BUTTERMAKING 241 
evident, therefore, that anything that reduces the viscosity 
of cream, will facilitate the churning. 
As a rule, too, the greater the churnability of cream 
the smaller the loss of fat in the buttermilk. 
Frothing. Experience shows that ripened cream is 
less subject to frothing or foaming than unripened. This 
is probably due to the reduced viscosity of ripened cream 
and the consequent greater churnability of same. 
Temperature. Sour cream can be churned at higher 
temperatures than sweet cream with less loss of fat in 
the buttermilk. This is of great practical importance 
since it would be difficult, if not impossible, for most 
creameries to get low enough temperatures for the suc- 
cessful churning of sweet cream. Indeed, many cream- 
eries fail to get a low enough churning temperature for 
ripened cream. 
Keeping Quality. It has been found that butter with 
the best keeping quality is obtained from well ripened 
cream. It is true, however, that butter made from cream 
that has been ripened a little too far will posesss very 
poor keeping quality. An acidity of .5% should be placed 
as the limit when good keeping quality is desired. 
METHODS OF CREAM RIPENING. 
There are three ways in which cream is ripened at the 
present time: 
1. By the unaided development of the lactic fermenta- 
tion called natural ripening. 
2. By first destroying the bulk of the bacteria in cream 
by heat and then inoculating same with cultures of 
lactic acid bacteria. This method is known as pasteurized 
cream ripening. 
