e milk than is the
case in butter making.

Every effort should therefore be made to furnish to the cheese maker
the quality of milk from which he can prepare fine cheese. In other
words, the milk should be produced under clean conditions and
carefully cooled and handled until delivered to the maker. Poor milk
from a single farm may have such an effect upon the cheese made from
the milk of twenty farms as to depreciate the selling value of the
entire product several cents per pound.

The tests that have been previously described (p. 105) have been
devised especially for testing the quality of the milk for cheese
making purposes, and are of the greatest service to the maker in
tracing the source of poor milk.

=Cheddar cheese.= The first step in the making of cheddar cheese is
the "ripening" of the milk, or the development of a small amount of
acid. In this fermentation, the development of acid is preceded by
an enormous increase in the number of acid-forming bacteria. Milk
for cheese making should show an acidity of about 0.2 per cent or
slightly more than in fresh milk. In other words, the maker wishes
the milk to be in such condition, bacteriologically, that if kept at
a temperature favorable for the growth of the acid-forming bacteria,
the acidity will increase rapidly.

The curdling of the milk to precipitate the cheese solids is
produced by the addition of rennet, which is obtained by extracting
the fourth stomach of the young calf with a solution of common salt.
In the past the maker prepared his own rennet solution from the
dried stomachs ("rennets"), but at present, the extract is prepared
commercially, in a much more uniform manner. The rapidity of the
curdling is dependent upon the acidity of the milk. In order to
secure proper rennet action, a slight increase of acid over that
found in fresh milk is usually necessary; thus at the very beginning
of the process of making cheddar cheese, the bacteria are of
importance.

As the milk curdles, the bacteria are enclosed in the curd as are
the fat globules. The curd is cut into small fragments by means of
a curd knife, and as the mass is warmed, the acid develops, causing
the curd particles to shrink, thus expressing the whey. Within a
short time, the volume of the curd is not more than one-eighth that
of the milk, but in the curd are held over 75 per cent of the
bacteria of the milk. To secure rapid curdling in the vat, the milk
is warmed to 85 deg. to 90 deg