The various industries connected with the use of fresh milk or its products are among the earliest and most important in the history of civilization. The lack of mammals which could be ' domesticated and which would yield milk in captivity was one of the greatest handicaps of the American continent as compared with the old world, not only in preventing agricultural and industrial development but in increasing the mortality of infants and adults in a state of disease or weakness requiring readily digestible food.

The insurance of a good milk supply involves the following main points:

1. Efficient general inspection of herds to prevent tuberculosis and to secure condemnation of tuberculous animals; also to detect local disease of the udders and appendages, to regulate breeding, transportation and feeding and housing of cattle or other milch animals.

2. Similar inspection, mainly by local municipal governments, to assist in the same items and to insure cleanliness and prompt delivery of properly sealed containers.

3. Ordinary cleanliness and care in handling animals, milking and in other details.

4. Prompt refrigeration of milk in a dust-free place, immediate bottling under reasonable aseptic precautions, continuance of refrigeration until delivery and, by domestic management, till used. In spite of such precautions, milk should be used as soon as possible after being drawn. Under ordinary conditions, it is possible to deliver milk in sealed containers, at a retail cost of five or six cents a quart, and with a bacterial content of not over 10,000 per cubic centimeter. Even when sold at fancy prices by hygienic dairies, lapses in care may cause a rise of bacteria to 100,000 per cubic centimeter.

5. General and local inspection should also be practiced to avoid accidental contamination with germs of typhoid, etc., from water used to wash receptacles or with various other specific germs due to sickness in the family of the milkman and other local causes.

Milk mixed from a number of cows is more likely to conform to the average standard. Chances of infection are mathematically increased but, on the other hand, the degree of infection is likely to be less than when a lapse occurs in the handling of one cow's milk. Provided that systematic inspection is fairly adequate, mixed milk is generally preferable to milk of one cow, even for infant feeding.

Comparative Composition Of Different Milks. - Blythe

Providing that care is taken to exclude infection, clean raw milk is superior to sterilized, Pasteurized or preserved milk of any kind.

Condensed milk is of two kinds, one consisting merely of fresh milk, partially evaporated at a temperature sufficient to secure sterilization, and sealed. Such milk analyses about as follows:

The stronger condensed milks are evaporated to 1/4 or less of the original .bulk, with corresponding increase of the various solids and with or without the addition of cane sugar, as a preservative. Thus, the proteins, fat and lactose will amount to 15 - 25% each, the salts to 3 - 5% and the added cane sugar usually 20 - 50%.

Completely evaporated milk has been prepared on a small scale as a powder by spraying milk into a hot-air chamber. Unfortunately, the fat tends to melt and to become rancid and physicians are warned against investing in enterprises of this sort unless proved to be practical on a commercial scale. Recently, powdered milk and cream have been placed on the market at prices relatively not much higher than fancy grades of fresh milk. The powdered milk keeps for several weeks, but the cream tends to become rancid and to cohere.

Cream is merely the lighter stratum of milk that has been allowed to stand or has been centrifuged to expedite the action of gravity. According to richness, it contains 20 - 35% of fat and slightly less protein and lactose than milk, about 3 - 3.5%. Condensed cream is also prepared. Clotted or Devonshire cream is skimmed from milk curdled by heat and may be variously flavored with aromatics, combined with eggs, sugar, etc. Whipped cream may be added to fruits, gelatin preparations, etc.

Ice cream theoretically consists of pure cream, sweetened, flavored and frozen, but as made commercially, it usually contains considerable milk and wheat flour, corn starch, etc., or gelatin or eggs are added to increase its consistency. Its food values must, therefore, be computed from the individual recipe employed. A good formula is: Milk 20 parts, Cream 60 parts, Sugar, by weight, 30 parts, Wheat flour, by weight, 1 part rubbed up with enough milk or water to make a paste, Vanilla, chocolate paste, etc., enough to flavor; about 1 whole egg to the pint.

Under certain conditions, not well understood, but according to Victor C. Vaughan, requiring infection with colon bacilli, various milk products and especially ice-cream and creams mixed for pastry fillings, are liable to develop tyrotoxicon and to be dangerous to life. The bacterial activity is not necessarily or even usually attended with obvious fermentative or putrefactive changes, so that there is no warning of the danger aside from the probability or definite knowledge that the milk products are not prepared in a cleanly way or that they have been kept too long.

It should be clearly understood that tyrotoxicon poisoning does not necessarily occur in groups, as at picnics, etc., that there are marked individual differences of susceptibility and that this or some similar poisoning by milk may occur in a mild, protracted form, in infants, typhoid patients and others. Tyrotoxicon poisoning, at least in typic degree, is not especially likely to occur from milk foods subjected to prolonged fermentation, as buttermilk and cheese and it is rarely possible to trace it to butter although it is perfectly possible that many conditions of alimentary saprophytosis may be due to butter.