that the number of organisms may vary widely in
unripened cream, but that the germ content of the ripened product is
more uniform. When cream is ready for the churn, it often contains
500,000,000 organisms per cc., and frequently even a higher number. This
represents a germ content that has no parallel in any natural material.

The larger proportion of bacteria in cream as it is found in the
creamery belong to the acid-producing class, but in the process of
ripening, these forms seem to thrive still better, so that when it is
ready for churning the germ content of the cream is practically made up
of this type.

~Effect on churning.~ In fresh cream the fat globules which are suspended
in the milk serum are surrounded by a film of albuminous material which
prevents them from coalescing readily. During the ripening changes, this
enveloping substance is modified, probably by partial solution, so that
the globules cohere when agitated, as in churning. The result is that
ripened cream churns more easily, and as it is possible to cause a
larger number of the smaller fat-globules to cohere to the butter
granules, the yield is slightly larger--a point of considerable
economic importance where large quantities of butter are made.

~Development of acid.~ The result of this enormous bacterial
multiplication is that acid is produced in cream, lactic being the
principal acid so formed.

Other organic acids are undoubtedly formed as well as certain aromatic
products. While the production of acid as a result of fermentative
activity is usually accompanied with a development of flavor, the flavor
is not directly produced by the formation of acid. If cream is treated
in proper proportions with a commercial acid, as hydrochloric,[154] it
assumes the same churning properties as found in normally ripened cream,
but is devoid of the desired aromatic qualities. Lactic acid[155] has
also been used in a similar way but with no better results.

The amount of acidity that should be developed under natural conditions
so as to secure the optimum quality as to flavor and aroma is the most
important question in cream ripening. Concerning this there have been
two somewhat divergent views as to what is best in practice, some
holding that better results were obtained with cream ripened to a high
degree of acidity than where a less amount was developed.[156] The
present tendency seems to be to develop somewhat more than formerly, as
it is thought th