ream is shown not only in the
flavor of the product, but in a number of other ways. Sour cream
churns more easily, and more exhaustively than does sweet cream. It
is supposed that the fat globules are surrounded by a film of
albuminous material which prevents their coalescing readily. During
the ripening process, the action of the acid apparently dissolves
this enveloping substance, and the globules cohere more easily in
the churning process.

When raw cream is used the ripened-cream butter keeps better than
that made from sweet cream. In sweet cream there are few lactic
bacteria, the majority of the bacteria present being of various
kinds, many of which may be injurious, so far as the keeping quality
is concerned. In sour-cream butter the lactic bacteria make up over
99 per cent of the bacteria present, and their presence tends to
prevent the development of undesirable non-acid forms.

=Source of butter flavor.= The flavor of ripened-cream butter has been
shown to be directly connected with the acid-fermentation of the
cream. The amount of lactic acid formed from the sugar fermented is
dependent upon the kind of bacteria present. The acid-producing
organisms that are desirable from the standpoint of the butter maker
form comparatively small amounts of other by-products, but these
undoubtedly affect the flavor of the butter. As fats have the power
of absorbing odors, the butter fat absorbs some of the by-products
of the acid fermentation, thus acquiring a certain aroma and
flavor.

It is not necessary that the cream be ripened, in order to have the
fat acquire a flavor, for if sweet cream is churned with a
considerable proportion of sour milk, the butter will have much the
same flavor, both as to intensity and kind, as though the cream had
been allowed to sour naturally. A process of butter making known as
the LeClair method is based on this principle. The flavor-producing
substances can also be absorbed by the butter after it is churned,
by working the butter in contact with sour milk. Attempts have been
made to add pure lactic acid to the cream, instead of allowing the
acid to be formed by the bacteria, but while the physical effect on
the cream is the same, the flavor and aroma of the butter are
deficient, because the acid itself does not supply the necessary
aromatic products. This emphasizes the importance of the by-products
of the acid fermentation other than the lactic-acid.

In the past numerous attempts h