EXPERIMENT STATION BULLETINS. 531 



KEEPING QUALITIES OF BUTTER. 



IV. CKEAM RIPENING AND ITS INFLUENCE. (CONTRIBUTION). 



BACTERIA IN CREAM, THEIR NUMBERS AND TYPES AND THEIR ITINERARY IN 



THE MANUFACTURE OF BUTTER. 



CHAS. W. BROWN AND KURT PEISER. 



INTRODUCTION. 



Modern students of butter constantly are paying more attention to the 

 methods of handling and to tlie condition of the raw products, the milk 

 and the cream prior to its receipt at the creamery, as influencing 

 markedly or even predetermining the quality and life of the butter. 

 Cream produced under the usual conditions frequently contains a large 

 number of bacteria which comprise a number of species from various 

 sources. Many of these species find conditions favorable for growth and 

 as a result multiply more or less rapidh'. By far the larger number of 

 the bacteria in milk are admitted from external sources and it is due to 

 the presence and growth of these that milk is caused to change in taste 

 and odor and to undergo the processes of souring and decomposition. A 

 large number of each of the different types present in the milk is carried 

 over with the cream during separation. Many of these types cause the 

 same changes in cream as in milk, some discriminate and others are in- 

 different. The difficulties and problems involved in the handling of 

 cream for the manufacture of butter are so numerous and complex that 

 a uniformity in the finished product is not easily attained. Creamerj^- 

 men realize that butter of the best quality cannot be made from cream 

 that is produced under unsanitary and neglectful conditions. The de- 

 struction of the natural, sweet, rich flavor of cream through the care- 

 lessness of the producer and through the neglect of the cream is mani- 

 fest in the butter. 



PURPOSE. 



This paper deals with the bacteria in cream relative to the numerical 

 count and prevailing types and traces these types through the different 

 steps in the manufacture of butter. 



