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A HANDBOOK FOR DAIRYMEN 
 
THE RELATION 
 
 OF 
 
 TEMPERATURE, HUMIDITY 
 AND PRESSURE 
 
 TO 
 
 DAIRY OPERATIONS 
 
 A HANDBOOK FOR DAIRYMEN 
 
 By 
 
 WALTER WrFISK, M.S. IN AGR. 
 
 Professor of Dairy Industry, New York State 
 College of Agriculture, Cornell University 
 
 FOXBORO, MASS. 
 THE FOXBORO CO., Inc. 
 
 Neponset Avenue 
 

 Copyright, 1922 
 By The Foxboro Co., Inc. 
 
 First Edition, July, 1922 
 
 THE UNIVERSITY PRESS, CAMBRIDGE, U. S. A. 
 
 JCI.A(I81323 
 
 m "5 iy22 
 
:? FOREWORD 
 
 ^ 'TT^HE object of this book is to provide authorita- 
 
 I tive and up-to-date information on the relation 
 of temperature, humidity and pressure to the 
 manufacture of dairy products. 
 
 Because of his professional standing and wide ex- 
 perience with every phase of the dairy industry, 
 Professor Walter W. Fisk, of Cornell University, 
 was asked to prepare the material. 
 
 Professor Fisk is in no way connected with The 
 Foxboro Co., Inc., and no restriction of any kind 
 was imposed upon him. He was at liberty to write 
 what he wished. Each branch of the dairy industry 
 has been analyzed from the standpoint of tempera- 
 ture, humidity and pressure, and discussed in the 
 light of the best practices of the most successful 
 dairymen. No theories that have not proved to be 
 commercially practical are presented. 
 
 The result is an unbiased, authoritative treatise 
 on some of the most significant phases of dairy 
 operation. 
 
 With the hope that we have contributed to dairy 
 improvement and progress this book is dedicated to 
 the dairy industry. 
 
 THE FOXBORO CO., INC. 
 
 July 1, 1922 
 
TABLE OF CONTENTS 
 
 Chapter Page 
 
 I. Introduction 1 
 
 II. Bacteriology 9 
 
 III. Butter Making 19 
 
 IV. Milk and Cream 26 
 
 V. Ice Cream 39 
 
 VI. Condensed and Evaporated Milk .... 48 
 
 VII. Milk Powder 56 
 
 VIII. Cheese 59 
 
 IX. Casein and Milk Sugar 65 
 
 X. The Power Plant 67 
 
CHAPTER I 
 
 INTRODUCTION 
 
 It is only recently that the importance of tempera- 
 ture, pressure and humidity in relation to milk 
 handling has been fully realized. Authorities are 
 now agreed that the successful manufacture, han- 
 dling and storage of milk and milk products of prime 
 quality depend upon the knowledge and the careful 
 regulation of these factors. Cleanliness is not to be 
 minimized, but it is taken for granted in this dis- 
 cussion that every right-thinking dairyman has the 
 welfare of his community enough at heart to use the 
 utmost care in keeping his plant clean and sanitary. 
 Our aim is to give to the manufacturer, superin- 
 tendent and operator certain suggestions regarding 
 the relation of temperature, humidity and pressure 
 to dairy operations, which will not only enable him 
 to raise the standard of his product and eliminate 
 needless wastes, but in the end will be of assistance 
 to the whole industry. 
 
 Temperature has two influences on dairy opera- 
 tions: it regulates the growth of micro-organisms, 
 and it has a physical effect on certain operations 
 and on the quality of the finished product. 
 
 The Influence of Temperature on the Growth of 
 Micro-Organisms . 
 Every dairyman knows that in milk and milk 
 products there are many micro-organisms : bacteria, 
 yeasts and molds. Because these are really tiny 
 plants, their growth depends upon a readily avail- 
 able food supply and proper temperature. Milk and 
 
2 A Handbook for Dairymen 
 
 milk products furnish their food, but high tempera- 
 ture will kill them and low temperature will retard 
 their growth. 
 
 Professor W. A. Stocking in an interesting ex- 
 periment shows the effect of temperature on the 
 development of bacteria in milk. A sample of milk 
 was thoroughly mixed and divided into six equal 
 parts. The six bottles were placed in water at dif- 
 ferent temperatures for twelve hours, at which time 
 the germ content of each lot was determined. The 
 bottles were then all placed together in a tempera- 
 ture of 70° F. and allowed to remain until they 
 curdled. As each sample curdled, the time was re- 
 corded. Results show what may happen easily in 
 milk which is allowed to stand overnight without 
 thorough cooling. 
 
 Effect of Different Temperatures, Maintained 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, 9300 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 
 
 In cheese and butter making, the growth of cer- 
 tain types of organisms, especially the lactic acid 
 type, is essential. In other dairy operations, such 
 as the handling of market or fluid milk, condensed 
 milk and evaporated milk, the growth of organisms 
 invariably causes the product to spoil. 
 
Introduction 
 
 All dairymen and milk producers probably make 
 use of these facts, and the most successful cool the 
 milk as soon as it is drawn from the cow. Regard- 
 less of how clean the milk may be produced, there is 
 certain to be some micro-organisms in it. Of course 
 some of these are beneficial and others are harmful, 
 but as the producer cannot distinguish between them, 
 the development of all should be retarded by cooling 
 and holding cold. 
 
 The Influence of Temperature on the Qutdity of the 
 Finished Product. 
 
 The quality of the finished product is judged by 
 its flavor, body, texture and appearance. 
 
 Flavor is affected by bacterial growth, and this 
 growth in turn is regulated by the temperature. A 
 high temperature will cause a bad or undesirable 
 flavor. A low temperature may cause a lack of 
 flavor. 
 
 The body and texture and appearance are deter- 
 mined by the moisture content and the process of 
 manufacture. Both are largely regulated by tem- 
 perature. For example, if cheese is heated too high, 
 it will be dry, hard and crumbly, while ice cream 
 that is not frozen sufficiently will be watery and 
 grainy. The churning of cream into butter depends 
 upon the correct churning temperature. If the 
 cream is too warm, the butter will be too soft and 
 will have a very poor body ; if too cold, it will not 
 churn at all, or very slowly. 
 
 The successful manufacturer must make a prod- 
 uct that is uniform from day to day. Uniformity 
 depends upon many factors, but the important one, 
 as will be pointed out in detail later, is that of the 
 correct temperature. 
 
A Handbook for Dairymen 
 
 The Inflitence of Temperature on the Storage of 
 Dairy Products. 
 
 The keeping quality of milk or milk products de- 
 pends largely upon a uniform holding temperature. 
 If the temperature is allowed to go too high or 
 to fluctuate from day to day, the product will not 
 keep as long as when held constantly at the proper 
 temperature. 
 
 When butter and cheese are held in a refrigerator 
 and the temperature rises, they not only deteriorate 
 in flavor and body and texture, but molds grow 
 rapidly and injure the quality. Bad flavors and 
 poor body and texture in practically all dairy prod- 
 ucts quickly develop under poor storage conditions. 
 
 Many losses can be positively attributed to im- 
 proper storage temperatures. For example : The 
 writer knows of one case in which an ice-cream 
 manufacturer lost his entire business because of 
 the poor quality of his ice cream. The ice cream 
 was of good quality when it left the freezer, but be- 
 came grainy and icy during the hardening process, 
 due to uneven and, at times, too high a temperature. 
 
 Another case of loss is that of the storage of 
 butter. A thousand tubs of butter were held in a 
 storage which occasionally became too warm and 
 damp so that molds rapidly grew. In this case, 
 each tub had to be stripped and the mold scraped 
 off. The butter sold at a loss of ten cents a pound, 
 or about six dollars a tub, because of the moldy 
 flavor. A loss of six thousand dollars could have 
 been avoided if only a very small fraction of that 
 sum had been invested in a recording thermometer. 
 
 There is no definite length of time that a product 
 may be held in storage without deteriorating. 
 Time of deterioration depends upon the quality of 
 the product when put in and the temperature of 
 
Introduction 
 
 storage. Whenever the temperature rises during 
 storage, if conditions are right, it gives the lactic 
 acid-forming bacteria a chance to develop. This is 
 especially true of fluid or liquid milk and unsweetened 
 condensed milk. These products sour quickly in a 
 refrigerator that is not held at a uniform cold 
 temperature. 
 
 The Influence of Humidity on Dairy Products. 
 
 Humidity is most important in the ripening of 
 cheese, the manufacture of milk powder and the 
 storage of products not hermetically sealed. The 
 correct humidity is necessary for the proper func- 
 tioning of the ripening agent during cheese curing. 
 If the humidity is too low, there will be too much 
 evaporation, which will cause unnecessary losses. If 
 too high and accompanied by the correct tempera- 
 ture, molds will grow and spoil the product. If the 
 humidity is too high, it is impossible to make good 
 milk powder after certain processes. 
 
 The Influence of Pressure on Dairy Products. 
 
 It is very necessary to have a constant steam 
 pressure for the successful operation of many ma- 
 chines. For example: the centrifugal separator. If 
 there is not sufficient steam pressure, the efficiency of 
 the machine is reduced. It is also important to have 
 different materials put through machines at a given 
 pressure. For example : ice cream mixed through 
 the homogenizer. If the pressure is reduced, the in- 
 tended results are not accomplished. The important 
 subject of power-plant efficiency will be discussed in 
 a separate chapter. 
 
 As stated above, the quality and salability of 
 dairy products depend upon a careful regulation of 
 temperature, pressure and humidity. Manufactur- 
 
6 A Handbook for Dairymen 
 
 ing and storage losses can be traced directly to a 
 lack of knowledge, or to inadequate means of 
 controlling these factors. Savings can be made in 
 formerly wasted materials, steam and water. Losses 
 can be turaed into profits. The vital relationship 
 of temperature, pressure and humidity to each dairy 
 product will be discussed in the following chapters. 
 
View of one of six temperature-control boards with recording 
 thermometers for incubation rooms in Pathological Division, Bureau 
 of Animal Industry, U. S. Dept. of Agriculture. Foxboro Ther- 
 mometers of the continuous seven-day type are used. 
 
CHAPTER II 
 
 BACTERIOLOGY 
 
 The control of temperature within close limits is 
 very important in laboratories where bacteriological 
 investigations of the micro-organisms of dairy prod- 
 ucts are conducted. In many instances the success 
 in the maintenance of cultures depends upon the 
 ability continuously to maintain a constant tem- 
 perature. 
 
 The micro-organisms of dairy products are grown 
 on various food materials known as media. To se- 
 cure the proper temperature for growth they are 
 usually placed in an insulated box known as an in- 
 cubator, and the temperature is regulated by an 
 electric thermostat, fan and ice. 
 
 Each incubator is usually fitted with a seven-day 
 recording thermometer. The recording elements are 
 mounted on the wall outside of the incubator and 
 the capillary tube passes through the wall, the bulb 
 being located near the top and in the center of the 
 incubator. The charts taken from the recorder are 
 examined and any variations in temperature be- 
 yond the prescribed limits are noted, with the time 
 at which the variations occurred. 
 
 The value of a continuous temperature record in 
 the process of incubating cultures lies in the fact 
 that such records not only show the temperature at 
 all times throughout the period of incubation, but 
 they are dated and can be filed for reference. It is 
 thus possible to determine with accuracy the tem- 
 perature maintained in the incubating process on 
 any previous date. 
 
10 A Handbook for Dairymen 
 
 If the temperature in the incubator is too low, 
 the growth of the organism will be very slow, or it 
 will not grow at all. Also if the temperature is too 
 high, the organism may not grow. In either case 
 if it does grow, it will not give a strong type and 
 contaminations are likely to appear. 
 
 Starter. 
 
 A practical application of bacteriology to dairy 
 operations is the preparation of starter.* The 
 lactic acid starter used in the making of butter and 
 cheese is the most common. Other starters are the 
 molds of Camembert and Roquefort cheese, Bulgari- 
 cus for Swiss cheese, the eye-forming culture for 
 Swiss cheese, and the starter for ripening cream for 
 Hebrew trade. 
 
 The Lactic Acid Starter. 
 
 Since cultures must be prepared by a bacteriolo- 
 gist, commercial laboratories have developed a large 
 business in their production, usually under trade- 
 marked names. Some of these cultures represent 
 races of lactic bacteria cultivated and cared for 
 efficiently, hence uniformly valuable over long 
 periods of time. Others, carelessly produced, are 
 worthless, or even a peril to the user. 
 
 The organisms are usually shipped in small 
 quantities in bottles of liquid or powder, or in cap- 
 sules of uniform size. The contents may be either 
 the culture medium upon which the organisms grew, 
 or an inert substance designed merely to hold the 
 bacteria in active form. In either solid or liquid 
 form, the producer of the culture should guarantee 
 its activity up to a plainly stated date. 
 
 •Starter 13 a culture of desired organisms in a living or active 
 state. 
 
Bacteriology 11 
 
 It is the problem of the cheese or butter maker 
 first to keep the organisms pure, and second to in- 
 crease them to such numbers and in such an active 
 condition that they are commercially useful. The 
 common practice is to allow them to develop in some 
 material, usually whole milk or skimmed milk, or 
 even dissolved milk powder. 
 
 The manufacturer's directions apply to average 
 conditions and must be varied to suit the individual 
 case. The directions should state the amount of 
 milk necessary for the first inoculation, usually one 
 or two quarts. 
 
 Suggestions for Selecting Starter Milk. 
 
 As the flavor of the starter will be the same as 
 that of the milk from which it is made, great care 
 should be used in its selection. The following sug- 
 gestions are offered to aid in this selection: only 
 clean-flavored sweet milk, free from undesirable 
 micro-organisms, should be used. Choose the morn- 
 ing milk because the bacteria have not had much 
 chance to develop. In no case should mixed milk be 
 used, as this eliminates all opportunity for selection. 
 Choose the milk from a producer who maintains 
 high standards and whose milk is usually in good 
 condition. The quality of the milk can be deter- 
 mined by the fermentation test. 
 
 Pasteurization. 
 
 Pasteurization kills most of the micro-organisms 
 in the milk and makes a clean seed-bed for the pure 
 culture. The temperature of pasteurization recom- 
 mended for starter making differs with the author- 
 ity. A temperature of 180° F. for thirty minutes or 
 longer seems to be very satisfactory because under 
 
12 A Handbook for Dairymen 
 
 these conditions nearly all the micro-organisms are 
 killed. 
 
 The small amount of milk needed for starter 
 making may be pasteurized by placing the container 
 in water heated to the desired temperature. A very 
 satisfactory arrangement is to cut off a barrel and 
 place a steam pipe in it. Two or three extra 
 bottles should be prepared, as some of them may be 
 broken. Fill the bottles about two-thirds full so 
 that there will be room enough for the mother 
 starter and for later examination. To avoid pos- 
 sible contamination, it is desirable not to have the 
 milk or starter touch the cover. It is a good plan 
 when pasteurizing to have one bottle of water as a 
 check. Test the temperature for all the bottles by 
 inserting a thermometer in the bottle filled with 
 water. Never put a thermometer in the starter 
 bottles. Uniform temperature may be obtained by 
 shaking. 
 
 Cleanliness. 
 
 A successful starter can only be made if all uten- 
 sils coming in contact with the milk are sterile. Keep 
 the covers on the containers at all times. Don't put 
 thermometers into the bottles. When examining the 
 starter, pour it out — never dip into it. If the 
 cover is removed from the container, put it in a 
 sterile place. It is easy to spoil the culture if the 
 cover becomes contaminated. 
 
 Glass fruit jars, or quart milk bottles, or tin 
 containers may be used for starter making. The 
 first two are more easily cleaned and their content is 
 always visible, but they break easily. The tin con- 
 tainer does not break, but it is hard to keep clean 
 and the chance for contamination is exceedingly 
 great. 
 
Bacteriology 13 
 
 Adding the Culture. 
 
 After being pasteurized, the milk should be cooled 
 to a temperature of 80° F. — a suitable temperature 
 for the development of the lactic acid-forming or- 
 ganisms. The commercial or pure culture is added 
 to the milk and mixed thoroughly by shaking the 
 bottle. The shaking should be repeated four or five 
 times every fifteen or twenty minutes. The milk 
 should be placed in a room or incubator with a tem- 
 perature as near 80° F. as possible. A uniform 
 temperature is necessary for the growth of the or- 
 ganisms. The bacteria in the pure culture are more 
 or less dormant, so that this higher temperature is 
 necessary to stimulate their activity. The milk 
 should be coagulated in eighteen to twenty-four 
 hours, depending largely on the uniformity of the 
 temperature maintained in the incubator. 
 
 "Mother" Starter, or Startolme. 
 
 The thickened sour milk obtained by inoculating 
 the sweet pasteurized milk with the pure culture of 
 lactic acid-forming bacteria is known as " Mother '* 
 starter, or Startoline. Its physical properties, odor 
 and taste should be examined carefully. 
 
 Sometimes the first few inoculations from a new 
 culture will show signs of gas, but ordinarily this 
 will quickly disappear and have no injurious effect 
 on the starter. It should have a clean sour-cream 
 odor and be smooth, thick and creamy, entirely free 
 from lumps, whey, and gas pockets. This starter 
 may have an objectionable flavor, due to the media 
 in which the organisms were growing when shipped. 
 In such cases it is necessary to carry one or two 
 propagatipns to overcome the flavor, to enliven the 
 micro-organisms %nd to secure the quantity desired. 
 
14 
 
 A Handbook for Dairymen 
 
 A Foxboro Recording Thermometer installed on the exterior 
 of a bacteriological cold storage vault. The tube connecting 
 the bulb passes through the wall. Permanent records of the 
 exact temperature are thus maintained and unnecessary open- 
 ing of the door to the vault is eliminated. 
 
 TJie Second Day's Propagation. 
 
 For the second day, the milk for the starter is 
 selected as on the first day. It is pasteurized, and 
 this time is cooled to 70° F. because the organisms 
 have become more active, and hence do not require so 
 high a temperature to grow. Instead of inocu- 
 lating with powder, as was done the first day, the 
 mother starter already prepared is thoroughly 
 mixed with the milk. Only a very small amount is 
 required, perhaps a tablespoonful to a quart bottle. 
 Since this starter may have the flavor of the media 
 used in the laboratory culture, it may be necessary 
 that it be carried one or two days more to eliminate 
 it. After the flavor has become normal, the mother 
 starter is ready for use. 
 
Bacteriology 1^ 
 
 Preparation of Larger Amou/nts of Starter. 
 
 Determine the quantity of starter required, select 
 the milk as carefully as before, pasteurize, cool and 
 add the mother starter. 
 
 The milk should be pasteurized at a temperature 
 of 180° F. for thirty minutes if possible. A good 
 incubation temperature is 60° to 65° F. However, 
 this temperature may be varied so that the starter 
 will be ready at a given time — the higher the tem- 
 perature the less time is required to ripen the 
 starter. 
 
 Pasteurization and incubation can be carried on 
 in a starter can or a milk can. The former requires 
 mechanical power to operate the agitator. The 
 latter may be used where mechanical power is not 
 available, and the milk and starter is stirred by 
 hand. This kind of apparatus is more often used 
 in cheese factories. 
 
 Amount of Mother Starter to Use. 
 
 Use the mother starter prepared the day before. 
 The amount depends upon the following factors : 
 
 1. Temperature of milk when mother starter is 
 added. 
 
 2. Average temperature at which the milk will be 
 kept during the ripening period. 
 
 3. Time allowed for the starter to ripen before it 
 is used. 
 
 4. Vigor and acidity of the mother starter added. 
 
 The amount of starter may vary from 0.5 per cent 
 to 10 per cent, depending upon the above conditions. 
 
 Some operators prefer to add the mother starter 
 while the milk is at a temperature of about 90° F., 
 before it has been cooled to the incubating tempera- 
 
16 A Handbook for Dairymen 
 
 ture. This reduces the amount of mother starter 
 necessary. 
 
 If an even incubating temperature can be main- 
 tained, less mother starter is needed than if the 
 temperature goes down. 
 
 If the ripening period is short, it will require a 
 larger amount of mother starter. If the starter has 
 a low acidity or weak body, indicating that the or- 
 ganisms are of low vitality, more will be required. 
 
 The starter, when ready for use, may or may not 
 be coagulated. A good idea of the quality of the 
 starter may be gained by the condition of the 
 coagulation. It should be jelly- or custard-like, close 
 and smooth, entirely free from gas pockets, and 
 should not be wheyed off. 
 
 When broken up, the starter should be of a smooth, 
 creamy texture and entirely free from lumpiness or 
 wateriness. It should have a slightly pronounced 
 acid aroma. The flavor should be clean, mildly acid 
 and free from all undesirable taste. 
 
 Bulgaricus Starter. 
 
 The Bacillus Bulgaricus Starter for Swiss cheese 
 is carried in about the same way as the lactic acid 
 starter, except that whey is a more desirable medium 
 than milk. This organism requires a temperature 
 of 100° F. for growth. 
 
 The growing of the molds for Camembert and 
 Roquefort cheese is somewhat similar, except that 
 Camembert is aerobic and grows on the outside of the 
 cheese, while the Roquefort is anaerobic and grows 
 on the inside of the cheese. The Camembert mold 
 may be grown on a media of whey agar or on sterile 
 crackers. It grows spores more rapidly when held 
 at a temperature of 60° to 70° F. It should also be 
 kept very moist. The Roquefort molds grow best 
 
Bacteriology 17 
 
 when inoculated into a fresh loaf of bread that has 
 been paraffined as it comes from the oven. As soon 
 as cooled, it is ready for inoculation. This can be 
 done by drawing the mold spores with sterile water 
 into a sterile pipette and then forcing them into the 
 bread. The loaf should be sealed and held at a 
 temperature of 60° to 70° F. 
 
 Experiments are now being conducted on the eye- 
 forming culture for Swiss cheese. The fact is known 
 that such a culture exists, but definite information is 
 lacking as to its preparation and handling. 
 
 Com/mercial Buttermilk. 
 
 Commercial buttermilk is the term applied to 
 lactic acid starter used for drinking. It is often 
 sold as buttermilk or prepared buttermilk, and 
 under many trade names, such as Lactic Culture, 
 Bulgazoon and the like. It is made in the same way 
 as any starter up to the time it begins to coagulate. 
 As soon as it is coagulated and before the coagula- 
 tion becomes too hard it must be broken up. If 
 allowed to become too hard, the buttermilk will be 
 lumpy and will whey off very rapidly — a great ob- 
 jection to it. As soon as coagulated the starter 
 should be churned. The flavor is improved if 10 
 or 15 per cent of sweet whole milk is added and 
 churned with the starter. As soon as churned, it 
 should be placed in a ripener or other suitable con- 
 tainer and rapidly cooled to 40°— 50° F. and held 
 at this temperature. If allowed to warm up and 
 cool again, it will whey off much more rapidly. As 
 soon as cooled it is ready for consumption. It may 
 be sold in bulk in 40-quart cans or put up in various- 
 sized milk bottles. Commercial buttermilk should 
 have a desirable mild acid flavor, a smooth, creamy 
 body and texture, and should not have free whey. 
 
CHAPTER III 
 
 BUTTER MAKING 
 
 The a B C's of butter making are separating the 
 cream from the milk, preparing the cream for churn- 
 ing or ripening, churning, packing and storing; 
 five simple steps full of pitfalls for the unwary. 
 What are the precautions to be taken ? How can 
 losses be avoided ? How can savings be made by the 
 proper regulation of temperature and pressure? 
 After studying the manufacturing methods of many 
 of the most successful butter makers of the country, 
 a few of the factors which enable the butter maker 
 to manufacture consistently a uniform product of 
 high quality will be set forth. 
 
 Separating the Cream. 
 
 If the cream separator is working efficiently there 
 should not be more than .01 to .02 per cent of fat 
 left in the skimmed milk. The efficiency of the ma- 
 chine depends upon the following factors : 
 
 1. Temperature of milk being separated. If the 
 separator is set up properly, temperature is the 
 factor which is most likely to affect the ef- 
 ficiency of the machine. If the temperature is 
 below 85°-100° F. the separator will not re- 
 move all the fat. 
 
 2. Speed of the separator. If belt driven, keep 
 the belt tight. If turbine driven, the proper 
 speed can be insured by placing a pressure 
 gauge in the steam line. It must be remem- 
 bered that if the separator is not operated at 
 the specified speed, it will not skim clean. 
 
 3. Rate of flow of milk. Operate the separator to 
 
20 A Handbook for Dairymen 
 
 capacity and keep the feed cup filled to the 
 level indicated by the maker. 
 
 4. Percentage of fat in the cream. Sometimes a 
 cream rich in fat will not be skimmed clean. 
 Butter makers differ as to the desirable fat con- 
 tent but a cream testing 30—35 per cent fat will 
 give satisfactory results. The separator will 
 not always deliver cream containing exactly the 
 same percentage of fat, even if the cream screw 
 is adjusted properly. If an exact percentage of 
 fat is desired, it can only be secured by stand- 
 ardizing, (For method of standardizing, see 
 page 31.) 
 
 5. Amovmt of slime in bowl. 
 
 Most butter makers install a pre-heater to heat 
 the milk to the proper separating temperature. It 
 is desirable to connect a recording thermometer to 
 the pre-heater. This gives the operator an accurate 
 working guide and the management a check on 
 operating conditions. 
 
 Pasteurization. 
 
 There is no " best practice " in regard to pasteur- 
 ization. There are pro-pasteurizers and those who 
 are against it. Those that favor pasteurization 
 base their judgment on the fact that it eliminates 
 the possibility of disease and that it usually im- 
 proves the flavor of the butter. A temperature of 
 145° F. for thirty minutes has proved to be very 
 satisfactory. However, if cream is pasteurized at 
 too high a temperature, the butter is likely to have 
 a cooked flavor. After pasteurization the cream 
 should be cooled to the ripening temperature of 60° 
 to 75° F. 
 
 Preparing the Cream for Churning — Ripening. 
 
 Good judgment of the butter maker and the taste 
 of the consumer usually determine the method of 
 
Butter Making 21 
 
 preparing the cream for churning. The various 
 methods of preparation are as follows : 
 
 1. The cream may be pasteurized, if sweet, held 
 cold and churned sweet. 
 
 2. Pasteurized, starter added and churned. 
 
 3. Neutralized and not pasteurized, starter added 
 and churned. 
 
 4. Neutralized, pasteurized, starter added and 
 churned. 
 
 Sweet cream should be pasteurized before churn- 
 ing, or there will be a large fat loss in the but- 
 ter-milk. Cream that is churned sweet makes a 
 milder-flavored butter and keeps better in storage. 
 
 Amount of Starter. 
 
 No definite rule can be stated as to the amount of 
 starter to add, as it will vary from 1 to 30 per cent. 
 The proper amount depends upon the length of time 
 the cream is ripened, the ripening temperature, the 
 acidity of the starter and the acidity desired in the 
 cream at the time of churning. The amount of acid 
 or degree of ripeness is determined largely by the 
 amount of fat in the cream. The more fat the less 
 acid is required. The cream when ready to churn 
 should have 0.3 to 0.65 per cent acidity. 
 
 There is no definite time when the starter is 
 added. Some butter makers prefer to add it when 
 the cream is partially cooled, usually from 75° to 
 90° F. The cream must be cooled below the tem- 
 perature at which the lactic acid organisms are 
 killed before the starter is added or its effect will be 
 lost. Others prefer to add it after the cream is 
 partially cooled. Lumps of starter cause white 
 specks in the butter. Therefore, the starter should 
 be strained. 
 
22 A Haiidhook for Dairymen 
 
 After being ripened the cream should be cooled to 
 the churning temperature or slightly below and held 
 for at least three or four hours. This allows the 
 fat globules to congeal. 
 
 It is obvious that successful ripening and pas- 
 teurization hinge upon the careful regulation and 
 control of temperature while the cream is in the coil- 
 ripening vat. Even the experienced operator should 
 have an accurate guide at this critical stage. Re- 
 gardless of the size of the creamery, it has been 
 proved that the installation of a recording ther- 
 mometer not only helps to standardize the quality 
 of the product, but points \he way to savings worth 
 many times the cost of the instrument. 
 
 Churning. 
 
 If the butter is to be colored, it is desirable to add 
 the coloring to the cream either just before or im- 
 mediately after placing the cream in the churn. Some 
 makers prefer to add the color to the salt. However, 
 it is difficult to obtain a uniform color by this method. 
 The amount of color to use varies from 1 to 3 ounces 
 per 100 pounds of fat. 
 
 Churning time is determined by the temperature 
 of the cream. The churning temperature varies 
 from 48° to 65° F. according to the season of the 
 year, being lower in summer than in winter. If 
 churned too warm, the butter will come very quickly 
 and will be too soft. If too cold, it will come very 
 slowly and the granules will not gather easily. The 
 butter should be churned until the granules are 
 about the size of kernels of wheat. This should 
 require thirty to sixty minutes. 
 
 After the buttermilk is drawn off, the butter 
 should be washed with water at the same temperature 
 as the buttermilk. If the butter is very soft, colder 
 
Butter Making 23 
 
 water may be used to make it firm. It is advisable 
 to wash the butter in two waters to remove any re- 
 maining buttermilk. The churn should be given 
 several revolutions in each water. 
 
 Butter may be marketed either with or without 
 salt. That without salt is known as sweet butter, 
 and is demanded especially by the Hebrew trade. 
 The amount of salt to add varies from 1.5 to 5 per 
 cent, depending upon the taste of the consumer. It 
 is advisable to add the salt while the butter is yet 
 in the granular condition. 
 
 Working distributes the salt evenly, presses out the 
 free buttermilk, gives the butter a solid body, the 
 desired texture or grain and a uniform color, and 
 also incorporates the moisture. If worked too much 
 the butter will be greasy or salvy and the texture 
 injured. If not worked enough, the color will not 
 be uniform and the body will not be solid. 
 
 The increase of the butter over the butter fat is 
 due to the incorporation of moisture and is known 
 as over-run. It is the aim of every butter maker to 
 secure as large an over-run as possible. The legal 
 limit of moisture is 15.99 per cent. 
 
 The incorporation of the moisture should be 
 studied in relation to the following factors : 
 
 Temperature of cream and wash water. 
 Amount of cream in churn. 
 Percentage of fat in cream. 
 Amount of working. 
 Pasteurized or raw cream. 
 Degree of ripeness of cream. 
 Churning butter in wash water. 
 Working butter in wash water. 
 
 The secret of moisture control lies in regulating 
 the churning temperature and in adjusting the 
 
24 A Handbook for Dairymen 
 
 working process according to the firmness of the 
 butter as determined by the chemical, physical and 
 mechanical properties of the butter fat, and in the 
 constant use of a reliable moisture test. This shows 
 the vital relation of temperature to over-run. In 
 many plants the cost of manufacture, marketing and 
 profits must come from the over-run because the 
 fat is paid for at the same price per pound as the 
 butter. 
 
 As a large percentage of butter is made during 
 the short season when there is a large production 
 of milk, it has to be held to supply the demand 
 during the rest of the year. Quality is maintained 
 by storing the butter in very cold refrigerators — 
 0° F. or below. If the quality of the butter is to 
 be maintained, the temperature of the refrigerator 
 must not fluctuate. The refrigerator should be 
 equipped with a recording thermometer with the re- 
 cording element located on the outside. This saves 
 opening the door to observe the temperature, and 
 also gives a record of the temperature. It is es- 
 pecially desirable if butter is stored for some one 
 else. Then, if it deteriorates in storage, the oper- 
 ator can produce his records of the temperature, 
 which at once show whether the deterioration is due 
 to temperature or to some other cause. The value 
 of such an installation was pointed out in Chapter I. 
 
 Whey Butter. 
 
 Whey, or the liquid portion of the milk left after 
 cheese making, contains a small amount of fat. The 
 amount varies with the variety of cheese made, 
 usually from .8 to .3 per cent. Special separators 
 have been devised to separate this fat from the whey. 
 Cream rich in fat (60 to 75 per cent) is desirable. 
 
Butter Making 25 
 
 This cream should be reduced with milk to the cor- 
 rect percentage for churning. It may be made into 
 butter the same as any cream. It is best to pasteur- 
 ize it and add a larger percentage of starter. Be- 
 cause the whey naturally contains the softer fats, 
 whey butter is apt to be soft-bodied. For this 
 reason, it should be churned at as low a temperature 
 as possible. If the milk from which the whey is 
 obtained was of good quality, the cream separated 
 as soon as the whey was drawn and the directions 
 above followed, whey butter should be of good 
 quality. 
 
CHAPTER IV 
 
 MILK AND CREAM 
 
 It has been estimated that the total annual produc- 
 tion of milk in the United States is valued at 
 approximately two billion dollars. Of this huge 
 amount 45.7 per cent is consumed as fluid or whole 
 milk. In brief, these figures show the tremendous 
 importance of this one branch of the dairy industry. 
 
 Market milk not only is of importance from the 
 standpoint of its production value, but it has be- 
 come a vital factor in the life and well-being of 
 every community. Boards of Health in a great 
 many localities enforce stringent regulations in re- 
 gard to the source of the milk supply and the 
 pasteurization of the milk. But progressive dairy- 
 men exercise greater care than is even prescribed by 
 the Boards of Health. 
 
 In the last analysis the successful handling of 
 market milk depends upon the careful regulation of 
 temperature. The growth of bacteria, pasteuriza- 
 tion, storage and the efficient operation of the plant 
 are all influenced by temperature. The dairyman 
 knows that temperature influences these processes, 
 but is that knowledge accurate and is it used to 
 make his business more profitable? As one superin- 
 tendent of a large Boston dairy said: "Until I kept 
 a record of temperatures, a careless employee, in the 
 Pasteurizing Department alone, could waste his 
 wages in steam and water several times a day." 
 
 Pre-H eating and Clarifying. 
 
 As the milk is delivered to the dairy at a lower 
 temperature than is required for proper handling 
 
Milk and Cream 
 
 27 
 
 View of the pre-heater and clarifier at the Turner Centre 
 System, Somerville, Mass. The Foxboro Long Distance 
 Dial Type Indicating Thermometer inserted is commonly 
 used on pre-heaters. 
 
 (often 40° F, in winter time) a pre-heater is usually 
 necessary. The heating may be accomplished by 
 running the cold milk counter-current to hot water, 
 or by other methods. A temperature of 85° to 
 100° F. has proved satisfactory for the subsequent 
 process of clarifying. It is almost necessary to in- 
 stall a recording thermometer on the pre-heater in 
 order to save heat and to prevent the milk from 
 scorching. 
 
 The centrifugal clarifier strains the milk at any 
 temperature, but works more efficiently when the 
 milk is heated 85° to 100° F. The clarifier removes 
 the dirt, pus cells, blood corpuscles, etc., without 
 separating the whole milk and aerates the milk, 
 which improves its flavor. The machine may be belt 
 or turbine driven, and if the latter a pressure reg- 
 ulator in the steam line will insure a uniform pres- 
 sure. The clarifier will not operate efficiently unless 
 it is run at the prescribed speed. 
 
28 
 
 A Handbook for Dairymen 
 
 Pasteurization. 
 
 There are two general methods of pasteurization, 
 — the Holding and the Flash methods. A more 
 recent development is the pasteurization of the milk 
 after it has been bottled. However, this method is 
 not used so generally as the first two. 
 
 The Flash Method: The milk or cream is heated 
 to a temperature of 170° to 180° F. for an instant, 
 and then cooled. Unless great care is exercised the 
 high temperature is likely to impart a cooked flavor 
 to the product. 
 
 The Holding Method: The milk is heated to a 
 temperature of 142° to 145° F. and held at this 
 temperature for thirty minutes. 
 
 Bottle Method : 
 After the milk is 
 packaged, it is placed in a large 
 container and heated by live 
 steam. Although the application 
 is different, the principle of pas- 
 teurization is the same as has been 
 described above. The bottles are 
 cooled by running cold water into 
 the container. It is claimed that 
 this method of pasteurization is 
 more efficient because there is little 
 or no chance for the milk to be 
 contaminated. 
 
 Pasteurization is the critical 
 stage in the handling of market 
 milk. Temperatures in the pas- 
 teurizer should be known and care- 
 fully regulated at all times. Even the most experi- 
 enced operator cannot be so efficient or so vigilant 
 as a recording thermometer or a temperature con- 
 
 Special Foxboro 
 bulb and fitting for 
 the Bottle Method 
 of Pasteurizing. 
 
Milk and Cream 
 
 29 
 
 Installation of Foxljoro Uccurding Thermometers on Burrell 
 continuous pasteurizer at the Turner Centre System, Somer- 
 ville, Mass. The arrows indicate the location of the ther- 
 mometer bulbs. 
 
 troller-recorder. The only way a superintendent can 
 check the efficiency of his plant is to keep a record 
 of the operations involving temperature. The regu- 
 lations set down by most Boards of Health require 
 that a record be kept each day showing the tempera- 
 ture at which the cream or milk is heated and the 
 time it was held at this temperature. 
 
 Three thousand dollars were saved the first year 
 by one medium-sized dairy after four recording 
 thermometers and two temperature controllers were 
 installed in the Pasteurizing Department. The in- 
 stallation paid for itself during the first two weeks 
 of operation. 
 
 Cooling 
 
 After pasteurization, the milk should be cooled 
 rapidly with as little contamination as possible, to a 
 
30 A Handbook for Dairymen 
 
 Installation of Foxboro Recording Thermometers on coolers 
 at the Turner Centre System, Somerville, Mass. Arrows show 
 where thermometer bulbs are connected to the coolers. 
 
 temperature of about 40° F. At this temperature 
 the growth of any organisms which may have sur- 
 vived pasteurization is very slow. The ease of clean- 
 ing the cooling device should not be overlooked. 
 The milk may be cooled by running it counter-cur- 
 rent to cold water, or by other equally effective 
 methods. A recording thermometer should be used 
 as a check on the efficiency of the cooler. 
 
 The milk is often held in large glass-lined holding 
 tanks until it can be packaged. The tanks are 
 equipped with brine pipes for cooling and an agitator 
 to keep the cream evenly distributed throughout the 
 milk. The operator will find a recording ther- 
 mometer a great aid in maintaining a uniform cool 
 temperature in the tanks. If the milk or cream 
 warms up, it is very likely to sour. 
 
 As it is customary to prepare the milk and cream 
 
Milk and Cream 31 
 
 one day and to deliver it the next, it is necessary to 
 refrigerate the milk for several hours. The refrig- 
 erator temperature should be held uniformly at 
 40° F. and the milk should not be allowed to freeze. 
 Here, too, the only practical precaution for the 
 dairyman is a recording thermometer. With the 
 recording elements on the outside of the refrigerator, 
 the temperature may be observed and maintained 
 uniformly without the loss otherwise incurred by 
 frequent opening of the door for temperature 
 observation. 
 
 Standardizing Milk and Cream. 
 
 To satisfy the consumer, cream or milk containing 
 the same percentage of fat should be sold every day. 
 Because a separator will not deliver cream testing 
 the same percentage of fat every day the cream must 
 be standardized. 
 
 Standardizing milk or cream consists of raising 
 or lowering the fat content to a fixed standard. 
 
 In standardization, there are two classes of prob- 
 lems involved: first, a certain fixed amount of milk 
 is to be made up or a certain amount of standardized 
 milk is desired. Second, 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 scheme 
 has been devised that is simple. 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 percentage of fat in 
 
J2 
 
 A Handbook for Dairymen 
 
 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. Sub- 
 tract the smaller number on the left-hand corner 
 from the number in the center and place the re- 
 mainder 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 ma- 
 terial required. If these two numbers are added, 
 they will express the number of pounds of the mix- 
 ture, 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 cor- 
 responds in fat test to the number on the left-hand 
 corner directly opposite. 
 
 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 following 
 result is obtained: 
 
 This means that if 2 pounds of 40 per cent cream 
 are mixed with 35 pounds of 3 per cent milk, tlie re- 
 
Milk and Cream 
 
 33 
 
 suit 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. 
 
 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 500 pounds of 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. 
 
34 A Handbook for Dairymen 
 
 This problem may also be worked by simple pro- 
 portion : 
 
 1 : 25 : : X : 500 
 
 25x = 1 X 500 
 
 25x = 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. — Ansmer. 
 
 The number of pounds of 3 per cent milk can be 
 found directly by simple proportion: 
 
 24 : 25 : : X : 500 
 
 25x = 24 X 500 = 12,000 
 
 X = 480, number of pounds of 3 per cent 
 
 milk. — Answer. 
 
 Proof. 
 
 In working problems in standardization, it is al- 
 ways wise to prove the answer and check for mis- 
 takes. 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 X .04 = 20). According to the results the 
 480 pounds of 3 per cent milk would contain 14.4 
 pounds of fat (480 X .03 = 14.4). The 20 pounds 
 of 28 per cent cream would contain 5.6 pounds of 
 fat (20 X .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 is made 
 
Milk and Cream 
 
 35 
 
 up furnish the 20 pounds of fat, the answer is 
 correct. 
 
 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. 
 
 Foxboro Automatic Temperature Recorder-Controller in- 
 stalled on a flash pasteurizer at Schlosser Bros. Creamery, 
 Plymouth, Indiana. This one instrument does the work of 
 both controller and recorder. The chart shown is a facsimile 
 of an actual chart from this instrument. The heavy lines 
 show how close the temperature was held within the allow- 
 able limits. The momentary high and low temperatures 
 were caused by the cream supply being changed from one 
 fore-warmer to another. 
 
36 A Handbook for Dairymen 
 
 Working the problem by the rectangle method 
 (see page 32), 1 part of 28 per cent cream is re- 
 quired for 24) parts of 3 per cent milk. According 
 to the terms of the problems, 150 pounds of 28 per 
 cent cream must be used, and the 3 per cent milk 
 must be increased 150 times. This would give 150 
 pounds of 28 per cent cream (IX 150), and 3600 
 pounds of 3 per cent (150X24=3600), making 
 in all 3750 pounds (150 + 3600 = 3750) of a 4 per 
 cent mixture. 
 
 This problem may also be worked by simple pro- 
 portion : 
 
 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 X .04 = 150). If the 150 
 pounds of 28 per cent cream and 3600 pounds of 
 3 per cent milk furnished 150 pounds of fat, the 
 problem is correct. 
 
 3600 X .03 = 108, number of pounds of fat 
 in milk. 
 
 150 X .28 = 42, number of pounds of fat in 
 cream. 
 
 108 -|- 42 = 150, number of pounds of fat in 
 mixture. — Answer. 
 
Milk and Cream 
 
 37 
 
 Specific Gravity and Weight of Milk and Cream 
 at a Temperature of 68° F. 
 
 
 Per cent of fat 
 
 Specific 
 gravity 
 
 Weight of 
 one gallon 
 in pounds 
 
 Skim 
 
 .025 
 
 3 
 
 3.5 
 
 4 
 
 5 
 
 6 
 
 10 
 15 
 18 
 20 
 22 
 25 
 28 
 30 
 32 
 35 
 38 
 40 
 
 1.037 
 1.034 
 1.033 
 1.032 
 1.031 
 1.030 
 1.025 
 1.018 
 1.015 
 1.013 
 1.011 
 1.008 
 1.006 
 1.004 
 1.002 
 .999 
 .997 
 .995 
 
 8.6295 
 
 Milk 
 
 8.6045 
 
 Milk 
 
 8.5962 
 
 Milk 
 
 8.5879 
 
 Milk 
 
 8.5796 
 
 Milk 
 
 8.571S 
 
 Mixed Milk, Cream . . . 
 Mixed Milk, Cream . . . 
 Cream 
 
 8.5297 
 8.4714 
 8.4564 
 
 Cream 
 
 8.4298 
 
 Cream 
 
 8.4132 
 
 Cream 
 
 8.3882 
 
 Cream 
 
 8.3715 
 
 Cream 
 
 8.3549 
 
 
 8.3383 
 
 Cream 
 
 8.3133 
 
 Cream 
 
 8.2966 
 
 Cream 
 
 8.2800 
 
 
 
CHAPTER V 
 
 ICE CREAM 
 
 No milk product varies so much in quality as ice 
 cream. This is largely due to the fact that the 
 federal standard which requires that a vanilla mix- 
 ture contain 14 per cent of fat and a fruit or nut 
 mixture 12 per cent is not enforced. In many 
 states ice cream may be sold either very low or very 
 high both in fat and in milk solids not fat depend- 
 ing upon the amount the manufacturer wishes to 
 spend for materials. Many concerns make an ice 
 cream containing 8 to 10 per cent of fat and 
 30 to 35 per cent of total solids. 
 
 The common milk products used in ice cream are 
 cream, whole milk, skimmed milk, whole or skimmed 
 condensed milk, whole or skimmed powdered milk and 
 butter. 
 
 The Importance of Refrigeration. 
 
 One of the most essential parts of an ice-cream 
 plant is its refrigerator. Because the demand for 
 ice cream fluctuates with weather conditions, manu- 
 facturers must carry a sufficient amount of raw 
 materials to meet any emergency. These raw prod- 
 ucts should be kept in a refrigerator at a uniform 
 temperature and as near freezing as possible — but 
 not frozen. Without such a refrigerator manufac- 
 turers either run short of raw materials and cannot 
 supply a sudden demand that would mean a large 
 increase in profits, or certain of the raw products 
 spoil before they are manufactured. Sour ice cream 
 
40 A Handbook for Dairymen 
 
 is more often due to faulty refrigeration of raw 
 materials than to anything else. 
 
 Many ice-cream plants have a fruit storage room. 
 This is similar to the storage for raw-milk products 
 and in many cases is a small refrigerator partitioned 
 off from the larger one. Fruits should never be 
 allowed to freeze. 
 
 Pasteurization of Milk Products. 
 
 Some manufacturers pasteurize their milk prod- 
 ucts while others do not — there is no uniform 
 practice. It is a known fact that pasteurization 
 reduces the viscosity, so that after being pasteur- 
 ized the product must be held for some time to 
 regain its viscosity. As will be pointed out later, 
 the viscosity is very important in relation to swell. 
 Products should be pasteurized at as low a tempera- 
 ture as possible, not above 145° F., to prevent a 
 cooked flavor. Any of the milk or cream pasteur- 
 izers may be used. 
 
 Basic Recipes for Ice Cream. 
 
 Here are two basic recipes which make ten gallons 
 of ice cream : 
 
 No. 1. Without condensed milk. 
 40 lbs. cream. 4 oz. gelatine in 4 lbs. water. 
 
 8 lbs. sugar. Flavoring. 
 
 The percentage of fat in the cream governs the 
 percentage of fat in the ice cream. 
 
 No. 2. With condensed milk. 
 30 lbs. cream. 4 oz. gelatine in 
 
 10 lbs. condensed milk. 4 lbs. of water. 
 
 7 lbs. sugar. Flavoring. 
 
 Either whole or skimmed condensed milk may be 
 used. Plain condensed is preferable to sweetened 
 
Ice Cream 41 
 
 condensed milk. Again, the percentage of fat in the 
 cream may be varied to give the ice cream the de- 
 sired percentage of fat. 
 
 For standardization see page 31. The percen- 
 tage of fat in the mix is figured by dividing the total 
 pounds of fat by the total weight of the materials 
 in the mix. (The " mix " is the unfrozen ice cream.) 
 
 Milk powder is either used to make milk or to 
 bring up the percentage of milk solids not fats or 
 in place of the condensed milk, or the cream or milk 
 may be made by mixing the various milk products 
 mentioned above. 
 
 Machines for Mixing Materials. 
 
 The mixing process can be accomplished by two 
 types of machines. One is the type in which the 
 materials are forced through very small holes or 
 slots by centrifugal force. It is known as an emulsi- 
 fier. The other, in which the material is forced be- 
 tween a valve and its seat by a piston pump, or 
 through a very small opening between porcelain 
 discs by a piston pump, is known as a viscolizer and 
 homogenizer. Viscolizers and homogenizers are 
 much more powerful than the emulsifiers and break 
 up the fat globules so finely that the cream can 
 never be rechurned. Many ice-cream makers run the 
 whole mix through these machines, which increases 
 the viscosity which in turn increases the swell. 
 
 Mixing. 
 
 Opinions differ as to the correct temperature at 
 which the materials should be emulsified. Some 
 manufacturers prefer to pasteurize and then emul- 
 sify at the same temperature. A temperature of 
 120° to 130° F. is satisfactory. The materials 
 must be kept thoroughly mixed or else the fat 
 rapidly separates and comes to the top. This mix- 
 
42 A Handbook for Dairymen 
 
 ing may be accomplished by supplying the machine 
 with the materials from a revolving coil or by an 
 agitator in the supply tank. When butter is used, 
 it should be cut into small pieces and then melted 
 in the milk or water. 
 
 Directly from the emulsifier, the material must be 
 cooled as near 40° F. as possible, or the fat may 
 separate. 
 
 The preparation of materials to be viscolized or 
 homogenized is the same as stated above. By means 
 of an adjusting screw, the pressure under which the 
 material passes through the machine can be regu- 
 lated. The pressure may vary from 2000 to 3000 
 pounds. The only objection to these machines is 
 that inferior products can be made to appear better 
 than they really are. This is especially true of but- 
 ter. Homogenizers may also be used on market or 
 fluid cream, causing it to appear much richer than 
 it really is. 
 
 The next step in the preparation of the mix is 
 the adding of the correct amount of sugar. If an 
 ice-cream powder is used it must be thoroughly mixed 
 with the sugar. Gelatine is added to prevent the 
 separation of water crystals that cause ice cream 
 to be grainy or icy. There are several ways to 
 prepare the gelatine. The following method gives 
 good results : To eight quarts of cold water add one 
 pound of gelatine, or in that ratio, then mix the 
 gelatine and water and let it stand twenty or thirty 
 minutes. In this length of time the gelatine and 
 water mixture will be rather thick. It should then 
 be heated in a water bath to 165°-170° F. While 
 at this temperature it should be added slowly to the 
 mix which is being agitated. The whole mix or 
 each individual freezer can now be flavored. 
 
Ice Cream 
 
 43 
 
 Showing Properties of Solution of Salt (Siebly)* 
 {Chloride of Sodium) 
 
 Per cent Pounds salt Degrees or Weight Specific , 
 
 of salt per gallon salometcr per gallon gravity j 
 
 by weight , of solution ' 60° F. at39°F. at39°F..4°C. 
 
 Freezing 
 Specific point 
 heat I F. 
 
 1 
 
 0.084 
 
 4 
 
 8.40 
 
 1.007 
 
 0.992 
 
 30.5 
 
 2 
 
 0.169 
 
 8 
 
 8.46 
 
 1.015 
 
 0.984 
 
 29.5 
 
 2.5 
 
 0.212 
 
 10 
 
 8.50 
 
 1.019 
 
 0.980 
 
 28.6 
 
 3 
 
 0.256 
 
 12 
 
 8.53 
 
 1.023 
 
 0.976 
 
 27.8 
 
 3.5 
 
 0.300 
 
 14 
 
 8.56 
 
 1.026 
 
 0.972 
 
 27.1 
 
 4 
 
 0.344 
 
 16 
 
 8.59 
 
 1.030 
 
 0.968 
 
 26.6 
 
 5 
 
 0.433 
 
 20 
 
 8.65 
 
 1.037 
 
 0.960 
 
 25.2 
 
 6 
 
 0.523 
 
 24 
 
 8.72 
 
 1.045 
 
 0.946 
 
 23.9 
 
 7 
 
 0.617 
 
 28 
 
 8.78 
 
 1.053 
 
 0.932 
 
 22.5 
 
 8 
 
 0.708 
 
 32 
 
 8.85 
 
 1.061 
 
 0.919 
 
 21.2 
 
 9 
 
 0.802 
 
 ' 36 
 
 8.91 
 
 1.068 
 
 0.905 
 
 19.9 
 
 10 
 
 0.897 
 
 40 
 
 8.97 
 
 1.076 
 
 0.892 
 
 18.7 
 
 12 
 
 1.092 
 
 48 
 
 9.10 
 
 1.091 
 
 0.874 
 
 16.0 
 
 15 
 
 1.389 
 
 60 
 
 9.26 
 
 1.115 
 
 0.855 
 
 12.2 
 
 20 
 
 1.928 
 
 80 
 
 9.64 
 
 1.155 
 
 0.829 
 
 6.1 
 
 24 
 
 2.376 
 
 96 
 
 9.90 
 
 1.187 
 
 0.795 
 
 1.2 
 
 25 
 
 2.488 
 
 100 
 
 9.97 
 
 1.196 
 
 0.783 
 
 0.5 
 
 26 
 
 2.610 
 
 104 
 
 10.04 
 
 1.204 
 
 0.771 
 
 —1.1 
 
 Properties of Solution of Chloride of Calcium {SieblyY 
 
 Per cent 
 by weight 
 
 Specific heat 
 
 Specific gravity 
 at 60° F. 
 
 Freezing point 
 in degrees F. 
 
 1 
 
 0.996 
 
 1.009 
 
 SI 
 
 5 
 
 0.964 
 
 1.043 
 
 27.5 
 
 10 
 
 0.896 
 
 1.087 
 
 22 
 
 15 
 
 0.860 
 
 1.134 
 
 15 
 
 20 
 
 0.834 
 
 1.182 
 
 5 
 
 25 
 
 0.790 
 
 1.234 
 
 —8 
 
 ♦From Larsen & White's "Dairy Technology," by courtesy of the authors. 
 
 Ageing the Mix. 
 
 It is desirable, after the mix has been prepared, 
 to " age " it by allowing it to stand. Ageing blends 
 
44 
 
 A Handbook for Dairymen 
 
 View of hardening room at the Turner Centre System, Somer- 
 ville, Mass. It is very important that the temperature be kept 
 even if quality is to be maintained. 
 
 the flavors and increases the viscosity. It is usually 
 done in large, insulated brine circulating coil tanks, 
 equipped with recording thermometers. The one 
 great danger of ageing is that the mix is likely 
 to sour. Souring is determined entirely by tempera- 
 ture. If the mix sours, it is practically a loss. It 
 may be neutralized but it never makes a product of 
 as high a grade. If cream is aged and sours while age- 
 ing, it can be churned into butter, providing it has 
 not been homogenized. For this reason many man- 
 ufacturers prefer to age the cream rather than the 
 whole mix. 
 
 The temperature at which the mix enters the 
 freezer is an important factor in relation to both 
 quality and swell. The mix should enter the freezer 
 as near 40° F. as possible. This helps to eliminate 
 the danger of churning and of jDroducing an ice 
 cream of greasy texture. 
 
Ice Cream 45 
 
 How to Freeze Ice Cream. 
 
 The freezer has a dasher with scrapers revolving 
 in the center and a jacket around the outside in 
 which cold brine is circulated. The rate of flow of 
 the brine is determined by the pump, and after it is 
 once regulated should be constant. The temperature 
 of the brine may vary within wide ranges, though 
 the best results are obtained when it is from -\-Q° 
 to -f-10° F. Temperature is an extremely im- 
 portant factor in connection with the making of 
 ice cream. If the brine is too warm the cream will 
 churn instead of freeze, and there will be chunks 
 of butter in the ice cream. If the brine is too 
 cold, the ice cream freezes too fast and then it is 
 difficult, if not impossible, to obtain the swell. 
 
 Care in freezing is of the utmost importance be- 
 cause it affects both the quality of the ice cream and 
 the swell. If the desired swell is not obtained, the 
 business will be a failure. The rate or time to 
 freeze depends upon 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. 
 
 The first three factors show the important part 
 that temperature plays in the freezing process. It 
 should take from 12 to 20 minutes to freeze a 
 batch of good ice cream. 
 
 By " swell " is meant the increase in volume of 
 the ice cream over the mix. This increase is due to 
 the incorporation of the air. The factors affecting 
 swell may be divided into two general classes : kind 
 and preparation of materials used and method of 
 freezing. 
 
46 A Handbook for Dairymen 
 
 Certain combinations of these factors increase the 
 swell, while other combinations 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, age 
 until viscous. 
 
 4. The cream and milk or whole mix should be 
 homogenized or emulsified. 
 
 5. Condensed milk in the mix aids 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 sufficient supply of brine from 
 4-6° F. to 4-10° 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 to 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 de- 
 crease in the amount of swell. 
 
 If not enough swell is obtained in freezing, the 
 ice cream will be soggy and heavy, and if too much 
 swell is obtained the ice cream will be fluffy and 
 inclined to be grainy. A swell of 85 to 100 per 
 cent is satisfactory. 
 
 The Hardening Process. 
 
 When drawn from the freezer the ice cream is 
 in a semi-fluid condition and must be frozen solid 
 or "hardened." This is accomplished by placing 
 the cans of ice cream in a cold room known as a 
 hardening room or by packing them in ice and salt 
 or placing them in a box of cold brine. The usual 
 
Ice Cream 
 
 47 
 
 Foxboro Recording Thermometers for recording hardening 
 room temperatures at Schlosser Bros. Creamery, Plymouth, 
 Indiana. In this case the recorders are located at a considerable 
 distance from the hardening room, but there is no loss of ac- 
 curacy. 
 
 practice in the large plants is to have a hardening 
 room with a temperature of — 20° F. This will 
 harden the ice cream in twenty-four hours. In no case 
 should the temperature be allowed to go above 0° F. 
 A long-distance type recording thermometer shows 
 the temperature of the hardening room at all times 
 and saves loss of refrigeration due to the opening of 
 the doors to learn the temperature. It also gives the 
 engineer and the management a constant record. 
 Much ice cream properly made and of good quality 
 up to the time of hardening has been spoiled during 
 the hardening process, due to fluctuations in the tem- 
 perature. When the ice cream is allowed to melt and 
 freeze in the hardening room, its body and texture is 
 quickly ruined. It will become grainy and full of 
 ice crystals. After being hardened the ice cream 
 must be properly handled and packed in ice and salt 
 for delivery. 
 
CHAPTER VI 
 
 CONDENSED AND EVAPORATED MILK 
 
 Condensed milk is milk in which the solids have 
 been condensed by the removal of the water. This 
 is usually accomplislicd by boiling the milk in a 
 vacuum, although there are concentrators in which 
 a vacuum is not used. Either skimmed milk or whole 
 milk may be condensed, and may be made plain or 
 may be sweetened by the addition of cane sugar. 
 
 As a condensing plant usually receives milk much 
 faster than it can be condensed it is usually placed 
 in large holding .tanks. These tanks are insulated 
 and often refrigerated in order to keep the milk cold 
 and sweet. It is much easier to standardize the milk 
 in the holding tanks than it is the condensed milk 
 after it has been drawn from the pan. For method 
 of standardization see page 31. 
 
 The milk is first heated in large open copper ket- 
 tles, called fore-warmers or hot wells, in order that 
 cold milk will not be drawn into the vacuum pan. 
 When sweetened condensed milk is made, about 16 to 
 18 per cent of cane sugar is added to the milk in 
 the hot well. Sweetened milk is heated to 180°- 
 200° F. to dissolve the sugar, and the plain milk to 
 130°-150° F. 
 
 The boiling is done in a large copper container 
 called a pan. The size is spoken of in terms of the 
 diameter, i. e., a four-foot pan or a five-and-a-half- 
 foot pan. 
 
 The temperature is regulated by a steam jacket 
 on the bottom and several steam coils inside the 
 
Condensed and Evaporated Milk 49 
 
 pan. The temperature of the pan should be about 
 130° F. with a vacuum or about 25 to 26 inches of 
 mercury. 
 
 It is desirable to have the heating surface in the 
 pan as large as possible in order to make high steam 
 pressure in the jacket and coils unnecessary, and in- 
 sure complete condensation of the steam. Otherwise 
 too high milk temperatures or waste of steam results. 
 Steam gauges should be placed just after the valves 
 connecting the jacket and coils with the main steam 
 line. Twenty-five pounds' pressure is considered as 
 high as can be safely used, and many condenseries 
 operate with twelve to twenty pounds' steam pres- 
 sure. Taking into consideration the ordinary water 
 supply, fifteen pounds' steam pressure and twenty- 
 five inches' vacuum are about the best conditions that 
 can be steadily maintained. The temperature is 
 about 135 degrees at this vacuum. 
 
 The milk is drawn into tlie pan by vacuum. After 
 enough has been drawn in to boil well, a constant 
 stream maintains the same volume in the pan. Care 
 must be exercised or the milk Avill boil over the top. 
 The usual practice is to concentrate a trifle too much 
 and then standardize by the addition of distilled 
 water. This can only be done when the milk has 
 been standardized in the holding tanks. 
 
 It is very important for the successful operation 
 of the pan that it be equipped with an accurate 
 thermometer and vacuum gauge. A thermometer 
 which is constructed so that the bulb may be well 
 submerged in the milk is more sensitive to tempera- 
 ture changes and at the same time makes it possible 
 to place the indicator where it is convenient to read. 
 Such a thermometer is known as a long-distance type 
 thermometer. 
 
50 
 
 A Handbook for Dairymen 
 
 Boiling Points of Water at Different Vacua" 
 
 Absolute 
 
 pressure 
 
 per square inch 
 
 Vacuum inches 
 
 of mercury 
 
 column 
 
 Vacuum 
 millimeters of 1 
 mercury- 
 column 1 
 
 Temperatures of 
 
 boihng point of 
 
 water, F. 
 
 Temperatures of 
 
 boihng point of 
 
 water.C. 
 
 14.720 
 
 0.00 
 
 00 
 
 212.00 
 
 100.00 
 
 14.010 
 
 1.42 
 
 36 
 
 209.55 
 
 98.5 
 
 13.015 
 
 3.45 
 
 88 
 
 205.87 
 
 96.8 
 
 12.015 
 
 5.49 
 
 139 
 
 201.96 
 
 94.3 
 
 11.020 
 
 7.52 
 
 191 
 
 197.75 
 
 91.9 
 
 10.020 
 
 9.56 
 
 243 
 
 193.22 
 
 89.5 
 
 9.020 
 
 11.60 
 
 295 
 
 188.27 
 
 86.75 
 
 8.024 
 
 13.63 
 
 346 
 
 182.86 
 
 83.7 
 
 7.024 
 
 15.67 
 
 398 
 
 176.85 
 
 80.5 
 
 6.024 
 
 17.70 
 
 450 
 
 170.06 
 
 76.8 
 
 5.029 
 
 19.74 
 
 502 
 
 162.28 
 
 72.5 
 
 4.029 
 
 21.78 
 
 553 
 
 153.01 
 
 67.2 
 
 3.034 
 
 23.81 
 
 605 
 
 141.52 
 
 60.8 
 
 2.034 
 
 25.85 
 
 657 
 
 126.15 
 
 52.3 
 
 1.040 
 
 27.88 
 
 708 
 
 101.83 
 
 38.7 
 
 .980 
 
 28.00 
 
 712 
 
 100.00 
 
 37.8 
 
 .735 
 
 28.50 
 
 724 
 
 90.00 
 
 32.2 
 
 .544 
 
 28.89 
 
 734 
 
 80.00 
 
 26.7 
 
 .402 
 
 29.18 
 
 741 
 
 70.00 
 
 21.1 
 
 .294 
 
 29.40 
 
 747 
 
 60.00 
 
 15.6 
 
 .216 
 
 29.56 
 
 751 
 
 50.00 
 
 10.0 
 
 .162 
 
 29.67 
 
 754 
 
 40.00 
 
 4.4 
 
 .127 
 
 29.74 
 
 756 
 
 32.00 
 
 
 * By courtesy of the Buffalo Foundry and Machine Company. 
 
 Condensation. 
 
 The vapors from the pan are condensed by a spray 
 and column of water. It is desirable for the oper- 
 ator to know the temperature of the water just be- 
 fore and directly after going though the condenser, 
 as the efficiency of the condenser can be determined 
 by the temperature of the water. If the water com- 
 
Condensed and Evaporated Milk 51 
 
 ing from the condenser is cold, it shows that some- 
 thing is wrong. If the temperature of the condensing 
 water is 55° to 65° F. the water coming from the 
 condenser should be 15° to 20° colder than the tem- 
 perature of the pan, or about 110° F. ; below this 
 temperature there is sure to be much water wasted. 
 The amount of concentration or the ratio of the 
 condensed to the raw product, i. e., 1 to 3 or 1 to 
 3.5, etc., is determined by the market demand. The 
 amount of condensation in the pan is determined 
 by sampling and testing with a special hydrometer 
 calibrated in degrees Baume. Wheij the proper 
 concentration is reached, the milk should be drawn 
 off rapidly and cooled, unless superheated condensed 
 milk is being made. Superheated condensed milk is 
 made by turning live steam directly into the con- 
 densed milk as soon as the proper concentration is 
 reached. The temperature is raised to about 210° F. 
 This high heat precipitates the albumin and gives 
 the condensed milk a thick, heavy body, desired by 
 many ice-cream manufacturers. 
 
 Cooling the Milk. 
 
 Sweetened condensed milk should be cooled gradu- 
 ally. It is placed in large cans, which in turn are 
 placed in tanks. The cans are revolved and station- 
 ary paddles stir the milk. The water in the cooling 
 tank is at first fairly warm (about 90° F.) and the 
 milk is about 115° F. to 130° F. After a few 
 minutes cold water is supplied until the milk has 
 reached approximately 70° F. The time for this 
 cooling should be about two hours in all. 
 
 Another common practice is to place the con- 
 densed milk in large tanks and cool it by pumping 
 it through coils submerged in cold water or brine. 
 
52 A Handbook for Dairymen 
 
 Too rapid cooling must be guarded against in this 
 process, as this causes excessive sugar crystalliza- 
 tion. 
 
 The sweetened condensed milk, containing enough 
 sugar to preserve it, is usually put in small cans for 
 household use. The plain condensed milk, however, 
 spoils very rapidly unless refrigerated at a tempera- 
 ture of 32° to 40° F. It should not be allowed to 
 freeze. The refrigerator should be held at a uniform 
 temperature, otherwise spoilage is more rapid. Plain 
 condensed milk is used largely by ice-cream and 
 candy manufacturers and bakers. Because the de- 
 mand for plain condensed is not steady, it is often 
 necessary to hold it for a considerable period. 
 This can be done if the directions above are followed. 
 
 Evaporated Milk Processing and Sterilizing. 
 
 Evaporated milk is the term applied to sterilized, 
 plain condensed milk. It is made the same as plain 
 condensed but it is not concentrated quite so much; 
 usually the ratio is one to two or one to two and a 
 half. The milk is standardized in the holding tanks 
 and the finished product is standardized by the ad- 
 dition of distilled water. The condensed milk is 
 superheated, otherwise the later heating while ster- 
 ilizing would give a tough curd. After superheat- 
 ing, the milk is homogenized, which breaks up the 
 milk particles. It is then usually run into holding 
 - tanks until it can be packaged. 
 
 The package milk is sterilized to prevent it from 
 spoiling. The sealed cans are placed in the rack 
 of a large cast-iron sterilizer heated with steam. 
 The time and temperature may be varied to suit 
 conditions, but the milk should not be heated above 
 235° F. The cans are revolved in the sterilizer to 
 give uniform heating and to break up the curd. 
 
Condensed and Evaporated Milk 53 
 
 The sterilizer is equipped with steam and vacuum 
 gauges and automatic temperature controller and 
 temperature recorder. The cans are cooled either by 
 running cold water into the sterilizer or by immers- 
 ing the cans in cold water. They should be cooled in 
 15 to 20 minutes to a temperature of 70° to 80° F. 
 They are then placed in a shaker which shakes 
 out the curd which is formed because of the high 
 temperature. The cans are incubated for 20 to 30 
 days at a temperature of 75° to 85°. Defective cans 
 will swell and bulge. 
 
 Federal Requirements. 
 
 The federal standards for condensed and evapo- 
 rated milk are as follows : " Sweetened condensed 
 milk, sweetened evaporated, 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 the tolerances being allowed for, not less than 
 twenty-eight (28) per cent of total milk solids and 
 not less than eight (8) per cent of milk fat. 
 
 " Unsweetened condensed milk, evaporated milk, 
 concentrated milk, is the product resulting from the 
 evaporation of a considerable portion of the water 
 from the whole, fresh, clean lacteal secretion ob- 
 tained by the 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, all tolerances being allowed for, not 
 less than twenty-five and five-tenths (25.5) per 
 
54 A Handbook for Dairymen 
 
 cent of the total solids and not less than seven and 
 eight tenths (7.8) per cent of milk fat. 
 
 " 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 (28) per cent of 
 milk solids. 
 
 " Unsweetened condensed skimmed milk, evapo- 
 rated skimmed milk, concentrated skimmed milk, is 
 the product resulting from the evaporation of a con- 
 siderable portion of the water from skimmed milk, 
 and contains, all tolerances being allowed for, not 
 less than twenty (20) per cent of milk solids." 
 
 Continuous Evaporators. 
 
 Continuous evaporators evaporate the water from 
 the milk by heating the milk at atmospheric pressure. 
 No vacuum is used. With one type of machine the 
 milk is pre-heated and then delivered inside a hollow 
 copper drum. In this drum is a revolving dasher 
 with blades, similar to an ice-cream freezer. Out- 
 side the drum is an insulated jacket. Into the small 
 space between the drum and jacket live steam is ad- 
 mitted with 40 to 60 pounds' pressure. This heats 
 the milk and evaporates the water. Scrapers remove 
 the milk from the jacket and so keep it from burning. 
 Any desired concentration may be secured. After 
 being condensed the milk must be cooled. There is 
 a continuous flow of milk into the machine and of 
 condensed milk away from the machine. 
 
 Another type of condensing evaporator is some- 
 what similar, except that air is blown through the 
 
Condensed and Evaporated Milk 55 
 
 hot milk, assisting in the evaporation, and also re- 
 moving bad odors from the milk. 
 
 Condensed Buttermilk. 
 
 Condensed buttermilk is used largely for stock 
 and poultry foods. It should be sour and may be 
 condensed after any of the following methods : grav- 
 ity, centrifugal separation in vacuum pan or concen- 
 trator. 
 
CHAPTER VII 
 
 MILK POWDER 
 
 It is possible to reduce milk to a powder by the 
 elimination of the water and, at some later date, by 
 the addition of water again to turn the powder back 
 to milk. This powder is now commonly made in this 
 country after two different processes. One, the hot- 
 roll or film-drying process, and the other the spray 
 process. 
 
 The hot-roll or film-drying processes in common 
 use are the Hatmaker and Ekenberg. Others are 
 Parsburg, Gathsmaun, Just and Buflovak. 
 
 The spray processes are the Merrell-Soule and 
 Gray processes. Many of the processes and the 
 necessary apparatus are covered by patents, so that 
 manufacturers who use them are often obliged to 
 pay a royalty. 
 
 Description of Standard Processes. 
 
 The essential equipment required for the Hat- 
 maker process consists of two horizontal, hollow, 
 steam-heated, revolving metal cylinders. These 
 cylinders are installed sufficiently close to each other 
 so that all the milk comes in contact with the cylin- 
 ders. The surface of these cylinders is heated to 
 212° F. and below 270° F. The high temperature 
 reduces the solubility of the finished powder. The 
 patent claims that the treating of the milk with 
 calcium chloride or with the double salt of sodium 
 and calcium citrate, to reduce the acidity of the 
 milk, and with alkaline hypochlorite to preserve the 
 fatty acids in the finished product, causes the milk 
 
Milk Powder 57 
 
 powder to be more soluble. The milk is delivered 
 into the rolls from a distributing tank with an ad- 
 justable discharge. This tank is placed in the center 
 over and between the two rollers. The film of dried 
 milk is removed from the rolls by means of scrapers 
 and falls into receptacles. It has then to be placed 
 on porous racks in a dry kiln in order to dry it com- 
 pletely before it is ground. 
 
 The Ekenberg process is a film drier operating 
 in a partial vacuum. The machine which does the 
 drying is called an exsiccator. It consists of a re- 
 volving steam-heated drum inclosed in a vacuum 
 chamber. The temperature of drying varies with 
 the steam pressure in the drum. It is claimed that 
 the drying takes place at a temperature of 100° to 
 120° F. The fact that the milk is dried in a vacuum 
 makes it possible to do it at a low temperature. The 
 milk is first partially condensed by being brought in 
 contact with the concave ends of the rolls. It is 
 then sprayed on the rolls and dried milk is removed 
 by a scraper. Next it falls into a receptacle. This 
 receptacle may be removed when full by means of a 
 special arrangement without breaking the vacuum 
 about the roll. 
 
 The films of milk are placed on screen racks and 
 put in a dry kiln and held at a temperature of 90° F. 
 When completely dried the milk is ground and 
 packaged. It may be packed in various sized tin or 
 wood boxes or barrels. 
 
 The Merrell-Soule is a spray process of drying. 
 The milk is first partly condensed in an ordinary 
 vacuum pan. Then by means of a pressure pump 
 it is forced into the drying chamber in the form of a 
 fine spray or mist. Air is filtered and blown over 
 radiators in an air-heating chamber and then into 
 the drying chamber. This dry hot air meets the 
 
58 A Handbook for Dairyynen 
 
 spray of milk and takes up the moisture. The milk 
 falls on the floor of the drying chamber as milk 
 powder and the moisture-laden air escapes from the 
 drying chamber. 
 
 The Gray is also a spray process of drying. This 
 process is covered by several patents and several 
 different desiccating arrangements have been used. 
 
 Definition of Milk Powder. 
 
 The federal standards of milk powder are as fol- 
 lows : " Dried milk is the product resulting from the 
 removal of water from milk, and contains, all toler- 
 ances being allowed for, not less than twenty-six 
 per cent (26.0%) of milk fat and not more than five 
 per cent (5.0%) 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%) of moisture." 
 
 Much of the milk powder made in this country is 
 used in the warm states, where it is difficult to pro- 
 duce milk. Considerable quantities are exported to 
 tropical countries. Many ice-cream plants use it 
 to standardize the mix. Bakers also use it. 
 
CHAPTER VIII 
 
 CHEESE 
 
 Undoubtedly less is known about cheese making 
 than any other dairy manufacturing process. This 
 is probably due to the following facts : the many 
 varieties of cheese, the diversity of the process of 
 manufacture and the complex organic changes which 
 take place during cheese ripening. It is claimed by 
 some authorities that there are 700 known varieties 
 of cheese. The process of manufacture and curing 
 is different for each one. 
 
 There are certain varieties which are more ex- 
 tensively made than others. With these, it is known 
 that if certain operations are performed at a definite 
 time in a particular way that a definite result will 
 follow. But the reason is not known. Cheese may 
 be made from whole milk, skimmed milk or partially 
 skimmed milk. 
 
 The varieties of cheese commonly made from full 
 skimmed milk are cottage, hoop, pressed, bakers, pot 
 and kosher. Any of the other varieties may be made 
 from either whole milk or partially skimmed milk, 
 although most of them are made from whole milk. 
 
 Cheese may be classified in several ways : according 
 to the amount of moisture it contains, the country 
 in which it is made (each country is more or less 
 famous for some special variety of cheese), and the 
 combination of the texture and the method of 
 ripening. 
 
 Classification of these according to the amount 
 of moisture it contains : 
 
60 A Handbook for Dairymen 
 
 I. Soft cheese containing 45 to 75 per cent water. 
 They are Cottage Cheese, Pot Cheese, Hoop Cheese, 
 Neufchatel Cheese, Cream Cheese, Pimento Cheese 
 and Gervais Cheese. 
 
 II. Soft cheese, ripened, containing from 40 to 50 
 per cent water, include Camembert, Brie, d'Isigning, 
 Leiderkranz and Limberger. 
 
 III. Hard cheese, containing 30 to 45 per cent 
 water are Edam, Gouda, Cheddar, Brick, Gorgon- 
 zola, Swiss, Parmesan and Roquefort. 
 
 Classification of cheese according to countries in 
 which they originated, or in which they are commonly 
 and extensively made : 
 
 United States American Cheddar 
 
 p T 1 ( English Cheddar 
 
 "^ ^" I Stilton 
 
 France i Camembert 
 
 \ Roquefort 
 Switzerland ; Swiss 
 
 Holland / Edam 
 
 \ Gouda 
 
 Italy I Gorgonzol 
 
 a 
 Parmesan 
 
 Other countries make a characteristic cheese of 
 their own, but these forms are not commonly known 
 in this country. 
 
 Classification according to the method of ripening 
 and the texture: 
 
 ''Cheddar — Close texture 
 Swiss — Large shiny holes 
 Parmesan — Small holes 
 Hard Cheese J Gorgonzola — Ripened by mold, blue 
 All ripened | veined 
 
 Stilton — Ripened by mold, blue veined 
 Edam — Close texture 
 ^ Gouda — Close texture 
 
Cheese 
 
 61 
 
 Soft Cheese 
 
 'Cottage 
 
 1. Not ripened, eaten J Cream 
 
 fresh ) Neufchatel 
 
 ^and the like 
 
 2. Ripened by molds 
 
 (A) Outside the cheese, Camembert 
 
 (B) Inside the cheese, Roquefort 
 
 3. Ripened by bacteria alone 
 
 Limberger 
 Munster 
 
 What is usually termed cheese making may be 
 divided into two parts: one the making of the curd 
 or green cheese, and the other the ripening or de- 
 veloping of the cheese's characteristics, especially 
 the flavor, body and texture. 
 
 The making consists of coagulating the solids in 
 the milk, developing the desired amount of acid, and 
 the elimination of the water or whey. When first 
 made, the green curd or cheese is tough, rubbery and 
 tasteless. Due to the changes which take place dur- 
 ing the curing, the flavor develops and the body and 
 texture change. 
 
 In order to secure a cheese of the best quality, 
 the curd must be properly made and then cured. 
 The process of making any cheese consists of the fol- 
 lowing operations, which may be varied for each 
 variety of cheese. 
 
 For some varieties, such as Swiss and Limberger, 
 it is not necessary to ripen the milk, because the 
 cheese is made from sweet milk. INIilk is usually 
 ripened by the addition of starter. The temperature 
 at which the rennet is added and the temperature to 
 which the curd is heated varies with the different 
 cheeses, shown in the following table : 
 
62 
 
 A Handbook for Dairymen 
 
 Variety of Cheese 
 
 Temperature Rennet added 
 
 Temperature Curd is Cooked 
 
 Cheddar 
 
 84° 
 
 to 96° 
 
 F. 
 
 98° to 100° F. 
 
 Swiss 
 
 92° 
 
 to 96° 
 
 F. 
 
 128° to 135° F. 
 
 Limberger 
 
 90° 
 
 to 96° 
 
 F. 
 
 96° to 98° F. 
 
 Camembert 
 
 84° 
 
 to 86° 
 
 F. 
 
 Not cooked 
 
 Roquefort 
 
 82° 
 
 to 84° 
 
 F. 
 
 Not cooked 
 
 Edam 
 
 85° 
 
 to 88° 
 
 F. 
 
 93° to 96° F. 
 
 Neufchatel 
 
 72° 
 
 F. 
 
 
 Not cooked 
 
 Cream 
 
 72° 
 
 F. 
 
 
 Not cooked 
 
 Munster 
 
 84° 
 
 to 86° 
 
 F. 
 
 98° to 108° F. 
 
 Brick 
 
 92° 
 
 to 96° 
 
 F. 
 
 110° to 115° F. 
 
 The amount of rennet varies from 2 to 6 ounces 
 per thousand pounds of milk, depending upon the 
 varieties of cheese, the kind of curd desired, and the 
 temperature at which the rennet is added. The 
 length of time of coagulation depends upon the kind 
 of curd desired, and the succeeding operations. 
 Sometimes the curd is cut very soft, and sometimes 
 it is allowed to coagulate very slowly, taking several 
 hours or overnight. 
 
 The curd may be either cut or broken. It is 
 usually broken when the coagulated curd is put 
 directly into the draining forms, as in the making of 
 Camembert, Neufchatel and the like. The size of 
 the pieces into which the curd particles are cut de- 
 pends upon the rapidity of firming and the dryness 
 desired. The time to remove the whey varies with 
 each kind of cheese. Some varieties may be placed, 
 without heating or cutting, into the draining molds 
 and allowed to drain. A good example of this is 
 Camembert and Neufchatel. With the other varie- 
 ties it may be necessary to cut the curd, heat it and 
 allow time for the whey to be expelled or for the 
 curd to become firm. This may take one to three 
 hours from the time of coagulation before it is time 
 to remove the whey. 
 
 Some varieties of cheese, such as Cheddar, are 
 
Cheese 
 
 63 
 
 salted while the curd is yet in the vat and before it 
 is put to press. Other varieties are salted from the 
 outside after the cheese is entirely formed. This is 
 done by rubbing dry salt on the cheese or soaking 
 the cheese in a very salty brine. Many varieties of 
 cheese do not have to be pressed, for the curd will 
 naturally settle together, but with other varieties 
 the curd must be subjected to very heavy pressure 
 to make it go together. 
 
 Many cheeses which have been properly made are 
 ruined by improper methods of ripening. On the 
 other hand, no defects of manufacture can be 
 remedied during the ripening process. 
 
 Authorities disagree as to 
 what causes cheese ripening, 
 but it probably is due to 
 a combination of factors, 
 namely, humidity, tempera- 
 ture, micro-organisms, en- 
 zymes and chemical agents. 
 In the country where the 
 cheese originated, the ripen- 
 ing is a natural process and 
 does not need any special 
 attention. In a country 
 where the factors of humid- 
 ity and temperature are dif- 
 ferent, it is necessary to 
 try to duplicate the proper 
 climate conditions. To do 
 this, humidity and tempera- 
 ture recorders should be 
 installed in the curing rooms. 
 Thus, both humidity and tem- 
 perature can be accurately 
 judged and a record kept. 
 
 Foxboro Recording 
 Psychrometer for recording 
 the room temperature and 
 the wet bulb temperature, 
 thus giving a constant rec- 
 ord of humidity. Recorder 
 may be placed outside of 
 the area in which humidity 
 is controlled. 
 
64 A Handbook for Dairymen 
 
 While in the curing room cheese must have con- 
 stant attention. It must be turned and kept free 
 from mold. Some varieties, such ns Limbcrger, 
 Munster and Swiss, must be rubbed to develop a 
 rind. 
 
 If allowed fully to cure or ripen, the commercial 
 life of the cheese is very short. So it is the practice 
 to ripen the cheese partially when packaged and put 
 on the market. The time of packaging and market- 
 ing is so arranged that by the time the consumers 
 receive the cheese, it is fully ripe or cured and ready 
 for consumption. 
 
 Certain varieties of cheese, such as Cheddar and 
 Swiss, are made extensively during the summer when 
 milk is abundant. These cheeses are then put in 
 storage, after being partially cured. The cheese 
 should be held as near freezing and with as little 
 fluctuation in temperature as possible. There should 
 be a continuous record of the temperature changes. 
 The storage should be dry, so that the cheese will 
 not mold. Some varieties of cheese, especially Ched- 
 dar, when partially cured so that they have a firm, 
 dry, smooth rind, are dipped in hot paraffine. This 
 coat of paraffine prevents the evaporation of the 
 moisture, and tends to prevent the entrance of mold. 
 The paraffine is heated to 180° F. and the cheese 
 held in it four to six seconds. If the paraffine is too 
 cold or the cheese is damp the paraffine will not stick. 
 
CHAPTER IX 
 
 CASEIN AND MILK SUGAR 
 
 The making of commercial casein is a very simple 
 process, but one which requires strict observance of 
 temperature. Skimmed milk is heated to a tempera- 
 ture of 86^^ to 90 F., and the casein is precipitated 
 by the addition of sulphuric acid. Hydrochloric 
 acid and rennet are also used. The acid should be 
 diluted by pouring it into cold water. Never pour 
 the water into the acid. Just enough acid should be 
 used to get a clear whey, which shows that all the 
 casein has been precipitated. If too much acid is 
 used, it will cut the casein, causing it to be grainy 
 and chunky. As soon as it is coagulated, the curd 
 should be broken up and the whey drawn off. The 
 curd should then be thoroughly washed and worked 
 in water that is at least 180° F. The washing re- 
 moves the acid and the working causes the casein to 
 unite. After being worked, the curd will draw out 
 like taffy candy. If too much acid is used, it will 
 not draw out. 
 
 Casein may be precipitated as when making cot- 
 tage or pot cheese. It is then necessary to press 
 this curd to remove the whey, after which it is ground 
 and dried. It is claimed, however, that this method 
 does not give a good grade of casein. 
 
 In this condition, the casein is known as green 
 casein or green curd. It contains considerable mois- 
 ture and will spoil in a short time. It may be dried 
 in the same plant where made, or shipped to jobbers 
 who have drying plants. 
 
 The drying is usually done by grinding the green 
 curd and spreading it in thin layers on screen racks. 
 
66 A Handbook for Dairymen 
 
 These racks are placed in a dry kiln and the casein 
 dried for twenty-four hours. The heat for drying 
 is obtained by blowing air over hot radiators. The 
 temperature of the kiln should not be above 115° F. 
 The fan and ventilators are usually connected with 
 a thermostat control and the kiln with a recording 
 thermometer. If the temperature rises too high, it 
 discolors the casein and reduces its solubility. 
 Rotary dryers and vacuum dryers are also used con- 
 siderably for drying casein. 
 
 Casein is used in the making of certain glues, 
 paints, papers, textiles and prepared foods. It is 
 also used for imitation ivory, horn, etc. 
 
 Milk Sugar. 
 
 Milk sugar is manufactured as follows : Whey, 
 obtained from commercial casein plants or cheese 
 factories, is acidified and heated to its boiling point 
 in large vats, in order to precipitate the albumin. 
 The solution is then treated with calcium hydroxide 
 and evaporated in a vacuum pan until it forms a 
 syrup. It is then filtered and evaporated again at 
 about 100° F. to a thick syrup, which is removed, 
 placed in shallow containers and cooled. After one 
 or two days it has crystallized into the crude yellow 
 sugar. It is then placed in a centrifugal machine 
 provided with sieves and washed to remove impuri- 
 ties. The washed crystals are redissolved in hot 
 water and treated with chemicals. The clear liquid 
 is then heated to about 170° F. and filtered through 
 charcoal to remove coloring matter. It is now con- 
 densed to a solid mass in a vacuum pan, which is 
 washed and dried on racks in a drying room in which 
 a temperature of approximately 140° F. is main- 
 tained. When dry it is powdered and packed for 
 shipment. 
 
CHAPTER X 
 
 THE POWER PLANT 
 
 It is not the province of this book to discuss the 
 question whether a steam boiler, a gas engine, or an 
 electric motor is the best equipment for the dairy 
 power plant. There are operating conditions under 
 which a combination of all three of these would prove 
 to be the most economical in the end ; and there are 
 other conditions which seem to leave little choice to 
 the dairyman. The relative local cost of coal, gaso- 
 line, and electricity would have to be considered very 
 carefully, and the particular milk products to be 
 manufactured, and a dozen other purely individual 
 conditions. We content ourselves, therefore, with 
 referring the dairyman interested in this important 
 question to Bulletin 747 United States Department 
 of Agriculture : " The Economical Use of Fuel in 
 Milk Plants and Creameries," by John T. Bowen. 
 In this bulletin of forty-seven pages every phase of 
 the dairy power-plant problem is discussed in a 
 manner that makes it extremely valuable to the 
 Dairy Industry. 
 
 Whatever be the kind of power employed, however, 
 the power plant must certainly not be overlooked 
 when the question of indicating and recording instru- 
 ments is being considered. Everything gained in the 
 way of productive efficiency and economy in the milk- 
 handling rooms may easily be lost by neglect in the 
 power plant. The cost of fuel alone may run higher 
 than that of any other item of operating expense; 
 and the waste of steam and water, of brine and 
 ammonia, may more than offset the economical ad- 
 
68 A Handbook for Dairymen 
 
 ministration of other departments. It cannot, there- 
 fore, be overemphasized that efficiency and economy 
 in the power plant are fully as important as the con- 
 trol of temperature and pressure in the milk-han- 
 dling rooms, and that they are just as easily attained. 
 
 All this applies not only to large modern plants 
 of complex character, but also to the small plant 
 with its inadequate and, sometimes, antiquated equip- 
 ment. Indeed, such small plants often offer even 
 greater opportunities for improvement and economy 
 through the installation of the proper instruments. 
 Whether the boilers and refrigerating macliines are 
 old or new, large or small, the operators should be 
 provided with high-grade indicating and recording 
 instruments, in order that they may have at all times 
 sufficient information about conditions to maintain 
 a high efficiency and to prevent the loss of costly 
 heat units. 
 
 It is assumed here that steam power and some 
 system of artificial refrigeration are used. 
 
 Now the choice of indicating and recording in- 
 struments for the power plant should be determined 
 by a careful consideration of kind, quantity, and 
 quality. To overload a small plant with instruments 
 that cannot be used to advantage is to gain nothing 
 but expense; yet it is just as shortsighted to attempt 
 to do without those that are really essential to estab- 
 lish a high plant standard. In order to make the 
 installation of instruments an investment rather 
 than an expense, study the performance of the 
 plant itself, note the variable conditions which affect 
 efficiency, and then determine what instruments are 
 needed. 
 
 The particular instruments mentioned here are 
 simply suggestive. It may be that some plants will 
 not need them all, but it is very probable that even 
 
The Power Plant 69 
 
 the engineer of the smallest plant will discover a few 
 suggestions that will help him to reach a higher 
 eflSciency and a lower cost in his department. 
 
 For the boiler room we recommend Recording 
 Pressure Gauges for steam, Recording and Indicat- 
 ing Thermometers for feed-water, stack, steam, and 
 economizer temperatures ; Recording and Indicating 
 Draft Gauges, and a CO Recorder for flue-gas 
 analysis. 
 
 In the refrigerating room, thermometers should be 
 provided for the ammonia compressors, freezing 
 tanks, condenser-water, forecooler-water, liquid am- 
 monia, brine lines and brine tanks. A Two-Pen 
 Recording Pressure Gauge for both low and liigh 
 pressure ammonia attached to the compressor will 
 give a positive check on the efficiency of its operation. 
 
 A knowledge of the temperatures of the brine 
 entering and leaving the cooler is of utmost im- 
 portance to a dairyman. Unless he has accurate 
 and continuous information of these temperatures 
 the efficiency of the plant cannot be maintained. Re- 
 cording thermometers tell the whole story, and from 
 a study of the charts the temperature of brine flow 
 and refrigerant can be regulated. 
 
 For the condenser-water, recording thermometers 
 make it possible for the operator to estimate the 
 number of gallons required per ton of refrigeration 
 by recording the temperature of the water as it runs 
 on the condenser and as it leaves. They give also a 
 check on operating conditions. If the records show 
 an increase of temperature above normal of the 
 water leaving the condenser, the water pump, or 
 system needs attention. If the temperature of the 
 water running over the condenser shows a decrease, 
 less ammonia has been delivered to the condenser. 
 
 On the ammonia compressor, recording thermome- 
 
70 A Handbook for Dairymen 
 
 ters will tell you whether there is enough ammonia 
 in the line, whether it returns superheated, whether 
 the cooling of the compressor — either by water 
 jacket or liquid injection — is correct. By record- 
 ing both the suction and discharge temperatures of 
 the compressor, the operator has an accurate and 
 continuous picture of what is going on while the 
 plant is in operation. 
 
 These are only a few isolated instances of what 
 can be done in the refrigerating room alone by an 
 intelligent use of recorders. Wherever possible in 
 the boiler room and the refrigerating room, record- 
 ing instruments should be installed. Their slightly 
 additional cost above indicating instruments is far 
 offset by the greater value gained by the continuous' 
 records which the operator can compare and study. 
 If properly installed and faithfully used, these in- 
 struments will provide the engineer with the most 
 valuable information on all the conditions upon 
 which the productive efficiency and economy of the 
 plant depend. 
 
 It is worth emphasizing that, where it is a ques- 
 tion of temperature, or pressure, guessing is un- 
 scientific, uneconomical, and unsafe. In the power 
 plant, knowledge alone is power ; not memory — that 
 is too treacherous ; not scraps gathered at irregular 
 intervals by glancing at an indicator — that is the 
 little knowledge which is a dangerous thing. What 
 is needed is complete recorded knowledge of what is 
 happening all the time in and around the boiler and 
 the refrigerating equipment. And this is just what 
 recording instruments give. They are not only per- 
 petual guides to the operators, but they give the 
 engineer an opportunity to compare various records 
 and thus establish an efficient operating standard. 
 
 Finally, cheap indicating and recording instru- 
 
The Power Plant 71 
 
 ments are, like most other cheap things, dear at any 
 price. In the milk-handling rooms and in the power 
 plant accurate knowledge of temperatures and pres- 
 sures often creates just that distinction between the 
 dairy product that has to be sold at a loss because 
 something is not quite standard about it, and the 
 product that is perfect in purity and flavor because 
 the conditions essential to quality have been care- 
 fully watched and controlled. Real quality instru- 
 ments — high-grade, accurate, and dependable — 
 very soon save many times their initial cost, and 
 should never be considered as an extra expense but 
 as a definite investment. Nowhere is the " Penny- 
 Wise, Pound-Foolish " policy more to be avoided 
 than when equipping the dairy with indicating and 
 recording instruments. Get the best. 
 
72 
 
 Dairy Instruments 
 
 Some Foxboro Dairy Instruments 
 
Dairy Instruments 73 
 
 I'OXJ^RO DAIRY INSTRUMENTS 
 
 Foxboro Dairy Instruments are furnished in the 
 standard white-enameled, round-form, dust-proof, mois- 
 ture-proof case, as illustrated. Full nickel plate or 
 other finishes can be supplied to match existing equip- 
 ment. Sanitary fittings are supplied to suit any stand- 
 ard make of pasteurizer. 
 
 Figure 1 — ■ Foxboro Automatic Temperature Re- 
 corder-Controller for the dairy. Combines temperature 
 controller and recording thermometer. Particularly valu- 
 able for regulating and recording temperature in pas- 
 teurizers, storage rooms, hardening rooms, drying kilns, 
 drying rooms, curing rooms, or wherever it is desired 
 to keep a careful check on holding temperatures and 
 maintain permanent records of these temperatures. 
 
 Figure 2 — Foxboro Automatic Temperature Con- 
 troller for dairy use wherever it is desired to main- 
 tain a definite temperature without keeping a record of 
 the temperature. 
 
 Figure 3 — Foxboro Long-Distance Dial-Type Dairy 
 Indicating Thermometer used extensively on pre-heaters, 
 cookers, tanks, washers and other equipment if no record 
 is desired. It replaces the ordinary glass thermome- 
 ter, eliminating breakage and mercury contamination. 
 The instrument shown is provided with double electric 
 alarm attachment for giving a warning signal when 
 the temperature rises to a certain point or falls below 
 a certain point. This device is also provided on re- 
 cording instruments. 
 
 Figure 4 — Foxboro Long-Distance Recording Dairy 
 Thermometer. For every required temperature range 
 in the Dairy Industry. Used in bacteriological labora- 
 tories, on pasteurizers, receiving vats, pre-heaters, 
 coolers, holding tanks, storage rooms, ripeners, ageing 
 tanks, freezers, brine tanks, hardening rooms, sterilizers, 
 condensers, drying kilns, drying rooms, cheese vats, 
 curing rooms and in the refrigerating plant. 
 
 Figure 5 — Foxboro Recording Pressure and Vac- 
 uum Gauge used on homogenizers, viscolizers, sterilizers, 
 evaporators, vacuum pans, condensers, drying cylinders 
 and steam lines. 
 
74 Controller and Thermometer Bulbs 
 
 Some Foxboro Controller and Thermometer 
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76 
 
 Power Plant Instruments 
 
 Some Foxboro Power Plant Instruments 
 
Power Plant Instruments 77 
 
 JlOXBORO 
 
 POWER PLANT INSTRUMENTS 
 
 P'igures 1 & 2 — Foxboro Recording and Indicat- 
 ing Thermometers for power plants. Used on feed- 
 water heaters, stacks, economizers, steam lines, ammonia 
 compressors, freezing tanks, condensers, forecoole'rs, 
 brine lines, brine tanks. 
 
 Figures 3 & 4 — Foxboro Recording and Indicat- 
 ing Pressure Gauges for power plants. For use on 
 boilers, steam lines, liquid lines and compressors. 
 
 Figure 5 — Foxboro Two-Pen Recording Pres- 
 sure Gauges for recording compressor suction and dis- 
 charge pressures. Low pressure two-pen" recorders are 
 used for recording draft at any two parts of the boiler 
 system. 
 
 For dairies whose power requirements necessitate 
 plants of large capacity Foxboro-Heath COg Recorders 
 produce permanent records of the COo content in the 
 flue gases. Their use greatly increases the efficiency and 
 economy of plant operation. For large plants we 
 also recommend the use of Foxboro Triplex Draft 
 Gauges for indicating pit pressure, draft in the last 
 pass and in the furnace above the fire. Although this in- 
 strument was only recently placed on the market its 
 accuracy, compactness and easy reading quality have 
 made it exceedingly popular with engineer and fireman. 
 
 Write us for further information concerning these 
 instruments. 
 
Legal Standards for Dairy Products 
 
 
 
 2 
 
 
 
 Condensed Milk 
 
 r^"'' 1 Ci 
 Cream 
 
 
 
 Milk 
 
 a 
 
 «3 
 
 Cream 
 
 Butter 
 
 
 
 lEESE 
 
 
 
 States 
 
 
 
 
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 DNSWEET- 
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 % Total 
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 Alabama t . . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Arizona . . . 
 
 
 8.5 
 
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 18 
 
 80. 16 
 
 7.7 28. 
 
 7.7 
 
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 California . . . 
 
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 9.3 
 
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 83. 12 
 
 
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 11.76 8.5 3.25 
 
 9.25 
 
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 82.5. . 
 
 
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 8 
 
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 11.2 8. 3.2 
 
 9.3 
 
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 82.5. . 
 
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 14. 
 
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 . . . 8.5 3. 
 
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 82.5 . . 
 
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 18 
 
 82.5 
 
 
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 12 
 
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 18 
 
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 50 
 
 
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 50 
 
 
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 3.25 
 
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 16 
 
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 7.8 26.5 
 
 14. 
 
 12 
 
 60 
 
 
 U. S. Dept. of 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Agriculture 
 
 1 
 
 
 18 
 
 82.5 
 
 12 
 
 8. 28. 
 
 7.8 1 2.'5.5 
 
 14. 
 
 12 
 
 50 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 * U. S. Department of Agriculture Standards, 
 t No State Standards. 
 
 Note: — U. S. Department of Agriculture Standards for milk: Milk is 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 five days after calving, or 
 such longer period as may be necessary to render the milk practically colostrum free. 
 
 Pasteurized Milk is milk that has been subjected to a temperature not lower than 145 de- 
 grees Fahrenheit for not less than thirty minutes. Unless it is bottled hot, it is promptly 
 cooled to 60 degrees Fahrenheit or lower. 
 
INDEX 
 
 Ageing the Mix 43 
 
 Alarm Attachment for Thermometers. . 72, 73 
 Automatic Temperature Controller. . . . 72, 73 
 Automatic Temperature Recorder-Con- 
 troller 72, 73 
 
 Bacteria, Effect of Temperature on 2 
 
 Bacteriology 9 
 
 Board of Health Regulations 26, 29 
 
 Boiler Room Instruments 69, 76, 77 
 
 Boiling Points of Water at Different 
 
 Vacua 50 
 
 Bottle Method of Pasteurization 28 
 
 Brine, Properties of 43 
 
 Bulbs, Controller and Thermometer. . . 74, 75 
 
 Bulgaricus Starter 16 
 
 Butter Making 19 
 
 Butter Storage 24 
 
 Buttermilk, Commercial Preparation of. . 17 
 
 CO2 Recorder 69, 77 
 
 Casein 65 
 
 Cheese 59 
 
 Cheese, Culture for 16 
 
 Cheese, Classification According to Coun- 
 try of Origin 60 
 
 Cheese, Classification According to Method 
 
 of Ripening. 60 
 
 Cheese, Classification According to Mois- 
 ture Content 60 
 
 Cheese Ripening, Influence of Humidity 
 
 on _. 5 
 
 Cherry Pasteurizer, Thermometer Bulbs 
 
 for. 74, 75 
 
 Chloride of Calcium, Properties of 43 
 
 Churning 22 
 
 Clarifier, Operation of 27 
 
 Cleanliness in Starter Preparation 12 
 
 Coagulation of Starter 16 
 
 Condensation 50 
 
 Condensation, Amount of 51 
 
 Condensed and Evaporated Milk 48 
 
 Condensed Buttermilk . 55 
 
 Continuous Evaporators 54 
 
 Controller Bulbs 74, 75 
 
 Controllers, Automatic Temperature. . . 72, 73 
 
 Cooling after Pasteurization 30 
 
 Cooling Condensed Milk 51 
 
 Cream 26 
 
 Cream, Separation for Butter Making. . . 19 
 
 Cream Separator, Efficiency of 19 
 
 Cream Standardization 31 
 
 Culture, Adding the 13 
 
 Curd, Preparation of 61 
 
 Dairy Instruments 72, 73 
 
 Davis Pasteurizer, Thermometer Bulbs 
 
 for. . . 74,75 
 
 Deterioration in Storage 4 
 
 Dial-Type Thermometers, Dairy 72, 73 
 
 Draft Gauges 76, 77 
 
 Drying Casein 66 
 
 Drying of Cheese 62 
 
 Drying of Milk Sugar 66 
 
 Economy Pasteurizer, Thermometer Bulbs 
 
 for 74. 76 
 
 Page 
 
 Ekenberg Process 57 
 
 Electric Alarm Attachment for Thermom- 
 eters 72, 73 
 
 Elyria Pasteurizer, Thermometer Bulbs 
 
 for 74, 75 
 
 Emulsifiers 41 
 
 Evaporated Milk 48 
 
 Evaporated Milk Processing and Steri- 
 lizing 52 
 
 Federal Requirements for Condensed and 
 
 P>aporated Milk 53 
 
 Federal Standards tor Dairy Products ... 78 
 
 Flash Method of Pasteurization 28 
 
 Flavor, Influence of Temperature on 3 
 
 Freezing of Ice Cream 45 
 
 Gauges, Dairy Recording 72, 73 
 
 Gauges, Pressure, Recording and Indi- 
 cating for Power Plants 69, 76, 77 
 
 Gauges, Two-Pen Pressure, Record- 
 ing 69, 76, 77 
 
 Gray Process 58 
 
 Hardening of Ice Cream 46 
 
 Hatmaker Process 56 
 
 Holding of Milk after Pasteurization 30 
 
 Holding Method of Pasteurization 28 
 
 Homogenizers 41 
 
 Humidity in Cheese Curing Rooms 63 
 
 Humidity, Influence of, on Dairy Oper- 
 ations 5 
 
 Ice Cream 39 
 
 Ice Cream Recipes 40 
 
 Incubating Process, Temperature Rec- 
 ords of 9 
 
 Incubation, Effect of Temperature on. ... 10 
 Indicating Instruments, Power Plant 68, 76, 77 
 
 Indicating Thermometers, Dairy 72, 73 
 
 Instruments, Power Plant 68, 76, 77 
 
 Keeping Quality of Milk, Effect of Tem- 
 perature on 2 
 
 Lactic Acid Starter 10 
 
 Legal Standards of Dairy Products 78 
 
 Long-Distance Thermometers, Dairy 72, 73 
 
 Merrell-Soule Process 57 
 
 Micro-Organisms, Effect of Temperature 
 
 on 1 
 
 Micro-Organisms, Growth of, in Dairy 
 
 Products 2 
 
 Milk 26 
 
 Milk Powder 56 
 
 Milk Powder, Definition of 58 
 
 Milk Sugar 66 
 
 Milk Standardization SO 
 
 Mixing 41 
 
 Mixing Machinery for Ice Cream Plants 41 
 
 Moisture Content of Cheeses 60 
 
 "Mother" Starter 13, 15 
 
INDEX — Continued 
 
 Page 
 Open Vats, Thermometer Bulbs for. ... 74, 75 
 Over-run 
 
 Paraffining of Cheese 64 
 
 Pasteurization *° 
 
 Pasteurization for Ice Cream Plants 40 
 
 Pasteurization of Cream for Butter Makmg 20 
 
 Pasteurization of Starter Milk . H 
 
 Pfaudler Pasteurizer, Thermometer Bulb 
 
 for 74,75 
 
 Power Plant, Dairy ■ ■ • ■ 67 
 
 Power Plant Instruments 68, 7b, 77 
 
 Pre-Heating of Milk ■ ■ 26 
 
 Pressure (lauges, Recording, for Boiler 
 
 Rooms 69,76,77 
 
 Pressure, Influence of, on Dairy Oper- 
 ations ^ 
 
 Pressure, Vacuum Pan _■ *'' 
 
 Pressure, Viscolizing or Homogenizing ... H 
 
 Propagation, The Second Day's 14 
 
 Psychrometer, Recording 63 
 
 Quality Instruments, Value of 70 
 
 Quality of Products, Effect of Temper- 
 ature oil 3 
 
 Ranges, Pasteurizer Thermometer 75 
 
 Recipes for Ice Cream 40 
 
 Recorder, CO2 69,77 
 
 Recording Gauges, Dairy '^^' Z, 
 
 Recording Instruments, Power Plant 68, 76, 77 
 Recording Instruments, Value of, in Power 
 
 Plants 70 
 
 Recording Thermometers, Dairy 72, 73 
 
 Rectangle Method of Standardizing 31 
 
 Refrigeration of Condensed Milk 52 
 
 Refrigeration, Importance of, in Ice Cream 
 
 Making 39 
 
 Refrigerating Room Instruments. . . 69, 76, 77 
 Rennet, Addition 01, in Cheese Making 62 
 
 Ripening, Cheese 63 
 
 Ripening Methods, Cheese 60 
 
 Ripening of Cream 20 
 
 Salt Solutions, Properties of 43 
 
 Salting of Butter 23 
 
 Salting of Cheese 62 
 
 Simplex Pasteurizer, Thermometer Bulbs 
 
 for 74.75 
 
 Souring of Ice Cream Mix 44 
 
 Specific Gravity of Milk and Cream 37 
 
 Standardizing Milk and Cream 31 
 
 Standards for Dairy Products, U. S. Dept. 
 
 of Agriculture 78 
 
 Starter , 10, 15, 21 
 
 Starter Milk, Selection of 11 
 
 Page 
 
 Startoline 1^ 
 
 State Standards for Dairy Products 78 
 
 Sterilizing of Evaporated Milk 52 
 
 Storage, Influence of Temperature on. . . . 4 
 
 Storage of Butter 24 
 
 Storage of Cheese 64 
 
 Superheated Condensed Milk 61 
 
 Swell, How to Obtain 46 
 
 Temperature, Casein Dry-Kiln 66 
 
 Temperature, Cheese Curing Room 63 
 
 Temperature, Churning •,. ' ' ' *^ 
 
 Temperature, Condensed Milk CooUng. . 51 
 
 Temperature, Condensing Water 51 
 
 Temperature, Cooling ^0 
 
 Temperature Curd is Cooked in Cheese 
 
 Making 63 
 
 Temperature, Ekenberg Process 67 
 
 Temperature, Emulsifying •,.••;• *1 
 
 Temperature, Hatmaker Process Cyhnders 56 
 
 Temperature, Ice Cream Freezing 45 
 
 Temperature, Ice Cream Hardening Room 47 
 
 Temperature, Ice Cream Mix 44 
 
 Temperature, Influence of, on Dairy Oper- 
 ations 1' 3> 4 
 
 Temperature, Milk Holding 30 
 
 Temperature, Milk Sugar Drying Room 66 
 
 Temperature, Pasteurizing 28 
 
 Temperature, Pre-Heating 26 
 
 Temperature, Refrigeration, of Condensed 
 
 Milk ••■••■ S2 
 
 Temperature, Rennet is Added in Cheese 
 
 Making • • 62 
 
 Temperature, Sterilizing of Evaporated 
 
 Milk 62 
 
 Temperature, Vacuum Pan 49 
 
 Texture, Influence of Temperature on 3 
 
 Thermometer Bulbs '^*'V 
 
 Thermometers, Dairy Recording ■ ■ . • ■. 72, 78 
 Thermometers, Recording and Indicating, 
 
 for Boiler Rooms 69, 76, 77 
 
 Thermometers, Recording and Indicating, 
 
 for Refrigerating Rooms 69, 76, 77 
 
 Triplex Draft Gauges 76, 77 
 
 U. S. Department of Agriculture Stand- 
 ards for Dairy Products 78 
 
 Vacuum Gauges, Dairy Recording 72, 73 
 
 Vacuum Pan Temperatures 49 
 
 Viscolizers 41 
 
 Washing of Butter 22 
 
 Weight of Milk and Cream 37 
 
 Whey Butter ■ ■• • • 24 
 
 Wizard Pasteurizer, Thermometer Bulbs 
 tor 74,76