172 DAIRY FARMING 



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 is difficult to get low enough temperatures for the 

 successful churning of sweet 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 possess very 

 poor keeping quality. An acidity of .5% should be placed 

 as the limit when good keeping quality is desired. 



CONTROL OF THE RIPENING PROCESS. 



We have learned that the highly desirable flavor and 

 aroma of butter are produced by the development of the 

 lactic fermentation. In the following discussion we shall 

 take up the means of controlling this fermentation and 

 treat of the more mechanical side of cream ripening. This 

 will include: (i) the ripening temperature; (2) time 

 in ripening; (3) agitation of cream during ripening. 



Ripening Temperature. Since the lactic acid bac- 

 teria develop best at a temperature of 90 to 98 F. 

 it would seem desirable to ripen cream at these tem- 

 peratures. But this is not practicable because of the 

 unfavorable effect of high temperatures on the body 

 of the cream and the butter. Good butter can be pro- 

 duced, however, under a wide range of ripening tem- 

 peratures. The limits may be placed at 60 and 80. 

 Temperatures below 60 are too unfavorable for the 

 development of the lactic acid bacteria. Any check 

 upon the growth of these germs increases the chances 

 for the development of other kinds of bacteria. But 

 it may be added that when cream has reached an 



