CHAPTER XIII. 
BACTERIA IN BUTTER AND OLEOMARGARINE. 
BACTERIA IN BUTTER-MAKING. 
In the making of butter, bacteria are the dairyman's allies. The 
butter-maker always, even though unconsciously, makes direct use 
of bacteria when he subjects his cream to a process almost univer- 
sally adopted in butter-making, called ripening, or, in Europe, 
more commonly called souring. In butter-making, the cream is 
not usually churned immediately after it is separated from the milk, 
but it is allowed to lie in a moderately warm vat for a period of twelve 
to twenty-four hours or even longer, that it may ripen. In some 
places there is a demand for what is known as sweet cream butter, 
which is simply butter made from fresh cream without ripening; 
but such a demand is very limited, and most butter is made from 
ripened cream. 
CREAM-RIPENING. 
The custom of ripening cream is an old one, doubtless as old 
as the process of butter-making. Upon a farm where the amount 
of cream is small, it is always necessary to allow it to accumulate 
for some days till there is sufficient for a proper churning. During 
this period it is sure to undergo ripening without any intention on 
the part of the farmer. On ordinary farms, the cream is left to take 
care of itself, and is thus sure to be ripened by the time there is 
enough to churn. But the centralization of butter-making into 
creameries, where large quantities of cream are handled daily, has 
put a new aspect upon the problem. The ripening will no longer 
care for itself, but must be carefully attended to by the butter-maker. 
The necessity for some accurate means of controlling the ripening 
181 
