d is placed in cold water at
once, the bacterial content of the cream will be low, and it will be
less likely to contain undesirable forms than the cream which is
obtained from the shallow pans.

In separator cream the bacteria will be represented by the kinds
present in the milk at time of separation. If this milk is quite
old, the cream will contain large numbers of bacteria; if, however,
early separation is made and the milk is clean, the bacterial
content of the cream will be low.

=Types of butter.= Butter may be divided into two types--acid or
sour-cream, and sweet-cream, depending upon whether the cream is
allowed to undergo the acid fermentation or not before it is
churned. In southern Europe, it is the custom to churn the cream as
sweet as possible, and the resulting product possesses only the
natural, or primary milk flavor. To one accustomed to butter made
from sour or ripened cream, this taste is flat, and if the butter is
free from salt, may remind one of grease. Sweet-cream butter has a
delicate flavor when it is made from good milk, and the taste for it
is rapidly acquired. In some centers, as in Paris, the market
demands this type of butter quite exclusively.

If the cream is allowed to undergo the acid fermentation before
churning, the butter has a much higher degree of flavor and one that
differs materially in kind. Under primitive methods, it was
difficult to keep the cream sweet until it could be churned. On the
small farm with gravity creaming in shallow vessels and infrequent
churning, the cream was certain to be sour when churned.
Undoubtedly, the making of butter from sour cream came into use
because of its greater convenience; people became accustomed to
sour-cream butter, and at the present time it is used in the greater
part of the world, and is the type made in all of the great dairy
countries.

=Ripening of cream.= In modern dairy practice the souring of the cream
is called the _ripening_ process, and is, where the best methods are
employed, largely under the control of the butter maker. The changes
that go on in the ripening process are the same as have been
discussed in the acid fermentation of milk. The increase in acid is
accompanied by an enormous increase in the number of bacteria; the
ripe cream will contain hundreds of millions of bacteria in each
cubic centimeter. The effect of this germ life is to improve or
injure the butter, depending upon the class of bacteria to which it