402 MANUAL OF MILK PRODUCTS 



stir thoroughly. Continue this process for two or three days. 

 Care must be exercised in controlling the temperature so that 

 the cream will not be over-ripened. On the second and third 

 days, perhaps, the ripening temperature will have to be dropped 

 to 60° or 65° F. 



Another method would be to add a small amount of butter- 

 milk to the first batch of cream, which would serve as a starter. 

 The reason why this method should be used in case a bitter 

 flavor develops is that the bitter flavor is produced by bacteria 

 which grow in milk and cream at temperatures of 50° F. or 

 below; the bacteria will not grow even at these favorable 

 temperatures if the cream is sour. 



The ripening of cream 



" By the ripening of cream is meant the changes it undergoes 

 from the time of separation until it is added to the churn. On 

 these changes depends very largely the quality of butter as 

 regards texture and flavor. The temperature at which cream 

 is held determines the firmness or texture, while the flavor is 

 dependent on the by-products from the bacterial growth. 



" The purpose of ripening cream is fundamentally that of 

 giving the butter the desired flavor and aroma, but in addition 

 it increases the ease and efficiency of churning. Cream is 

 ripened in one of two ways : 



" First, it sours or ripens as a result of the action of bacteria 

 which are normally present in milk and cream ; or, 



"Second, it ripens as a result of action of certain kinds of 

 bacteria which are added in what is termed a ' starter.' ' 

 (Keithley. 1 ) 



Many times the use of a starter in ripening the cream will be 

 found advantageous. The preparation of the starter is given 

 by Guthrie 2 and Fisk as follows : 



1 Farmers' Bulletin No. 541. 2 C. U. Cir. 13. 



