184 BACTERIA IN BUTTER. 



If the butter-makers of this country should place upon the 

 market a milder and milder flavored butter there is little ques- 

 tion that the public taste would adapt itself to the new con- 

 ditions and the demand would in time be for a milder flavor. 

 What is Cream Ripening? The chief agency in cream 

 ripening is the growth of bacteria. The bacteria of milk col- 

 lect in the cream and multiply very rapidly at the tempera- 

 ture at which the cream is kept during the ripening. The 

 growth of the bacteria may be best illustrated by two ex- 

 amples of ripening cream, both representing the process in 

 winter weather when the number at the outset was small and 

 the ripening slow. 



The numbers here given are somewhat larger than those 

 found in the ordinary ripened cream. A large series of tests 

 has shown that in a normally ripened cream the number of 

 bacteria present will vary from 100,000,000 to 1,500,000,000 

 per c.c., about 500,000,000 being an average number. 



This enormous growth of bacteria, occurring within a day 

 or two days, will produce profound changes in the chemical 

 nature of the cream. The bacteria, having multiplied to 

 this great extent, must not only have consumed a cer- 

 tain quantity of material for food, but must also have pro- 

 duced a series of by-products, either as excretions or as 

 decomposition products, and the chemical nature of the cream 

 will consequently be very much changed. 



That this bacteria growth is the chief cause of the changes 

 in ripening cream is beyond question. Whether it is the only 

 cause of the changes has not yet been demonstrated. We have 

 already learned that there is present in milk, even when freshly 

 drawn, at least one of the so-called chemical ferments or 



