Page:The Boston cooking-school cook book.djvu/31

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The value of milk as a food is obvious from the fact that it constitutes the natural food of all young mammalia during the period of their most rapid growth. Milk should constitute the principal protein food of children. It is rich in calcium (which is necessary for the building of bones) and vitamines (growth-promoting substances). Adults as well as children should be furnished a liberal milk supply. A quart for each child and a pint for each adult, daily, is a desirable allowance. Hot milk is often given to produce sleep.

When milk is allowed to stand for a few hours, the globules of fat, which have been held in suspension throughout the liquid, rise to the top in the form of cream; this is due to their lower specific gravity.

The difference in quality of milk depends chiefly on the quantity of fat therein: casein, lactose, and mineral matter being nearly constant, water varying but little unless milk is adulterated.

Why Milk Sours. A germ found floating in the air attacks a portion of the lactose in the milk, converting it into lactic acid; this, in turn, acts upon the casein (protein) and precipitates it, producing what is known as curd and whey. Whey contains water, salts, and some sugar.

Milk is preserved by sterilization, pasteurization, and evaporation. Fresh condensed milk a form of evaporized milk, is sometimes sold in bulk, and is preferred by many to serve with coffee. Various brands of condensed milk and cream are on the market in tin cans, hermetically sealed. Examples: Nestle's Swiss Condensed Milk, Eagle Condensed Milk, Daisy Condensed Milk, Highland Evaporated Cream, Borden's Peerless Evaporated Cream. Malted milk —evaporized milk in