FoodNet

Foods, their selection and preparation

1935

Page 105

Presented as published in 1935. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
Fat is present in milk in the form of small globules, each surrounded by a film of pro¬ tein. This film prevents the globules from coalescing, and keeps them in suspension. Fat distributed in a liquid in this way is said to be in the form of an emulsion. Under the microscope these small droplets of fat can be seen. In cream they are much closer together than in whole milk. In skim milk only occa¬ sional fat globules appear. The fat in milk from Holstein cows is distributed in smaller globules than that in Jersey milk. The size of the globules in the milk from the other breeds varies between these two extremes. Holstein milk is recommended for infant feeding since the small fat globules are easier to digest. The pigment which gives the color to cream and butter is soluble in the fat. The amount present varies both with the breed of cow and with the amount of green food which the animal consumes. Table XXIV • Time Required ANIMAL TIME RE¬ QUIRED TO DOUBLE WEIGHT COMPOSITION OF MILK Protein Total Ash Calcium P205 for Young Animals Days Per cent Per cent Per cent Per cent to Double Weight Human . 180.0 1.4 0.2 0.0328 0.0473 47.0 3.4 .7 .1600 .1970 and Amount 19.0 3.3 .7 .2100 .3220 of Tissue-forming Foods Sheep . 10.0 5.5 .9 .2720 .4120 in the fljpther’s Mill 9.5 7.0 1.0 Dog . . * 8.0 7.3 1.3 .4350 .4930 [113] Homogenization. When the fat globules in the cream layer of milk are too large, they tend to run together and separate as an oily layer. This separation can be prevented by homogenizing the milk. In this process the milk or cream is forced through small pores in a diaphragm under very high pressure at a temperature of 167° F. This breaks up the fat into very small globules of uniform size and distributes them in the solution of milk proteins. These proteins coat each drop of fat, forming a stable emulsion. When the globules are very small, they tend to remain uniformly distributed through the milk so that the cream does not rise on homogenized milk. It is possible, by homogenization, to redis¬ tribute butter in skim milk to form either whole milk or cream. Since butter keeps much better than cream, milk fat is some¬ times stored in this form and redistributed in milk later when a supply of cream is needed to meet an unusual demand. Market Forms. On the consumer market, cream and whole milk are available in fresh fluid form, in bottles or paper containers. Either may be obtained homogenized. But¬ termilk and skim milk also are available in fresh fluid form. Condensed and evaporated milk are available in cans. Dried whole milk, dried skim milk, and dried buttermilk are available to wholesale consumers, and in some markets are available through retail channels. COMPOSITION AND NUTRITIVE VALUE Composition. Milk contains more of the nutrients known to be essential to health than any other food. It is especially useful as a source of calcium, riboflavin, and efficient protein. While the composition of milk from different herds varies, its average proximate composition is as shown in the table. Composition Water . . 87 per cent Protein . . 3.3 per cent of Fat . . 4 per cent Milk Carbohydrate . . Minerals .... . 5 per cent .7 per cent