Bacteria in Butter- Making . 129 



product is dependent upon the character and the extent 

 of the ripening changes. A careful study of large num- 

 bers of dairy bacteria as has been done by Conn, shows 

 that these problems can be separated, if pure cultures 

 are used. 



127. Development of acid. In the ripening of cream 

 acid is almost invariably developed. This development 

 is essential, as it renders churning easier, and increases 

 the yield of butter. The acid formed is largely lactic, 

 and is produced by a decomposition of the milk-sugar. 

 So characteristic of cream-ripening is this production of 

 acid that the process is frequently spoken of as souring, 

 although it must be kept in mind that the process in- 

 volves much more than mere acid production. Normal 

 butter made from ripened cream always has a character- 

 istic flavor, which quality is distinct from the acid for- 

 mation. This difference is seen in the results obtained 

 by Tiemann 1 when cream is ripened by the addition of 

 hydrochloric acid. When so treated, cream can be easily 

 churned, but the product is lacking in the aromatic qual- 

 ities found in normally ripened cream. 



128. Flavor. The flavor of butter is that quality that 

 is judged by the sense of taste. Good, bad, or indiffer- 

 ent flavors may be produced in butter as a result of bac- 

 terial action. In fact, the production of flavor in ripened 

 cream butter is in large part due to the fermentative pro- 

 ducts of microbes, although it is to some extent modified 

 by the inherent qualities of the milk that are induced by 

 the character of the feed which is consumed by the 

 animal. 



129. Aroma. The aroma of butter is often confounded 

 with that of flavor, but this quality is dependent upon 



1 Tiemann, Milch Ztg., 23: 701. 

 9-B. 



