The yield of cheese from milk is, directly influenced by the per cent of fat it contains, This is shown by the following table; It will be seen that the yield of cheese in creases with the per cent of fat in the milk, the increase, however, being not directly pro portional to the increase in fat because the casein does not increase as rapidly as the fat. The quality of the cheese which can be made from any given lot of milk depends very largely upon the care it has received. Clean milk is the first essential for successful cheese making, and great care should be used not to take in milk having high acidity or bad flavors or odors or showing visible dirt. Any of these conditions indicate the presence of certain types of bacteria which will injure the quality of the finished product. After milk of good quality has been obtained, the first step is to develop the proper degree of acidity. This may be done by allowing the milk to stand at a temperature favorable to the growth of the lactic acid bacteria, or the process may be hastened by using an artificial starter, as in the making of butter. As •soon as the desired degree of acidity has developed, the rennet should be added. The amount to be used, as given by Publow, depends on (I) the strength of the extract ; (2) the temperature of the milk; (3) the acidity of the milk; (4) the composi tion of the milk; (5) the kind of cheese to be made, and (6) the temperature of curing. In general, an amount sufficient to coagulate the milk fit for cutting in 25 to 35 minutes should be used; generally from 21/2 to 4 ounces for 1,000 pounds of milk will suffice.
When the milk is well coagulated, small wire knives designed for the purpose are used to cut it into small cubes to allow the whey to escape. It is important that the expulsion of the whey and the firming of the curd should be carefully controlled, which is done by stirring the curd and by the application of heat. When the little cubes of curd have contracted to slightly less than one-half their original size and are firm and rubber-like, the whey is drawn off from the vat. As soon as the whey is sufficiently removed the curd is piled along either side of the vat 'and allowed to drain thoroughly; after it is well matted it is cut into strips which may be piled to any desired depth to hasten the further removal of the whey. This cheddaring process is continued till the curd shows the desired texture and the whey coming from the curd has the required degree of acidity. The curd is now °male& by running it through a machine which cuts it into small, even sized pieces in order to further assist in the escape of the whey and make the salting process easier. The curd is then spread over the bottom of the vat, the salt sprinkled over' the surface and the curd is stirred to insure the even distribution of the salt to the surface of each piece. The chief purpose of the salt is to improve the flavor of the finished cheese; it may also assist in the removal of whey and the control of acid de velopment. It is now ready to be put into proper form for marketing by placing the loose pieces of curd in metal hoops and subjecting to sufficient pressure to cause the pieces of curd to adhere to each other firmly. American Ched
dar cheese is placed upon the market in a num ber of forms or styles as is indicated by the following table:* Cheese of the Cheddar type requires consid erable time for the development of the charac teristic flavor. When first made the texture is tough and rubbery, and there is little cheese flavor or aroma, but in the course of a few months chemical and biological changes take place which give the cheese a soft, smooth tex ture and its characteristic aroma and flavor. Not all the changes occurring during this ripening process are well understood, but it is known that they are largely the result of bac terial action and that the Bact. lactic acidi and B. bulgaricsis types are important agents. This kind of cheese is commonly eaten at from three months to one year of age, depending upon the amount of flavor desired by the consumer. The following score card shows the method of judging the quality of this type of cheese: There are several groups of cheeses of dis tinct characteristics resulting from the nature of the micro-organisms which cause the ripen ing. One of these groups contains the Roque fort, Gorgonzola and Stilton in which a species of Penicillium mold plays a very important part in the ripening and development of the charac teristic flavor. In these cheeses, the mold grows all through the interior and produces a rather strong, pungent flavor. Another type is repre sented by the Camembert, originating in France, but now made also in this country. This is a soft cheese in which the ripening is brought about by the combined action of molds and bacteria. A species of Penicillum grows upon the surface, producing enzymes which work into the curd, changing it to a soft creamy, semi-fluid texture. At the same time, Oidium lactis develops on the surface and this, to gether with the lactic bacteria growing inside the cheese, is largely responsible for the final flavor. Certain other species probably play a minor part in the ripening process. Still an other group contains the Cottage, Cream, Neuf chatel and others. These are soft cheeses which undergo no special type of ripening, but depend chiefly upon the amount of cream con tained for their richness and flavor.
Ice Cream.—The manufacture and con sumption of ice creams has increased rapidly in recent years. Formerly it was considered simply as a delicacy to be used only in hot weather, but now its real food value is recognized and it is an article of year round consumption. The term °ice cream? as at present used, includes a great variety of products, the chief character istic of which is that they are eaten in a frozen condition. Most of these are made from milk or cream with the addition of sugar and some flavoring material, frequently a small amount of afiUer* being used. These products vary widely in the per cent of butter-fat and the flavoring materials used. The classification for this class of dairy products given by the Iowa Experiment Station (Iowa Bulletin 123) is: Plain ice creams, nut ice creams, fruit ice creams, bisque ice creams, parfaits, mousses, puddings, aufaits, lactos, ices, including sher bets and punches.