BACTERIA IX BUTTER -MAKING. 23 I 



CONTROL OF CREAM-RIPENING. 



The butter-maker has no control over the kinds of bacteria 

 which find their way into his cream. In a creamery, he must 

 take what the different farmers furnish him in their cream. If 

 the cream chances to have a majority of species which can 

 produce good results his butter will turn out well, but, if the 

 cream chances to have more species unfavorable to the develop- 

 ment of proper flavors, his butter falls off in quality and no 

 care he may take in the butter-making can raise the flavor. 

 It is evident from these facts that if there could be devised a 

 means by which the butter-maker could be assured of his cream 

 having the proper species of bacteria, it would result in a much 

 greater uniformity in the product. That such a method is 

 possible seems to be suggested by the success with which a 

 similar device has been adopted by brewers in regulating their 

 fermentation. In past years the fermentation of malt was liable 

 to similar variations, due to irregularities in the microorgan- 

 isms (yeasts) which produced it. The introduction of the 

 microscope and pure cultures of yeast have revolutionized 

 brewing. Bacteriologists have thought that the same may be 

 possible and feasible in butter-making. 



About ten years ago it was suggested that an artificial means 

 of controlling this process might be devised. Professor Storch 

 of Copenhagen first conceived that it might be possible to fur- 

 nish butter-makers with cultures of the proper species of bac- 

 teria to add to their cream for the purpose of ripening, some- 

 what as yeast is used in brewing. This experimenter was one 

 of the first of dairy bacteriologists, and not only conceived the 

 method but put it into practical operation in Denmark. His 

 method consisted, (i) in treating the cream by the process of 

 pasteurization, at about 165 F., for the purpose of destroying 

 most of the bacteria that might be present, and (2) in adding 

 to it a properly prepared culture of bacteria, whose value in 



