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