17. METHOD OF TESTING BUTTER SUBSTITUTES.--Very often oleomargarine and process butter bear such a close resemblance to genuine butter that it is almost impossible to detect the difference. However, there is a simple test by which these substitutes can always be distinguished from butter, and this should be applied whenever there is any doubt about the matter. To make this test, place the fat in a tablespoon or a small dish and heat it directly over the flame until it boils, stirring it occasionally to assist in the melting. If it is oleomargarine or process butter, it will sputter noisily and take on a curdled appearance; whereas, if it is butter, it will melt and even boil without sputtering although it foams to a certain extent.
CHEESE
CHARACTERISTICS AND CARE OF CHEESE
18. ORIGIN, PRODUCTION, AND USE OF CHEESE.--Cheese is a product that is manufactured from the solids of milk, and it provides a valuable food. The making of cheese was known in ancient times, it having probably originated through a desire to utilize an oversupply of milk. When cheese was first made, the fact that bacteria were present was not known, nor were the reasons for the spoiling of milk understood; but it was learned that milk can be kept if most of its water is removed. This discovery was very important, for it led to various methods of making cheese and proved that cheese making was a satisfactory and convenient means of storing nourishment in a form that was not bulky and that would keep for long periods of time. From a very small beginning, the different methods of making cheese became popular, until at the present time more than three hundred varieties are made and their manufacture forms one of the large industries of the world.
In the United States, nearly all the cheese used up to about 50 years ago was made on farms, and to a great extent by housewives, but about that time a factory for the making of this product was started in the state of New York, and it proved a profitable enterprise. From this beginning, the business of making cheese commercially in this country has grown until now cheese is almost entirely a factory-made product, in the manufacture of which the states of New York and Wisconsin lead.
19. In either the commercial or the home production of cheese, skim milk with all or part of the cream removed is used for some varieties, while whole milk is used for others, the composition depending largely on the kind of milk that is employed. Rennet is added to the milk to coagulate it, and then the curd, from which nearly all the water is removed, is allowed to ripen. To produce characteristic odors, flavors, and consistency, various coloring and flavoring materials, as well as bacteria, are added to the curd. The action of these bacteria is really the chief factor in the making of cheese and they are therefore not only desirable but necessary. Non-desirable bacteria, however, result in the formation of bad odors, flavors, and gases in the finished product and these must be carefully guarded against by cheese makers.
20. Cheese offers a valuable source of nutriment for the body, because its food value ranks high. As is shown in Fig. 3, the food value in 1 pound of cheese is equivalent to that in 2 pounds of beef, that in 24 eggs, or that in 4 pounds of fish. The use of cheese, however, is not nearly so great as its food value warrants, the amount used in the United States per capita being only about 3-1/2 pounds annually. This is a condition that should be overcome, for there is a large variety of ways in which cheese can be used to advantage in the diet. When eaten raw, it is very appetizing, and when used with soups, sauces, and foods that have a bland taste, it lends additional flavor and makes an especially attractive dish. In addition, the fact that it is an economical food and can be conveniently kept and stored should recommend its frequent use.