Elements of the theory and practice of cookery

170. Its food value. — Milk is seen to contain one or more of each of the chief kinds of foodstuffs, tissue- building, heat-giving, and strength-giving ; besides water and mineral matter. For the calf it is a perfect food, and almost perfect for a human baby. For older people, however, it is not a well-balanced food, i.e. these foodstuffs are not in the right proportions. There is not enough sugar to give the strength a grown man needs for his work, and there is so much water that he would have to drink an enormous quantity of milk to obtain the necessary quantity of foodstuffs. 1 The albumin is in true solution, the casein in partial solution only. In this state it is called by chemists caseinogen (casein-maker). 2 It can be so toughened as to resemble celluloid, in which state it is made into buttons and similar articles. 94 THEORY AND PRACTICE OF COOKERY Mention some foods commonly eaten with milk. What foodstuff or foodstuffs, lacking in milk, do these foods supply ? Remember that milk is food, not drink merely ; less of other food is needed at a meal with which milk is drunk. Drink it slowly. It is more readily digested when taken in sips. 171. Buying milk; dangers of cheap milk. — Good milk is a yellowish white, opaque liquid, having a slightly sweet taste. It should have no sediment and should not look blue around the edges. Skim milk sells for about one-half the price of whole milk. It is, of course, poor in fat, but is richer than whole milk in casein and albumin, and may be used instead of it for many pur- poses in cooking. Skim milk is far more desirable and economical than so-called whole milk sold at less than the regular market-price. This is likely either to be of poor quality, perhaps colored to make it look rich, or to be watered, in which case a quart of it may contain no more nourishment than a pint of " honest " milk. 172. Care of milk. — Milk quickly absorbs tastes, odors, and impurities. It is more liable than almost any other food to contain disease germs. From the time it is drawn from the cow it should be kept in clean vessels (glass, earthenware, or bright tin ; not wood), in a cool, clean place. Otherwise it rapidly sours, and sometimes undergoes changes that make it actually poisonous. Milk sold from open cans in cities is more likely than bottled milk to contain dirt, and to sour quickly. TISSUE-BUILDING FOODS: EGGS AND MILK 95 173. Scalding milk. — To make sure that milk is safe for use, especially for children, who are most likely to be made sick b}^ impure milk, scald it (i.e. heat it to about 160° F.). This is best done in a double boiler. ^ When small bubbles appear at the edge of the milk it is scalded. Use when cool. Boiling makes it less di- gestible. What substance in the milk should never be heated to the boiling-point ? Explain why milk tum- blers should not be put directly into hot water. A Study of Milk {continued) 174. Souring of milk. — F. Examine sour milk. Notice the separation of the curd from the whey. What* substance, added to milk, makes it separate like this ? Taste the sour milk. Does it taste at all like vinegar?