Milk contains all the food-stuffs which the body requires, except
starch, and, therefore, is capable of sustaining life for comparatively
long periods. It is one of the most important protein foods; but it
contains so small a percentage of carbohydrate (milk sugar) that for the
adult it must be supplemented with carbohydrate foods. For the baby,
milk is a perfect food, and it is a valuable adjunct to the diet of all
children. One quart of milk should be allowed for the diet of each child
daily, after the twelfth month; and the diet of the adult should be
supplemented by the use of milk. The greatest care should be exercised
in protecting milk from dust and dirt, for it is easily contaminated and
may be the means of carrying disease germs to the body. The changes
which milk undergoes when souring do not render it harmful. For many
people buttermilk is more easy of digestion than sweet milk, because of
the changes produced by souring, as well as the absence of fat. Sour
milk is of value in cooking, producing a tender bread which can readily
be made light by the addition of soda--one teaspoonful of soda to one
pint of sour milk that has curdled.
In the preparation of cheese, the whey is separated from the curds, thus
extracting most of the water, sugar, and mineral matter, and leaving a
substance rich in protein and fat. Cheese is of value in cooking, for it
increases the food value of those foods to which it is added.