140 Dairy Bacteriology. 



trol the flavor of his product. Several methods have 

 been devised for this purpose and the necessary appara- 

 tus is sold by all dairy supply houses. 



The effect of the ripening of the cream is shown not 

 only in the flavor of the product, but in a number of 

 -other ways. Sour cream churns more easily, and more 

 exhaustively than does sweet cream. It is supposed that 

 the fat globules are surrounded by a film of albuminous 

 material which prevents their coalescing readily. Dur- 

 ing the ripening process, the action of the acid appar- 

 ently dissolves this enveloping substance, and the glob- 

 ules cohere more easily in the churning process. 



When, raw cream is used the ripened-cream butter 

 keeps better than that made from sweet cream. In 

 sweet cream there are few lactic bacteria, the majority 

 of the bacteria present being of various kinds, many of 

 which may be injurious, so far as the keeping quality is 

 concerned. In sour-cream butter the lactic bacteria 

 make up over 99 per cent of the bacteria present, and 

 their presence tends to prevent the development of un- 

 desirable non-acid forms. 



Source of butter flavor. The flavor of ripened-cream 

 butter has been shown to be directly connected with the 

 acid-fermentation of the cream. The amount of lactic 

 acid formed from the sugar fermented is dependent 

 upon the kind of bacteria present. The acid-producing 

 organisms that are desirable from the standpoint of the 

 butter maker form comparatively small amounts of 

 other by-products, but these undoubtedly affect the 

 flavor of the butter. As fats have the power of absorb- 

 ing odors, the butter fat absorbs some of the by-products 

 of the acid fermentation, thus acquiring a certain aroma 

 and flavor. 



