in the household; in 1920, about 350,000,000 pounds, of which 98 per cent was made in factories.

About two thirds of this cheese was made in Wisconsin, the larger part of the remainder in New York, while small amounts were contributed by several other states, including (quite recently) some of the mountain sections of the South.

Including that imported, the total cheese consumption in the United States is only 3 to 4 pounds per person per year, a low figure in comparison with the amounts of meat and butter consumed. During the past few years the United States Department of Agriculture has given considerable attention to the cheese industry and to the use of cheese as a food, and it is probable that this will result in a larger per capita consumption of cheese for the country as a whole.

Cheese is roughly divided into two main types: the hard cheeses such as Cheddar, Edam, Emmental (or Swiss), Parmesan, and Roquefort; and the soft cheeses such as Brie, Camembert, Gorgonzola, Limburg, Neufchâtel, and Stilton.

Much the largest part of the cheese made in this country is of the type of the Cheddar cheese and is therefore properly known as American Cheddar cheese, although frequently called simply" American cheese " or, in the trade," standard factory cheese." In addition to this standard type of cheese smaller quantities of other types are made. Some New York factories make cheeses of the Brie, Camembert, and Neufchâtel types, while cheeses of the Swiss and of the Limburg types are made in Wisconsin and Swiss cheese in California.

The principal importations of cheese into the United States are of Parmesan and Gorgonzola cheese from Italy; Emmental cheese from Switzerland; Roquefort, Camembert, and Brie, from France; and Edam cheese from Holland. Many other varieties are imported in small amounts.

Exportations of cheese from these countries were naturally much reduced during the war. In fact from 1915 to 1918 Amer

ica exported more cheese than it imported. Since the war, both imports and exports have been small, the American market being supplied essentially by cheeses of American manufacture, among which those of the Cheddar type predominate, while other types are growing in importance as the methods of making them are improved.

Manufacture of American Cheddar Cheese

This process is divided into several fairly distinct steps as follows: (1) inspection of milk, (2) ripening of milk, (3) addition of color - when color is used, (4) coagulating the milk, (5) cutting the curd, (6) stirring and heating the curd, (7) removing whey, (8) cheddaring the curd, (9) milling the curd, (10) salting and pressing the curd, (11) ripening or curing the cheese.

Inspection of milk. Each can of milk received for cheese making should be examined for acidity, dirt, and abnormal flavors (odor or taste). Sometimes a rapid examination by the senses of sight and smell is deemed sufficient; sometimes a roughly quantitative determination of the acidity is made. When the cheese maker is troubled with abnormal fermentation or defective curd, it may be necessary for him to make a test of each farmer's milk to determine the nature of the fermentation which it shows and of the curd which it yields, in order that the particular milk which is responsible for the trouble may be located and excluded.

Ripening of milk. This consists in keeping the milk at about 86° F. (30° C.) until the desired amount of lactic acid has formed. Starters," consisting of commercial cultures of lactic acid bacteria or of milk in active lactic acid fermentation, are sometimes added to facilitate the ripening process. The lactic acid is important in its influence on the operations of cheese making, and its presence also tends to repress abnormal fermentations. The proper degree of ripeness is judged either by titrating for

acidity or by testing a portion of the milk with rennet to see whether it coagulates as readily as is desired. Acidity equivalent to 0.20 per cent of lactic acid usually marks the completion

of the ripening process.

Addition of color. When coloring matter is used in cheese making, it should be added to the ripened milk just before coagulating it with rennet.

Coagulating the milk. Rennet is the most useful reagent for the precipitation of the curd, that prepared from the calves' stomachs being most highly prized for cheese making. Rennet is now prepared on a large scale and is purchased from the makers for use in the cheese industry. The quality of the rennet is very important, as an inferior grade gives a bad taste to the cheese. The amount of rennet to be added depends, of course, upon the strength of the preparation, but should be sufficient so that when mixed with the milk and kept at 84°-86° F. the milk will be curdled in 15 to 20 minutes if it is to be used for a quick-curing cheese, and in 30 to 40 minutes for a slow-curing cheese. The rennet extracts commonly used are added in the proportion of from 2 to 5 ounces per 1000 pounds of milk. Before adding, the extract should be diluted with 40 times its volume of water at a temperature of 85°-90° F. so as to prevent the production of a lumpy curd. Previous to adding the rennet the milk is thoroughly stirred in order to distribute the fat evenly, and the rennet is added evenly and slowly with constant stirring, which is continued for several minutes. After this, the milk is stirred gently near the surface to prevent separation of cream. All stirring is stopped as soon as (or before) coagulation begins, and the milk is then left covered and undisturbed while the coagulation gradually continues until the whole mass forms one coherent curd and is ready for cutting.

Cutting the curd. In order that the whey may be separated it is necessary that the curd be cut into pieces; the smaller the pieces of curd, the more rapidly will the whey escape. As soon

as the curd is formed it tends to contract and force out a portion of the whey. By cutting the curd the surface from which the whey can exude is increased and so the separation of the whey from the curd goes on much more rapidly. The time for cutting the curd is important and is determined by the skill and experience of the cheese maker. If the curd is cut when it is too soft, there may be a large loss of fat, with a resulting decrease in the yield and quality of the cheese. If the curd is allowed to become too hard before cutting, the whey is removed with greater difficulty; and if incompletely removed, a cheese of low quality results. The cutting is accomplished by drawing specially devised cutting knives through the mass of curd, both horizontally and vertically, so as to cut it into cubes of one quarter to one half inch size.

Stirring and heating the curd. As soon as the curd is cut, the whey begins to separate, and the mass of cut curd is then kept in gentle motion by stirring, taking care to avoid breaking the cubes. This results in the separation of a clear whey, free from fat or small particles of curd. The curd contracts and hardens during this process and soon reaches a condition in which the surfaces do not readily adhere. During this process of separation of the whey, the temperature is raised to about 90° F. and finally toward the last to about 98° F.

Removing the whey. The precipitated curd is left in contact with the whey for some time, during which time there is some action of the acid of the whey upon the protein of the curd, which is allowed to continue until a small mass of the curd, which has been squeezed in the hand to remove the whey and then pressed against a bar of iron heated a little below redness, will leave adhering to the iron fine, silky threads, the length of which indicates roughly the extent to which the desired combination of acid and protein has taken place. Usually the curd is separated when the hot iron test shows strings about one eighth of an inch long; but other tests are also used to aid in judging when the

whey should be removed. The whey is run off gradually while the stirring of the curd is continued.

Cheddaring the curd. Most of the whey having run off, the cubes of curd are left piled in the bottom of the vat until they mat or pack together, which process is technically known as "cheddaring." Sometimes the "cheddaring" is accomplished in a special apparatus called the "curd sink." When the cheddaring of the curd is complete, it is cut into blocks, 6 to 12 inches in each dimension, which are turned in the vat in order to facilitate the further removal of whey, and are then carefully placed, one over the other, until they form a large mass. The process of solidifying or "cheddaring" has two results: first, the more complete removal of the whey, and second, the formation of a characteristic texture in the curd which becomes less rubberlike and more velvety and forms strings of an inch or more in length when tested with the hot iron. During the cheddaring a considerable increase of acidity occurs, the last of the whey which drains from the piled curd showing usually an acidity equal to 0.6 to 0.9 per cent of lactic acid.

Milling the curd. The milling process consists in cutting the lumps of curd into small pieces of uniform size in order that it may be salted more evenly and handled more readily when it is placed in hoops for pressing. This is done by means of curd mills designed to avoid as far as possible the loss of fat which would result from crushing or squeezing the curd.

Salting and pressing. Salt is added chiefly for flavoring, but also it aids in removing the whey, it hardens the curd, it checks the further formation of lactic acid, and it helps to prevent the development of undesirable fermentation. Excessive salting is, however, injurious. Usually from 1 to 3 pounds of salt are added to the curd obtained from 1000 pounds of milk. After filling the curd into the mold it is pressed in the proper form by a uniform pressure which is continued for 24 to 48 hours. Usually a light pressure is applied at first and gradually increased