Cheese, so far as nutritive value is concerned, stands almost at the head of our list of foods. Since it is made from the curd of the milk, and the water has largely been disposed of in the whey, while the fat is carried down with the curd, we have the most important part of the milk solids in a condensed form. The composition of the different varieties of cheese varies to quite an extent, but in a rough way we may say that cheese is one-third proteid, one-third fat and one-third water. Mineral salts are abundant as well, while a small amount of milk sugar is sometimes present.
Cheese is prepared by the addition of rennet to milk. Coloring matter is generally added, and salt. After the curd has set, it is cut in small pieces and the whey allowed to drain off. The curd is then put into a press and allowed to remain for a few hours. After this the real curing or ripening of the cheese begins, and this process is allowed to go on for months in order to develop the flavor. This flavor is produced by the action of bacteria, different varieties of bacteria giving us the different flavors of the various kinds of cheese.
While there is no question as to the nutritive value of cheese, there is more doubt as to its digestibility. In many countries cheese is used largely as a substitute for meat, and wherever it can be digested this is certainly a rational thing. Some people who have delicate digestions have no difficulty in digesting cheese, while others find it an extremely indigestible food. One difficulty seems to be that the cheese is frequently not chewed enough, and the digestive organs have to cope with lumps of the material.
Cheese generally proves more digestible if it is finely divided and mixed with some starchy material like bread crumbs or macaroni. Another factor in its digestibility is the temperature at which it is cooked. Like all proteid foods, it is toughened and hardened by a high temperature. This is very evident in the case of such a dish as a Welsh rarebit, where over-cooking produces a tough, stringy, most indigestible mass. In combining cheese with such a dish as macaroni it is well not to allow the cheese to be at the bottom or the top of the dish, but to protect it from the high temperature by putting it between the layers of starchy material.
Matthieu Williams, in his chemistry of cookery, suggests the use of a little bicarbonate of potash, the old-fashioned salaratus, to make the cheese more soluble and therefore more digestible. Sometimes after the cheese has become tough from the action of too high a temperature, it may be again made soft by the addition of this substance, or of baking soda. Hutchison suggests that the disagreeable effect that cheese has upon some people may be due to small quantities of fatty acids produced in the process of ripening. The philosophy of the use of cheese at the end of a dinner seems to be that the cheese in small quantities aids the digestion of other foods, even though it is not always easily digested itself. Wherever, then, cheese can be used and digested without difficulty, it forms an excellent article of food, one that should be used more freely than is done at present.