In the first chapter the composition of cow’s milk and the nature of its constituents have been considered, the most important tests for its richness and purity have been described, and the ferments have been mentioned which instigate changes for good or for bad, together with the means at disposal for regulating their activity. To use these means intelligently in handling milk and its products is the key to the dairyman’s success.

We shall now briefly consider the various steps that are of importance in modern dairy industry.

MILK SUPPLY

In the first place, the farmer must furnish pure, clean, unadulterated milk, fresh from the cow and cooled immediately after milking. His cows must be healthy.

Bovine Tuberculosis.—Many milk-cows, for the very reason that they have been bred with the one purpose in view of turning all their food into milk and wasting as little as possible in building up the body, are more or less weak-chested and apt to suffer from tuberculosis. Unless this disease is so far advanced as to affect the general health of the cow, or it has spread to the milk organs, the udder and the teats, it is not so dangerous as has heretofore been supposed. It is now held by the great majority of physicians that bovine tuberculosis is hardly ever transmitted to grown persons and seldom to children. Neither is it hereditary. Nevertheless, wherever it is possible to have the herd tested with tuberculin, segregating, if not killing, the animals which show by reaction that they are somewhat tuberculous, it should be done. Milk from such cows should always be pasteurized.

Milk as a Disease Carrier.—A greater danger lies in the fact that, warm as it comes from the cow, milk is an ideal medium for human disease germs to grow in, and may thus become a great conveyor of such germs. For this reason it is of the greatest importance that the milkers are healthy and clean, that the udders and teats be free from dirt, and the milk pail covered as far as possible; the barn must be clean, and every source of infection excluded. This fact also points to the advisability of pasteurization. On page 23 a chart is shown, published by the Toronto Board of Health and indicating the temperatures at which various germs of disease are made harmless.

Bacterial Count.—The test for clean milk now mostly used is the “Bacterial Count,” the number of bacteria—or rather colonies of bacteria—found in a cubic centimeter of the milk. It would be better if the nature or quality of the bacteria could be taken into consideration as well as the quantity, but that being as yet impracticable, the next best thing is to depend upon the number. Ordinary good milk often contains hundreds of thousands of bacteria in a cubic centimeter, but where the greatest cleanliness is observed the number may be less than 1,000.

Certified Milk is now sold in many cities which, according to varying city ordinances, is guaranteed to have less than 10,000 or 20,000 or 30,000 bacteria, as the case may be.

The cost of producing certified milk places it beyond the reach of the great majority of consumers. But such care and cleanliness as can be observed by the farmer and the milkman without extra expense should be insisted upon, and milk which nevertheless contains a large number of bacteria can be made safe by pasteurization.

The Sanitary Code.—The regulation of the production and delivery of milk in cities and towns as well as at creameries and cheese factories, the “Sanitary Code” established by state and municipal health authorities, has been very effective in improving the quality of the supply. So enormous have been the improvements in caring for and handling the products by the large establishments engaged in the delivery of milk as to make the increase in cost seem trifling compared with the great benefit to the public health secured by these agencies.

New York State Milk Grading.—The New York State Board of Health prescribes a grading for milk offered for sale, the most important features of which are as follows:

Certified.—Must be produced under specially sanitary conditions approved by a county medical commission.

Grade A Raw.—Cows must be tuberculin tested and milk must not contain over 60,000 bacteria per cubic centimeter.

Grade A Pasteurized.—Cows must be subjected to physical examination and milk must not contain more than 200,000 bacteria before, nor more than 30,000 after pasteurization.

Other grades permitted under the rules, all subject to inspection and approval of the authorities, are:

Deliveries must be made within a certain time after production or pasteurization, barns and milk stations are inspected, and altogether such safeguards are employed as to make the supply exceedingly safe and reliable.

City Delivery.—In villages and small cities the milk supply is still to a large extent in the hands of farmers who come to town early in the morning peddling their milk, often at considerable waste of time for horse and man. Or a number of peddlers go over the same route so that it takes a dozen wagons to cover a town where three or four could do it.

As long as there was no efficient regulation as to price and quality such waste was perhaps unavoidable, as competition on the part of the producers and distributors was the only means of protection for the consumers. But lately state and municipal control is being exercised to such an extent as to largely eliminate the danger of poor milk and exorbitant prices. Further development of organized delivery systems so much to be desired for sanitary as well as for economical reasons, may be looked for as soon as normal conditions return after the close of the war. The delivery of milk is one of the things that in the interest of public health must be under the strictest official control, and co-operation between farmers and consumers is the logical system for elimination of unnecessary expenses of distribution and for prompt and satisfactory service. Their interests are or should be identical and both classes are hurt by inefficient and wasteful delivery.

In the large cities there has grown up an industry which largely monopolizes the milk supply and which until lately was powerful enough to dictate prices and conditions both for producers and consumers. Several attempts have been made from time to time by farmers to combine to regulate prices and dictate the terms to the middlemen. Such attempts have, however, invariably failed as long as they were built on false economic principles and prompted by selfish interests only. No farmers’ association can be strong enough to ignore the law of supply and demand, and it is only quite recently that the Dairymen’s League has succeeded in influencing the market by taking into consideration the actual cost of production of milk as worked out by the agricultural colleges, and fixing the price on a scientific basis. There is one other element entering into the causes on which the price to the consumers depends, namely, Transportation, and while municipal boards of health are looking after the sanitary conditions and prevention of adulteration, State and Federal authorities are stepping in as moderators or arbitrators to reconcile the interests of the Producers, the Railroad Companies, the Distributors and the Consumers. The next step in the development will no doubt be towards full co-operation between producers and consumers and, to a large extent, elimination of the “middlemen.”

It should not be forgotten, however, that while the much abused middlemen in time past have been able to dictate terms and prices and have often abused the privilege; they have at the same time used their influence and power to improve the milk supply. As the supply of oil and gasoline has been perfected and cheapened by the all-powerful Standard Oil Co. as a monopoly crushing all competition, so the “Milk Trust” has improved the distribution of milk and has built up the magnificent sanitary plants in which milk is handled, pasteurized, bottled and distributed in a way that might not have been possible without the monopoly. It has served a good purpose, but has at the same time acquired such power that official control has become necessary for the protection of producers and consumers alike, and the time may be near when these two classes will combine and take the matter into their own hands so that the distribution may be done at actual cost.

Milk Stations are plants erected in dairy sections in the country either by the city milk supply houses or by co-operating farmers, where the milk is delivered and handled so as to make it ready for shipment to the city. As in the creamery and the cheese factory, the milk is carefully examined and, if it is not sweet and pure, it is rejected and sent back to the farm. Any impure flavor remains in the cover for some time and is easily detected by smelling of the cover as soon as it is removed from the can.

A sample is taken and put aside for the Babcock test and perhaps another for the Fermentation test. Each farmer’s milk is weighed in the Weigh Can and run through a cheese-cloth strainer. The further treatment varies in different plants. The milk may simply be cooled by running it over a cold water or brine cooler and placing it in shipping cans in the refrigerator or in ice water until the milk-train comes along to pick up the cans. Or it may be clarified by running it through a centrifugal machine, the same as a separator, in which, however, cream and milk are not separated, but impurities are thrown out by the centrifugal force and deposited on the wall of the bowl, and the purified milk may then be pasteurized and bottled before being shipped to the city.

Arriving in the city in iced cars the milk is taken to one of the elaborate plants in which it is pasteurized and bottled, if that has not been done at the country station. The machinery used in these plants is getting more and more perfect and expensive and leaves little to be desired as to sanitary requirements and economy in handling. Pasteurizers, bottling machines, bottle-washing machines, conveyors, etc., are wonders of ingenuity, and one needs only to see one of these modern plants to understand that in a large city milk can only be handled to advantage in expensive establishments.

Skim Milk is one of the cheapest of foods and under proper regulations its sale should not be prohibited. The reason why in times past skim milk has been discredited and excluded from sale was that, as produced by the old methods of raising the cream, before the advent of the separator, it was always more or less old and sour before it was available and certainly before it could be distributed to consumers. Under such conditions it was hardly ever fit for human food. But when produced by the separator and pasteurized and cooled immediately after—within a few hours after milking, which is entirely feasible—it is an excellent and nutritious food for adults and even for children over two years of age. Ripened with a pure culture of lactic acid bacteria, it makes a healthful, refreshing drink, like buttermilk. Only when it is allowed to sour without proper care or control does skim milk, as whole milk does, become unfit for food or drink. On a cold winter morning when men are going to work (or perhaps are looking for work which they cannot find), and children are on their way to school, often underfed, a street-corner wagon or stand where boiling hot, fresh, sweet skim milk might be distributed at a cent or two a glass would be a blessing in any city.

CREAM

When new milk is left at rest the cream will rise to the top and after 12 to 24 hours a cream-line can be seen in the bottle. This cream-line is sharper and more easily seen in raw milk than in pasteurized milk and its absence is not always a sure sign of lack of richness or purity of the milk. By cooling the milk thoroughly so that it will keep, almost all the cream will be at the top in forty-eight hours and can be skimmed off. The cream can be used for coffee or on cereals or fruits or puddings; the skim milk left will still hold ½% or more of butter-fat and can be used to drink or for cooking.

The Separator.—On the farm or in the creamery the cream is no longer raised by gravity, that is, by letting the milk “set” either in shallow pans on the kitchen shelf or in deep cans in ice water, but the fresh, warm milk is run through the separator in a continuous stream.

It was noticed that the rising of the cream due to the difference in specific gravity between the butter-fat and the milk-“serum” (the watery solution of the other constituents) might be greatly hastened by subjecting the milk to centrifugal force. This physical phenomenon was taken advantage of in the first conception of the separator where it was shown that if a pail of milk was whirled around like a stone in a sling the heavier milk-serum would be thrown towards the bottom of the separator pail with so much greater force than the lighter cream (butter-fat mixed with a small part of the serum) that the separation which would take 48 hours in the milk at rest, could be accomplished in a few minutes when exposed to centrifugal force. From this early crude attempt the continuous bowl-separator was developed and still later a number of divisions in the bowl were designed which increased the capacity and efficiency of the machine wonderfully. The most successful separator was designed by Dr. Gustaf De Laval of Sweden and the machines bearing his name are used all over the world where butter is made. But there are many other excellent separators on the market.

In the machine the milk is separated instantaneously by centrifugal force and runs out through two tubes, one for cream and the other for skim milk. A small modern hand machine will take care of from 200 to 1,000 lbs. of milk an hour, and power machines are built to separate 6,000 lbs. or more. By regulating the cream-outlet a heavier or lighter cream can be produced.

Suppose we are separating some milk containing 4% butter-fat. If ⅛ of this milk is separated out as cream and contains all the butter-fat, the cream will be eight times as rich in butter-fat as the original milk; 32% of the cream will be butter-fat. Such cream is called “32% cream.” If we take ¼ as cream, we get a cream four times as rich as the milk, a “16% cream.” So out of 100 lbs. of milk we can take 12½ lbs. (⅛) of 32% cream, 25 lbs. (¼) of 16% cream, etc.

Although the skim milk is really valuable as a food, it is worth but little commercially; the cream containing the butter-fat is the expensive part of the milk, and we must be prepared to pay for the cream all that the milk would have cost.

Percentage of Butter-Fat.—The “richness” of cream or milk and their value depend upon the amount of butter-fat in them. So cream or milk is often called “30% cream” or “20% cream” or “4% milk” according as 30% or 20% or 4% of the fluid is butter-fat; 30% cream is quite rich; ordinary market cream varies between 18% and 40%, though it may fall below 18%, or it may be sold as a very expensive article as high as 60%. Rich milk may contain more than 6% of butter-fat and skim milk less than 0.1 of one per cent. The average for good whole milk is between 3% and 4½%.

For a long time scientists and scientific dairymen were the only ones to speak of milk and cream in terms of percentage of butter-fat. Now, however, people are beginning to realize how valuable a part of the milk the butter-fat is and are paying more attention to the actual percentage of butter-fat in the cream or milk they use. So it is no longer unusual to see a dairyman advertise cream of a certain percentage or to hear a housewife ask for it specifically.

Standardizing Cream.—For ice cream or for preparing modified milk for babies, it is often desirable to dilute rich cream to a certain lower standard. The following simple steps can be taken to find out how much milk to add for diluting:

1. From the test—fat-percentage—of the rich cream subtract the test desired.

2. From the test desired subtract the test of the milk used for diluting.

3. Divide the first difference by the second, and the result will be the number of pints (or pounds) of milk to be added for each pint (or pound) of the rich cream.

For instance, you may want to thin some 30% cream to 10% for making ice cream. The milk to be added is skim milk. Then:

1. 30 - 10 = 20.

2. 10 - 0 = 10.

3. 20 divided by 10 = 2. So for each pint of rich cream you may add 2 pints of skim milk.

Or you may wish to thin the 30% cream with whole milk, which has 4% butter-fat. Again:

1. 30 - 10 = 20.

2. 10 - 4 = 6.

3. 20 divided by 6 = 3⅓. So you may add 3⅓ pints of the whole milk to each pint of the 30% cream and still have a 10% cream.

Pasteurized Cream does not look as rich as raw cream, and fresh, sweet cream appears to be thinner than when it is 24 hours old and slightly ripened. So it is well, when buying cream, not to judge by appearances. Demand of the milkman that he furnish you cream of a certain percentage of butter-fat and see to it that you get what you pay for. If you have no Babcock tester the milk inspector will test the cream for you.

Whipped Cream.—For whipping, cream must be fairly rich, from 24% to 32%, and it must be cold. Fresh, sweet cream does not whip as readily as that which has been kept for 12 or 24 hours in ice water. There is no other secret connected with the process. Use a rich cream, suitably cooled and aged, and with a good beater there can be no trouble in getting a fine, stiff whipped cream. If the cream is too thin or too warm it may not become stiff. Sometimes, when it is beaten too long, it turns into butter and buttermilk.

Emulsified Cream.—One of the recent additions to the already elaborate machinery used in the creamery, the milk supply or the ice cream business, is the Emulsifier. To be sure, emulsifiers were used thirty to forty years ago to mix animal and vegetable fats—oleomargarine oil, lard and cottonseed oil—into skim milk for “Filled Cheese” or for Butterine, but lately they are serving new purposes in the milk industry. By forcing melted butter-fat or oil mixed with water or skim milk through exceedingly small apertures under high pressure, or otherwise breaking up the mixture, an emulsion can be formed in which the fat globules are much finer even than those in natural milk or cream, and separation can be prevented. The force used in these emulsifiers may be produced by powerful pumps, or a steam jet, or centrifugal force under high speed; whichever system is used the machines answer the same purpose, to produce a permanent emulsion in which the oil or fat will stay in suspension even after cooling. In some milk supply plants and ice cream factories all the cream is emulsified and the system has especially been applied since the advent of the milk powder. It is now a not infrequent practice to run the new milk through the separator, make sweet, unsalted butter from the cream, and milk powder from the skim milk, and to ship or store these products separately where or until cream is wanted and then bring them together again by running them through the emulsifier with a suitable amount of water. At first thought this process would seem impractical and uneconomical. But it has proven good business because in many cases and places skim milk powder and butter keep better separately or can be shipped at long distance to better advantage than new milk or cream or condensed milk. In ice cream factories business may be dull in cold weather and cream is perhaps not provided and not available, when suddenly a hot spell brings orders for large quantities. With a stock of skim milk powder and butter on hand in the refrigerator, and an emulsifier to mix these products, cream can be produced on short notice and there will be no danger of shortage.

Ice cream has fast become the national dessert served on all festive occasions, winter and summer. Originally it meant a frozen mixture of sweetened and flavored milk and cream, but the name has long been applied to all kinds of frozen delicacies in which cream enters as a constituent. Not even there has the line been drawn, but gums, gelatine, cornstarch, eggs and other “fillers” have been substituted or added to thicken the mixtures and give “body” to “creams,” which have but little relation to the genuine emulsion of butter-fat from cow’s milk. Standardization has been attempted by National and State food authorities with varying success of enforcement. While the application of the name to a great variety of frozen desserts has no doubt become legitimate by long usage it may properly be demanded that as an article of merchandise “ice cream” shall contain at least 8% to 12% butter-fat and that no ingredients dangerous to health enter into its manufacture.

Freezers.—The freezing is usually done by contact of the material with metal cooled on the other side by a “freezing mixture” of salt and ice which produces temperatures far below the freezing point of water while air is whipped into the cream by the rapid motion of the beater. A great variety of excellent freezers of this kind for hand or for power are on the market which answer the purpose for making ice cream at home or at the ice cream parlor.

Coarse-grained salt and crushed ice, mixed in the proportion of 1 part salt to 4 parts of ice, are constantly filled into the space surrounding the ice cream can, and the brine produced by the melting of the mixture is gradually drawn off from the tub. In a good freezer the operation should not take over fifteen minutes. When the cream is frozen to a soft mush, stop the beater and scrape down the hard particles which may have accumulated on the sides of the can, add any ingredients which may be better incorporated at this stage than mixed into the original material, such as crushed fruit or preserves, and finish the freezing without carrying it too far.

Remove the beater, stir the cream which should still be soft enough to handle, and pack in ice with only a little salt. Or the cream may be transferred from the freezer can to the shipping can and packed in it. If bricks are wanted the soft cream is packed in molds of the desired shape and size and buried in the freezing mixture to harden.

In modern ice cream factories Brine Freezers are generally used. In a Refrigerator Plant intensely low temperatures are produced by the vaporizing of compressed ammonia or carbonic acid in an ice machine, and brine circulating in iron pipes is cooled by such medium and may, in turn, cool the air in the Cold Storage room, or the cream in the freezer, or pure water in metal boxes for the manufacture of Artificial Ice. It has been attempted to make the brine freezers continuous, the cream mixture being fed into the machine at one end and discharged frozen at the other. But this system has not so far been successful, and intermittent or batch freezers are most practical yet both for hand and for power.

Rich material, frozen in a good machine, whether intermittent or continuous, will expand from 50% to 100%, and the original material should not fill the freezer can more than half full.

The manufacture of ice cream has been the subject of study and experiments for years in the Dairy Department of the Agricultural College at Ames, Iowa, where Professor M. Mortensen has worked out a comprehensive classification from which any manufacturer may readily choose his formulas, modifying them to suit his local conditions and special problems. The outline kindly furnished the author by Professor Mortensen is so interesting and instructive as to be well worth copying substantially in full, leaving out the “Ices” in which no milk or cream is used and which are therefore not of special interest in connection with the purpose of this book—the use of more and better milk.

Considering the work of former writers as well as names used by business men, the following classification was worked out by the station:

Explanation and Formulas

I. Plain Ice Cream is a frozen product made from cream and sugar with or without a natural flavoring.

Formulas are given for making ten gallons of finished ice cream.

Vanilla Ice Cream:

Chocolate Ice Cream:

Maple Ice Cream:

Caramel Ice Cream:

Coffee Ice Cream:

Mint Ice Cream:

II. Nut Ice Cream is a frozen product made from cream and sugar and sound non-rancid nuts.

Walnut Ice Cream:

According to this general formula the following nut ice creams may be prepared by substituting different kinds of nut meats:

At times pistachio ice cream is made from oil of pistachio instead of from the nuts. If thus prepared, it will come under the head of plain ice cream.

III. Fruit Ice Cream is a frozen product made from cream, sugar and sound, clean, mature fruits.

Strawberry Ice Cream:

Employing the same formula the following creams may be made by merely substituting other fruits and berries for the strawberries. The amount of sugar may be varied according to the acidity of the fruit.

Preparation of lemon and orange ice creams cannot be included under this general rule. These creams may be prepared as follows:

Lemon Ice Cream:

Orange Ice Cream:

IV. Bisque Ice Cream is a frozen product made from cream, sugar and bread products, marshmallows or other confections, with or without other natural flavoring.

Macaroon Ice Cream:

From this formula we can make:

V. Parfait is a frozen product made from cream, sugar and egg yolks with or without nuts or fruits and other natural flavoring.

Walnut Parfait:

From this formula by substituting the nut meats we can make:

By substituting the same proportion of fruits as are used for fruit ice cream, for the vanilla extract and nut meats, fruit parfaits such as strawberry, raspberry and cherry parfaits and others may be prepared.

Coffee Parfait:

Maple Parfait:

Tutti-Frutti:

VI. Mousse is a frozen whipped cream to which sugar and natural flavoring have been added.

Cranberry Mousse:

From the same formula combinations may be made with various other fruit juices and natural flavors, such as coffee, vanilla, maple, caramel, pistachio, etc.

Sultana roll, as indicated by the name, is made in a round mold. The center of the mold is filled with tutti-frutti, and the outside with pistachio mousse.

VII. Pudding is a product made from cream or milk, with sugar, eggs, nuts and fruits, highly flavored.

Nesselrode Pudding:

Manhattan Pudding:

Plum Pudding:

VIII. Aufait is a brick cream consisting of layers of one or more kinds of cream with solid layers of frozen fruits.

Fig aufait may be made from three layers of cream of various flavors with two layers of whole or sliced figs. It is most satisfactory to slice the figs lengthwise in halves.

Other aufaits may be made from a variety of preserved fruits and berries and combined with different creams.

IX. Lacto is a product manufactured from skimmed or whole sour milk, eggs and sugar, with or without natural flavoring.

Formulas for lactos may be found in Bulletin No. 140 published by the Ames Station.

As an example, the following mixture will make 5 gallons of

Cherry Lacto:

“Lacto Milk” is the same as described under “Commercial Buttermilk” and “Thick Milk,” pages 81 and 82.

The sugar is first dissolved in the lacto milk. The eggs are then prepared. The whites and yolks are kept in separate containers and each lot is beaten with an egg beater. Both the yolks and whites are then added to the milk. The mixture is thoroughly stirred and strained through a fine wire gauze. The fruit juices are added last. The freezer is now run until it turns with difficulty when the paddle is removed. The brine is removed and the freezer repacked with ice and salt and left for an hour before the contents are served.

Orange, Mint, Pineapple, Maraschino, Raspberry or Grape Lacto may be prepared by substituting any of these flavors for the Cherry.

X. Ices are frozen products made from water or sweet skimmed or whole milk, and sugar, with or without eggs, fruit juices or other natural flavoring.

Ices may be for convenience divided into sherbets, milk sherbets, frappes, punches and souffles.

Milk Sherbet is an ice made from sweet skimmed or whole milk with egg albumen, sugar and natural flavoring, frozen to the consistency of ice cream.

Pineapple Milk Sherbet:

Milk sherbets of various flavors may be prepared according to above formula by substituting other flavorings.

The formulas presented above have been given mainly for the purpose of making clear the difference between the various groups. Numerous other formulas may be prepared on the same general outline.

Prof. Mortensen’s formulas are mostly made out for ten gallons of ice cream. It is hardly necessary to call attention to the fact that they can easily be adapted to any smaller quantities by reducing each of the ingredients alike. For instance, to make:

1 gallon of Plain Vanilla Ice Cream, divide the figures given above by 10 and use: