When milk is soured by any form of acid, it coagulates; the casein is eliminated and cheese is formed. Salting and ripening are not really necessary features in the making of cheese, as there are some varieties of cheese, such as the Gervais, or fresh-cream cheese, for example, in which these processes are not resorted to.
For the wholesale and rational, cleanly manufacture of cheese, rennet is used. Young animals, such as calves, goats, and lambs, have much pepsin (rennet) in the mucous membrane of their stomachs, from which it can be removed with common salt, thus forming an extract. When a small quantity of this liquid extract is added to milk which has previously been heated to about 300 or 350 C., the milk will, after a time, coagulate. The cheesy substance is then pressed and molded, and is afterward salted. The quantity of salt added varies according to the nature of the cheese being made. The cheese is then placed in cellars and is allowed to ripen,a species of fermentative process caused by bacterial action. The nature of the cheese depends not only upon the good quality of the milk, but also upon the kind of bacteria which are acting upon it during the ripening process. A great variety of schizomycetes, or fission fungi, as well as many yeasts and hyphomycetes, or mold fungi, are active in the transformation. In many of the Dutch cheeses, such as Gouda, Limburger, etc., there is no yeast. During the fermentation process gases are developed, especially carbonic acid gas, and when they disappear holes in the cheese remain. In the making of 1 kilo of cheese, 10 or more liters 0f milk are required.
The different varieties of cheese are produced according as sweet or sour milk, cream, or skim milk or whole milk is used, as well as according to the pressure exerted and the quantity of water which the milk still contains.
Gervais and various cream cheeses are made from cream, or whole milk and cream, and are either not pressed at all or only very slightly so. Some cheeses, as the Gervais and cream cheese, are not subjected to any ripening, or they may be ripened like the Neuchâtel, Brie, Strachino, Hagenberger, and Schwarzenberger varieties, or like the MacLaren Canadian cheese, so well known in England and America. These cheeses are distinguished by the fact that they contain a great deal of fat, which exceeds the quantity of albumin.
Soft cheeses made from whole milkthe fatty cheeses so greatly used by us, namely the Brimsen, Liptauer, and Siebenbürger varietiesare all made from sheep’s milk.
Hard cheeses are subjected to heavy pressure, and in their preparation the milk is first cooked. From fat-containing milk the Emmenthaler, Edam, Chedder, and Chester cheeses are made; the Roquefort, another rich cheese, is made from sheep’s milk. From semifat milk-the whole milk of the morning milking and the skimmed evening milk-Gruyère and Parmesan cheeses are made.
The varieties containing the least fat are the Danish export cheese, the Swedish kummel cheese, and those made from sour milk or buttermilk, such as the Mainz hand cheese, Topfen, and Quargeln, and the cheeses made from whey.
The chief characteristic of cheese as a food is that it probably possesses the highest nutritive value of any, and also offers the most albumin, exceeding in this respect meat and the most nourishing among the vegetable foods. When we remember that with i kilo of cheese we obtain 3808 calories we are surely justified in considering it the most nourishing food, since, moreover, it contains the three main elements of our nourish-ment. If an adult person takes during a day / kilo of rich cheese, % liter of milk, a large piece of white bread, and sufficient butter for the latter, he will have a full ration, and there is probably no mode of nourishment which is more wholesome and less injurious for the various organs of the body. Cheese, notwithstanding its great nutritive content, does not lead to the formation of uric acid, nor does it irritate the kidneys or the liver, if the kind used is not too old. Old cheese certainly does not possess the hygienic properties of fresh, soft cheese ; but it is often more easily digested, its albumin content having become peptonized. It may sometimes, however, contain sub-stances having a toxic action, as has been shown by Vaughan.
For a healthy person cheese is an easily digested food, and it is also very well assimilated. It assists in the digestion of other foods; thus, macaroni is more readily digested when a finely grated cheese, e.g., Parmesan, is sprinkled over it ; the same is true in the case of Indian corn (Kukuruz). While cheese is well digested by a healthy stomach, the case is quite different where this organ is weak. In such conditions it is better to forbid the use of cheese, for the fat, especially in hard cheeses, is digested with difficulty, and even the albumin is not easily acted upon by the gastric juice, since it is surrounded by fat. The fat contained in the fresh, soft varieties of cheese should, in general, be more readily digested. Fatty cheeses of the nature of Gervais may be advantageously used where there is overacidity of the stomach; but not the old cheeses, especially Edam or similar varieties. Great care must be taken that the soft cream cheeses, such as Gervais, are perfectly fresh, for rancid cheese is very apt to cause digestive disturbances. Just like fresh, unsalted butter, the unsalted cream cheese does not keep well, and must be used when quite fresh. When one has very good teeth, and thoroughly masticates the hard cheeses, they are not so hard to digest. In order to assist the digestion of cheese, it would be well to follow the advice of Robert Hutchison, viz., to take as much bicarbonate of soda. as will cover the point of a knife with every quarter-pound of cheese.
Cheese may be especially valuable when it is taken in addition to a vegetable diet, since but little albumin is obtained from the latter, a fact which may bring about dangerous results. These will be described in another portion of this work.