TREATMENT OF CREAM PREVIOUS TO THE CHURNING. 221 



what was wanted; the beer might turn bitter, be "off 

 flavor," etc., although the raw products used were of the 

 very best quality. Until lately we were placed in the same 

 difficulty in the fermentation industry called the manu- 

 facture of sour-cream butter. The composition of the 

 starter used is not known, and it perhaps contains a large 

 number of injurious bacteria. Although the quality of 

 the cream was excellent, a bitter, oily, turnipy or other 

 kinds of diseased butter may have been obtained owing to 

 the introduction of injurious bacteria into the cream from 

 the starter. The effort has perhaps been made to produce 

 good milk, to handle it properly throughout, to take good 

 care of it during the transportation to the creamery, to 

 care for it there according to all the rules of the art, to cool, 

 separate and pasteurize it a relatively germ-free cream 

 being thus obtained; and after all this the delicate product 

 is calmly mixed with a fluid the qualities of which are 

 only partially known, and all preceding efforts may thus 

 be overthrown. By a good deal of practice and experi- 

 ence the ripening may certainly be successfully conducted 

 in this way. A Danish butter-maker has thus, as I recently 

 learned, been using the same kind of starter for fourteen 

 years without having ever had a faulty ripening. In the 

 same way experienced brewers were able to make good 

 beer also before the introduction of pure cultures; but 

 there could be no certainty of a good, uniform, and well- 

 keeping product until the adoption of the latter process. 



Butter-makers cannot prepare such a starter them- 

 selves, however, but are obliged to turn to a bacteriological 

 laboratory that can furnish them with pure cultures of 

 lactic-acid bacteria. We shall return to the pure cultures 

 of these bacteria at the end of this chapter in connection 



