CHAPTER VII. 



BACTERIA IN BUTTER. 



THE relation of bacteria to butter, the second great dairy 

 product, divides itself into two heads : ( i ) The influence 

 of bacteria upon cream in the preparation for butter-mak- 

 ing by the process of cream ripening; (2) the relation 

 of bacteria to butter itself, and the changes which they pro- 

 duce therein. More is known in regard to the former sub- 

 ject than the latter, and the question of cream ripening will 

 be first considered. 



CREAM RIPENING. 



Butter is made from cream which has been separated from 

 the milk either by gravity or by the centrifugal method. The 

 shaking which it receives in churning causes the fat to adhere 

 together in little masses which are finally bulky enough to be 

 removed from the liquid in which they float. In most pro- 

 cesses of butter-making the cream is, however, not churned 

 immediately after it is separated from the milk, but is allowed 

 to undergo a process of ripening. It is true there is a certain 

 demand for sweet cream butter, but the demand has hitherto 

 been a very slight one, and even at the present time there 

 is very little market for this product. Whether the future 

 taste of the butter consumers will change so as to increase the 

 demand for sweet cream butter cannot be predicted, but at 

 the present time butter is made almost universally from 

 cream that has been allowed to undergo the process of 

 ripening. 



The origin of the process of cream ripening was probably 

 purely accidental. Until within comparatively few years but- 

 ter has been made only upon individual farms and in most 



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