belongs. The problem of the modern butter maker is to control the
kinds of bacteria growing in the cream.

The temperature at which cream is held during the ripening process
is favorable to the growth of the acid-forming bacteria; hence, in
ripe cream, they are practically the only kind of bacteria to be
found. It must be remembered however, that there are different
classes of acid-forming organisms, some of which produce desirable
flavors, while others are distinctly harmful.

The intensity of flavor of butter is, in a general way, directly
related to the amount of acid that is formed in the cream. A low
acidity at time of churning is usually associated with a mild
flavor, while a higher degree of acidity, up to a certain point,
imparts a more pronounced flavor to the product. If cream is
over-ripened, the quality of the flavor is seriously impaired.

In determining the acidity of cream, a definite volume is taken, and
the acidity determined by titration, expressing the results as such
a per cent of lactic acid. Manifestly, the amount of fat in the
cream influences the apparent per cent of acidity. The acidity will
not usually exceed 0.5 to 0.7 per cent, but in reality the serum
will contain more than this, as the acid is formed in the serum, the
butter fat having no role whatever. In a very rich cream, 40 to 50
per cent fat, it is impossible to develop more than 0.4 to 0.5 per
cent of acidity, and the flavor of the butter will be low, because
of the relation between the amount of acid and fat, while in a thin
cream having the same acidity, the ratio between the amounts of fat
and acid will be very different. For example, in one hundred pounds
of 50 per cent cream of 0.5 per cent acidity there will be one-half
pound of acid and fifty pounds of fat; in the same quantity of cream
containing 20 per cent of fat and having an acidity of 0.5 per cent
there will be one-half pound of acid to twenty pounds of fat. The
flavor of the butter from the rich cream will be quite different in
intensity from that made from the thinner cream.

The acidity of cream cannot be determined with any degree of
accuracy by the taste or odor. Every butter maker should have some
method of determining the degree of acidity in his cream, so that he
may better control the flavor of his product. Several methods have
been devised for this purpose and the necessary apparatus is sold by
all dairy supply houses.

The effect of the ripening of the c