating processes for making ice-cream +was probably begun in a way by chance, for large ice manufacturing +establishments put on an ice-cream department to utilize the broken or +waste ice, and the possibility of applying mechanical refrigeration to +the making of ice-cream was no doubt thus discovered. + +“Ice-cream is not today, as in past years, a luxury. Its lowered cost +brings it within reach of the masses: no longer is it something which +may be enjoyed only by the rich. It is fairly entitled to a place +in the class of necessities. Ice-cream is in high favor in England, +where the climate favors its use the year through. And it is used by +nearly all steamship lines, especially those making long trips in warm +climates. The passengers, who do not relish the indifferent quality +of most foreign made goods, demand American ice-cream. Every express +steamer of the North German Lloyd Line leaves New York with not only +a supply to care for the wants of its own passengers, but enough to +furnish the Japanese, Chinese, and Australian service of the company. +For the far eastern service the cream is carried in refrigerated +compartments to Bremerhaven and there transferred to ships sailing for +ports in India, China, Japan and Australia. + +“It does not seem proper to close this paper without some allusion to +our friend of the lawn party, ice-cream wagon, and county fair--the +ice-cream cone. I have heard that it was introduced in this country +at the St. Louis exposition. I have found directions for preparing a +refreshment called ‘fried ice-cream,’ sometimes known as ‘Alaska pie,’ +or ‘Alaska fritters.’ The method is, briefly to dip a cube of hard +ice-cream into a thin fritter batter and then plunge it into very hot +lard or olive oil. The pastry forms a good protector from the heat +and hardens so quickly that the cream is not softened in the least. +Another more elaborate form is said to be served in certain New York +cafés today. The fried ice-cream was introduced at the World’s Fair +in Chicago in 1893. It occurred to me that these freak varieties may +have suggested the idea of the ice-cream sandwich and ice-cream cone. +Whatever the origin, we will have to admit that the cone has sold many +a gallon of ice-cream and made many a dollar for those engaged in the +business. + +“And I believe that the future historian of this business, who shall +recount the progress of its development during the years from 1900 to +1910, cannot but remark upon that decade as being epoch making in the +annals of the trade.” + + +=225. Extent of the industry.=--While no census figures of the +industry have ever been assembled, careful estimates and surveys +have been made by both T. D. Cutler of the “Ice-Cream Trade Journal” +and L. O. Thayer of the “International Confectioner.” The results of +these surveys are shown in Table XVI. In comparison to the value of +ice-cream, the 1910 census gives the following values for the year +1909, for butter, cheese, and condensed milk; value of all dairy +products, $596,413,463.00; value of butter, cheese, and condensed milk +made in factories, $274,557,718.00; total investment in equipment, +$71,283,624.00. Regarding the distribution of the wholesale plants in +the United States, the North Atlantic states have the most, with the +Middle West a close second. The production of ice-cream in the South is +growing very rapidly. This is possible because of the homogenizers and +emulsifiers and mechanical refrigeration. + +TABLE XVI + +Production and Value of Ice-cream in the United States + + _Year_ _1911_ _1912_ _1913_ + Made by retailers, gallons 25,000,000 30,000,000 35,000,000 + Made by wholesalers, „ 113,000,000 124,000,000 137,380,000 + Total gallons made 138,000,000 154,000,000 172,380,000 + Average retail price per + gallon $1.40 $1.40 $1.40 + Average wholesale price + per gallon 80c 77c 80c + Total paid by consumer at + $1.40 per gallon $193,200,000 215,600,000 241,332,000 + Investment in wholesale + plants in dollars 50,000,000 60,000,000 68,000,000 + Persons employed: + Rush season + Yearly + + _Year_ _1914_ _1915_ _1916_ + Made by retailers, gallons 31,190,000 35,767,690 40,059,800 + Made by wholesalers, „ 132,571,000 139,682,400 168,260,000 + Total gallons made 163,761,000 175,550,090 208,319,800 + Average retail price per + gallon $1.50 $1.40 $1.40 + Average wholesale price + per gallon 80c 80c 82c + Total paid by consumer at + $1.40 per gallon 229,265,400 245,770,000 291,646,600 + Investment in wholesale + plants in dollars 73,500,000 78,200,000 83,600,000 + Persons employed: + Rush season + Yearly + + _Year_ _1917_ _1918_ + Made by retailers, gallons 41,133,000 38,243,000 + Made by wholesalers, „ 178,252,000 192,810,000 + Total gallons made 219,385,000 231,053,000 + Average retail price per + gallon $1.60 $1.65 + Average wholesale price + per gallon 92c $1.04 + Total paid by consumer at + $1.40 per gallon 307,139,000 381,237,450 + Investment in wholesale + plants in dollars 93,450,000 96,050,000 + Persons employed: + Rush season 40,000 + Yearly 20,000 + + + + +INDEX + + + Acid-coagulating group, 175 + Acid-forming group, 175 + Acid test, 200 + Adulterated ice-cream, 4 + Advertising, 255 + Alexander, Jerome, 248 + Ammonia machines, 116 + Audels, 101 + Automobile truck, 251 + Available refrigeration, 110 + Ayres, S. H., 11, 21 + Ayres, S. H., and Johnson, W. T., Jr., 175 + + Babcock test, 183-197 + cream, 192 + laws, 266 + modifications of, 197 + skim-milk, 196 + whole milk, 183 + Bacilli, colon, 181 + Bacteria, 15, 170 + acid-coagulating group, 175 + acid-forming group, 175 + alkali group, 178 + conditions for growth, 16 + effect of temperature, 20 + forms of, 16 + freezing and hardening, 174 + inert group, 177 + number of, 171 + peptonizing group, 179 + prevention of growth, 18 + sources of, 170 + total acid group, 175 + types of, 175 + utensils, 174 + Bacteriology, problems of, 181 + study of, 181 + Baer, A. C., 139, 163 + “Batch,” 129 + Baumé scale, 27 + Benkendorf, G. H., 213 + Benkendorf test, 213 + Binders, 51 + effect of, 167 + Bisque ice-cream, 73 + Boiled milk test, 203 + Brainard, W. K., 167 + Brick-cutting machine, 159 + Brick molds, 159 + Bricks, 145 + Brine box, 148 + freezer, 84 + tanks, 119 + British thermal unit, 101 + Bookkeeping, 258 + Bowen, John T., 101, 107, 111 + Butter, 41 + Butter testing for fat, 205 + moisture, 205 + salt, 207 + Buying materials, 257 + Buzzell, F. M., 287 + + Cabinet, 253 + Can washers, 95 + Caramel ice-cream, 72 + Carpenter, M. R., 151 + Census figures, 295 + Chocolate and cocoa, 46 + adulteration of, 49 + composition of, 48 + manufacture of, 47 + standard for, 48 + Chocolate ice-cream, 72 + Chocolate sirup, 49 + Clarifier, 22 + Cleanliness, 278-280 + Clemner, P. W., 21 + Coffee ice-cream, 72 + Colloids, 249 + Color, 132 + Composition, 249 + Compressor, 117 + Condensed milk, 25 + marketing, 31 + method of manufacture, 25 + purchase of, 28 + standard for, 27 + Condenser, 27 + Condensing coils, 117 + Condensory, 28 + amount of milk necessary, 29 + capital necessary, 31 + condition of milk, 30 + location, 31 + supply of milk for, 29 + supply of water for, 29 + Cook, L. B., 21 + Cooked ice-cream, 70, 74 + Cooling milk and cream, 18 + methods of, 19 + Cooper, Madison, 101 + Corbett, L. C., 104 + Corn sirup, 45 + Corn starch, 55, 70, 76, 77, 169 + Coumarin, 64 + Cow, food for, 13 + health of, 14 + Cream, composition of, 23 + emulsified, 41 + homogenized, 41 + standard for, 24 + Creamers, 95 + Crystallization, 167 + Custards, 76 + Cutler, T. D., 295 + + Dairy products, legal standards, 267-271 + Defects, 165 + appearance, 169 + body and texture, 166 + Defects, flavor, 165 + package, 169 + richness, 169 + Defrosting the coils, 151 + air blast system, 154 + cold brine drip system, 153 + Cooper system, 151 + hot brine system, 154 + hot gas system, 155 + warm liquid system, 155 + Delivery, cost of, 252 + method of, 250 + packages used, 252-254 + Disc-freezer, 89 + Disease, 250 + Dishes, 254 + + Eggs, 55 + Ekenberg Co., 39 + Ekenberg process, 39 + Ellenberger, H. B., 139, 172, 175 + Emery Thompson freezer, 87 + Emulsors, 95, 141 + advantage of, 99 + Emulsified milk and cream, 10, 13 + English plum pudding, 76 + Equipment, 81 + cost of, 100 + Evaporated milk, 25 + Evaporating coils, 118 + Expansion valve, 118 + + Factory, construction, 272 + floors, 278 + light, 276 + location of, 272 + plans, 273-275 + ventilation, 277 + Fat, churned, 166 + Fillers, 51 + starchy, 55 + Flavors, 2 + Flavoring extracts, 57 + Food value, 247-250 + Formaldehyde test, 203 + Formulas, 45, 71 + Fort Atkinson freezer, 88 + Frandsen, J. H., 45 + Frandsen, J. H., and Markham, E. A., 69, 163 + Freezers, 81 + brine, 84 + disc, 89 + Emery Thompson, 87 + Fort Atkinson, 88 + hand, 83 + Perfection, 85 + Progress, 86 + tub and can, 83 + Freezing process, 134 + effect of sugar on, 137 + proper method of, 137 + purpose of, 134 + rate of, 134, 137 + Fruit, 132 + extracts, 68 + ice-cream, 73 + pudding, 76 + Fussell, Jacob, 291 + + Gelatine, 52, 132, 168 + food value, 249 + kettle, 53, 91 + preparation of, 53 + tests for, 52 + Gum tragacanth, 132 + Guthrie, E. S., and Ross, H. E., 204 + + Hammar, B. W., 172, 173, 174 + Hammar, B. W., and Goss, E. F., 172 + Hand freezer, 83 + Hardening, 91, 145 + effect on quality, 157 + forced-air, 149 + gravity-air, 149 + ice and salt box, 146 + method of, 145 + time required, 157 + Hardening-room, 149 + still-air, 149 + Heat, sensible, 102 + latent, 102 + specific, 102 + History, 287-289 + Holdaway, C. W., and R. R. Reynolds, 167, 215 + Homogenizers, 95, 141, 167 + advantage, of 99 + Homogenized milk and cream, 10, 13 + Horses and wagons, 251 + Hot well, 26 + Hunziker, O. F., 183 + + Ice, amount needed, 107 + field, 103 + saw, 106 + storing and harvesting, 105 + Ice and salt mixture, 107 + amount used, 148 + Ice-cream, appearance, 164 + bacterial count, 164 + body and texture, 164 + classification of, 69 + color, 2, 73, 132 + composition of, 249 + definition of, 2 + demand for, 12, 246 + desired standard, 5 + factory development, 291 + fancy molded, 158 + Federal standard, 2 + flavor, 164 + household development, 289 + ideal standard, 5 + materials used, 1 + package, 164 + poison, 250 + richness, 164 + standards, 267-271 + trowels, 158 + when removed from freezer, 134 + Ice-cream-making, a science, 6 + problems, 6 + Ice-cream mixers, 88 + Ice-cream powders, 55 + Ice-cream receipts, 45, 71 + bisque, 73 + caramel, 72 + chocolate, 72 + coffee, 72 + custards, 76 + fruit, 73 + ices, 78 + lacto, 80 + maple, 72 + milk sherbets, 80 + mousse, 73 + nut, 73 + parfait, 74 + puddings, 75 + punches, 79 + vanilla, 71 + water sherbets, 78 + Ice crushers, 93 + Ice-house, 104 + Iceland moss, 55 + Ice plow, 106 + Ices, 70, 78 + freezing, 144 + Ice shovel, 94 + Ice spud, 94 + Irish moss, 55 + + Joseph Burnett Extract Co., 57 + Judging and defects, 163 + + Keeping quality, 167 + + Lacto, 71, 80 + Lactometer, 198 + Board of Health, 199 + Quevenne, 199 + Laws, 264-271 + Lee, C. C., Hepburn, N. W., and Barnhart, F. M., 204 + Legal standards, 267-271 + Lemon extract, 65 + adulteration of, 66 + standard for, 65 + Lemon oil, chemistry of, 66 + preparation of, 65 + License, 266 + Loading platform, 276 + Losses, 262 + + Machinery, quality of, 81 + Manhattan pudding, 76 + Maple ice-cream, 72 + Marketing, 246 + Market, location of, 250 + McInerney, T. J., 18, 174 + Mechanical refrigeration, 111 + absorption system, 116, 122, 124, 126 + compression system, 116 + cost of operating, 121 + direct expansion system, 118 + evaporating coils, 119 + materials used in, 113 + operating, 120 + parts of, 117 + principles of, 111 + Merrell-Soule Co., 34 + Merrell-Soule process, 35 + Michigan Agricultural Law, 15 + Milk and cream, absorption of odors, 14 + acidity of, 11 + adulterated, 264 + “aged,” 12 + bacteria in, 15 + contamination, 21 + neutralization of, 11 + proper care of, 22 + purchase of, 24 + quality of, 11, 13 + Milk, composition of, 23 + standard for, 24 + Milk powder, 33 + standards for, 33 + Milk powder in ice-cream, 37, 40 + Milk products, supply of, 8 + method of securing, 9 + Milk sherbets, 80 + Milk, used, 8 + Misbranded ice-cream, 5 + Mix, 129 + financial viewpoint, 130 + step in preparation of, 131 + temperature of, 133 + Mixers, 88 + Mojonnier tester, 218-240 + Mojonnier over-run tester, 240 + Molds, 15 + brick, 159 + center, 161 + individual, 161 + Mortensen, M., 69, 139, 142, 143, 158, 163 + Mousse, 73 + + National Association of Ice-cream Manufacturers, 3 + Nesselrode pudding, 75 + New Jersey Agricultural Law, 15 + Nut ice-cream, 73 + Nuts, 50 + + Oil traps, 117 + Orange extract, 65, 67 + Orange extract, adulteration of, 68 + standard for, 67 + Organisms, disease, 11 + Over-run, 134, 139 + controlling, 242 + factors effecting, 139 + to obtain, 143 + Over-run tester, 213, 240 + + Pack-cans, 91, 145 + Packing tubs, 262 + Parfait, 74 + Pasteurization, 11, 140, 172 + Peptonizing bacteria, 179 + Perfection freezer, 85 + Plans of factory, 273-275 + Powdered milk processes, 34 + “Price Current,” 258 + Price of dairy products, 258 + Progress freezer, 86 + Ptomaine poison, 250 + Pudding, 75 + English plum, 76 + fruit, 76 + Manhattan, 76 + Nesselrode, 75 + Punches, 70, 79 + + Refrigeration, 101 + terms used, 101 + Rennet, 56 + Report blanks, 261 + Rice flour, 55 + Rose, Flora, 247 + Ross, H. E., 18, 23, 205 + Ross, H. E., Guthrie, E. S., Fisk, W. W., 208 + Ross, H. E., and McInerney, T. J., 183 + Ruche, H. A., 43 + + Salesmen, 257 + Sandwich machine, 254 + Sanitary codes, 280-286 + Score card, 163 + Sediment test, 17 + Sherbets, 70, 78, 80 + freezing, 144 + Shipping clerk, 260 + Skimmed milk, composition, 24 + standard for, 24 + Slush box, 148 + Smoothness, 167 + Soft ice-cream, 263 + Solids not fat, 200 + Sproule, W. H., 197 + Stabilizer, 2, 51, 95, 132 + Standard ice-cream, 4 + Standardization, 208-212 + Stocking, W. A., Jr., 19 + Sugar, 2, 43, 131, 173 + invert, 43, 46 + Sugar-saving substitutes, 45 + Swell, 134, 139 + + Test, acid, 200 + Babcock, 183 + Benkendorf, 213 + hardness, 215 + Mojonnier, 218-240 + viscosity, 208 + Testing, 183 + Thayer, L. O., 295 + Transfer ladles or scoops, 146 + Transferring, 263, + Troy, H. C., 183, 207 + Tub and can freezer, 83 + Tubs, 262 + + Urner Barry Co., 41 + Utensils, cleaning, 279 + + Vacuum pump, 27 + Vanilla beans, 59 + Vanilla beans, curing of, 59 + marketing, 59 + production of, 60 + Vanilla, chemistry of, 63 + Vanilla extract, 57 + adulteration of, 64 + ingredients of, 62 + Vanilla ice-cream, 71 + Vanilla plant, 58 + Vanillin, 63 + Viscosity, test for, 208 + Vogt refrigerating machine, 123 + + Washburn, R. M., 69, 138, 139, 142, 163 + Water sherbets, 78 + Wisconsin Agricultural Law, 15, 264 + + Yeasts, 15 + + + Printed in the United States of America. + + + + + Transcriber’s Notes + + + The text as used in this e-text is as printed in the source document. + Unless listed below, inconsistent spelling, hyphenation, punctuation, + capitalisation, spacing, etc. and errors in grammar and style have + been retained; the contents have not been changed or corrected unless + listed below, and may not reflect current standards or practices. + + Sorted lists and tables: irregularities in the sorting order have not + corrected. + + Differences in wording between the Table of Contents and the section + headings in the text, and between the List of Illustrations and the + illustration captions, have not been standardised. + + Depending on the hard- and software used to read this text and their + settings, not all elements may display as intended. + + Page 94, Fig. 30, The perfection ice-cream can-washer and sterilizer: + presumably perfection is the brand, and might have been capitalised. + + Page 179, Table XI, first column row Winter samples: there is no + integer printed before .17 in the source document, which is likely + erroneous (as shown by the value above). + + Page 268-271: several of the footnotes listed ([58], [64], [65], + [69], [70], [71], [74], [77], [78] and [79]) do not occur in the + table. + + + Changes made: + + Tables and illustrations were moved out of text paragraphs. Footnotes + have been moved to underneath the paragraph(s) where they are + referenced. Some illustrations have been rotated. + + The table on pages 268-270 and the associated footnotes have been + recombined into a single table and list of footnotes. Some tables + have been split, recombined or otherwise re-arranged in order to fit + the available width. + + Minor obvious typographical and punctuation errors were corrected + silently. + + Page xiii, Fig. 12: Verticle belt driven... changed to Vertical belt + driven.... + + Page xv, item 36: opening bracket deleted from ...Sharples Separator + Co. (West Chester.... + + Page 71: ...ice-cream manufacterers employ... changed to ...ice-cream + manufacturers employ.... + + Page 77, Receipt 2: ...of vanilla to taste... changed to ...of + vanilla or to taste... as elsewhere; Follow directions given for No. + 1 moved from ingredients list to directions. + + Page 173: Hammer reaches the following conclusions... changed to + Hammar reaches the following conclusions.... + + Page 179, Table XI, bottom row: .17 changed to 0.17 for consistency. + + Page 221: ...water cooled dessicator used... changed to ...water + cooled desiccator used.... + + Page 223: ...the cooling dessicators are kept... changed to ...the + cooling desiccators are kept.... + + Table after Page 244, heading column 16: ...keep sample in oven and + cooler in... changed to ...keep sample in oven and cooler...; row + Sweetened condensed milk, last column: 00 min. in oven... changed to + 90 min. in oven.... + + Page 266: ...to indentify it changed to ...to identify it. + + Page 267: Table[53] XV changed to Table XV[53]. + + Page 268-271: pages 269 and 270 (the list of footnotes) are, apart + from the final remark on page 269 (No reports gave standards for + powdered milk), identical and have been included once only. + + Index: entry Andels changed to Audels; Ruche, H. A. changed to Ruehe, + H. A. + +*** END OF THE PROJECT GUTENBERG EBOOK 77728 *** |