THE CHEMISTRY OF BUTTER MAKING 65 



churned, or its churnability, is influenced by a num- 

 ber of factors, as season of the year, food consumed, 

 period of lactation, and individuality of the animals 

 producing the milk. When cows have not been salted 

 regularly, the milk is not normal in composition, 

 and difficulties in churning frequently arise. The 

 character of the food consumed influences the com- 

 position of the butter fats, which in turn affects the 

 churnability of the cream. The effect of the food 

 upon the character and composition of the milk will 

 be discussed in another chapter of this work. When 

 cows are advanced in their period of lactation, the 

 globules are smaller in size, the milk is more viscous 

 in character, and has a different composition from 

 milk in the first stages of lactation. This affects 

 the completeness and rapidity with which cream 

 yields to the churning process. In churning abnor- 

 mal creams, the conditions must be carefully studied 

 and the cause of any difficulty determined ; then the 

 temperature of churning, degree of ripeness, or 

 other conditions may be changed so as to meet the 

 requirements of the cream in question. Occasion- 

 ally abnormal conditions of the cream affecting 

 churning are due to some form of fermentation 

 resulting in the production of gas or rendering the 

 milk proteids more viscous in character, which in 

 turn affects the churnability of the cream. 



The process of churning should be stopped when 

 the butter globules are granular and about the size 

 of wlieat kernels. If the cream has been properly 



