CHEESE-MAKING. The making of Ched da• cheese, which is the common cheese made in the United States and Canada, and also exten sively in England. may be taken as illustrating the general principles upon which the proves; depends. The milk used should lie free from taint 1 r sun di, and of good quality as regards composition. ‘Chile the casein of the milk is the part width is curdled and gives the body to the (cheese, the fat is an important constituent of the finished product, and it has been conclu sitTly shown that the cheese-produchug power of milk is measured by its percentage of fat. !fence the fat content of milk indicates its value for both cheese and butter making. The casein in milk exists in a state of semi-solution, from vvblch it is separated or curdled by acids, as in the case of sour milk, or by rennet extract pre pa•.d from the stomachs of young mammals, usu ally calves. The latter is most t•numonly used for producing the curd, as the curdled (casein is called. The fresh milk is first ripened to the proper degree—i.e. a certain amount of lactic acid is developed in it by keeping it for a short time at about S5' F. The acidity accelerate. the action of the rennet. When the milk is sufficiently ripe. the rennet is added in diluted form and stirred in, the milk being held at from S2° to SO° F. Ten or fifteen minutes are re quired to carry the curdling to the proper stage, after which the curd is cut into small pieces with gangs of steel knives, in order to faeili tate the emdraction of the curd and the ex pulsion of the whey. The mass is then stirred gently for about live minutes, and subsequently heated to about 9S° or 100°, the result being the formation of more acid and a further shrink age of the curd. The object in these operations it to separate the whey from the curd with the least possible loss of fat. Most of the fat. is inclosed in the curd mechanically, but some little goes into the the amount depending upon the skill of the operator. When the curl has assumed the proper consistency (usually judged by its stringing oat in little threads when touched with a hot iron). the whey is drawn MT
and the curd is allowed to unit together into a solid mass. This is cut up into blocks, which are turned so as to maintain a uniform heat throughout. The development of acid. which continues. changes the character of the curd, and when the hot-iron test shows threads 2 or 3 inches long the eurd is ground, or, more properly speaking, cut. and salted, the salt hardening the enrd and checking the further development of acid. It is then pressed to bring it into suit able form and remove any surpIlls whey. After this it is ripened in rooms or cellars kept at a temperature not above 65° or 70° for several weeks, and even months. This ripening is an important and critical part of the process, and has much to do with determining the general quality and character of the cheese. In it the casein is peptonized and changed to forms which are digestible, and the characteristic flavors are developed. If the temperature of the curing room is too high. the cheese ripens rapidly, but gets oil' flavor and even spoils: and if the air is too moist, the cheese molds. Low temperature and slow curing are much the safest methods, since they favor the making of cheese of the best quality.
The losses in cheese-making occur in the whey and in drippings from the •heese-press. The albumin, a milk constituent similar to casein, is not coagulated by the rennet, and passes into the whey. This is true also of the milk-sugar. only a little being carried into the curd. The fat of the milk is quite largely (all but 5 or 10 per cent.) recovered in the cheese in careful making. The amount of cheese that can be made from I00 pounds of milk depends upon (1) the skill of the maker. (21 the amount of water left in the cheese, and (3) the composition of the milk. As mentioned above, the richer the milk is in fat, the greater the amount of cheese that can be made from it hut with poor making this increase of fat in the milk may very easily be lost.