Though the chief points in the manufacture of cheese are well known, and are discussed in detail in other publications[4] of this department, it may not be out of place to review them here. Cheese is made ordinarily from whole milk, and most of the kinds best known in the United States from cows’ milk. In every 8 parts of milk by weight there is approximately 1 part of solid nutrients, the remainder being water. For our present purpose we may think of the nutrients as being equally divided into three groups—protein substances (casein and albumin principally), fat, and milk sugar. In the process of cheese making the casein, which constitutes more than three-fourths of the proteids of the milk, is precipitated by rennet, forming a curd. Most of the fat attaches itself to this curd. The curd is broken up, and the whole is heated to a temperature between 96° and 108° F. The whey is drained off and carries with it most of the milk sugar and the albumin. The curd is salted and pressed. It is kept for several weeks or longer in a cool place, where it “ripens,” developing flavors through the action of bacteria or other microorganisms, and also undergoing certain other marked changes. The average cheese while fresh and moist contains proteids and fat in much the same ratio as that in which they are found in the milk. More than one-fourth its weight is proteid, about one-third fats, and one-third water. There are always present small amounts of albumin and sugar which have clung to the curd. Owing to the addition of salt, the percentage of mineral matter is high compared with that of most other foods. In ripening, cheese changes in texture and its original pastiness gives away to a somewhat granular consistency in some types, or to a waxy or a buttery consistency in others. The above brief outline refers only to the essentials of cheese making. In practice, there are many variations with respect to the kind of milk used, the proportion of butter fat or cream retained in or added to the milk, with respect to the methods followed in separating, preparing, seasoning, and handling the curd, and to the handling and ripening of the cheese. It follows that there is an almost endless number of cheeses with different names and of different appearance and flavor. Cheese making was formerly a home or farm industry, but is now, in the United States at least, very largely a commercial enterprise carried on in factories. It differs from many industries in that the factories are almost always located in the country or in the smaller towns rather than in large cities, this being more true of cheese making than of the manufacture of potted cheeses or other special articles, which has become a large industry. It is worthy of mention in this connection that the making of cheese crackers and other bakers’ goods in which cheese is an ingredient has developed into an important part of the baking trade. FOOTNOTES: