240 MARKET DAIRYING 
is the result of the development of the lactic fermentation. 
If other fermentations aid in the production of this im- 
portant quality of butter, they must be looked upon as 
secondary. In practice the degree or intensity of flavor 
is easily controlled by governing the formation of lactic 
acid. That is, the flavor develops gradually with the 
increase in the acidity of the cream. Sweet cream butter 
for example is almost entirely devoid of flavor, while 
cream with an average richness possesses the maximum 
amount of good flavor possible when the acidity has 
reached .6%. 
Exhaustive experiments conducted by the author (See 
Rept. Wis. Exp. Sta., 1905) show that the desirable butter 
flavor develops in the milk serum (skimmilk) and is 
absorbed from this by the butterfat. Such absorption may 
take place either during the ordinary course of cream 
ripening, or during the process of churning as would be 
the case when well ripened skimmilk (starter) is added 
to sweet cream and the mixture churned immediately. 
This explains why in creamery practice such good results 
have been obtained by churning sweet cream immediately 
after the addition of a large amount of well ripened 
starter. ; . 
Churnability. Practical experience shows that sour 
cream is more easily churnable than sweet cream. This 
is explained by the fact that the development of acid in 
cream tends to diminish its viscosity. The concussion pro- 
duced in churning causes the little microscopic fat glob- 
ules to flow together and coalesce, ultimately forming the 
small granules of butter visible in the churn. A high 
viscosity impedes the movement of these globules. It is 
