2 20 ILLINOIS STATE DAIRYMEN'S ASSOCIATION. 



bacteria action and not from tlie action of unorganized ferments. It must 

 be stated, however, that although this general explanation is beyond dis- 

 pute there are some problems connected with cream ripening that we do 

 flot yet fully understand, and which we must hope in the future to solve 

 more satisfactorily. 



EFFECT OF DIFFERENT SPECIES OF BACTERIA UPON CREAM 



RIPENING. 



We have learned, further, as the result of the work of many bacter- 

 iologists, that the so-called dairy bacteria are of many kinds. By this 

 4s meant that the bacteria which may get into the milk in considerable 

 numbers under ordinary or slightly unusual circumstances are of many 

 different species, just as many di^erent species of weeds will grow up- 

 on a piece of land left to itself. The source of these bacteria has been 

 studied and is now more or less understood. They come largely from the 

 exterior of the cow, especially from dirt clinging to her hair, or from 

 the milk ducts; or they may be in the vessel into which the milk is 

 ^rawn. There are other sources, but these are the chief. Now these 

 various species of bacterid have very different effects upon the cream if 

 they are present during the ripening process. The majority of the 

 species appear to have no especial influence, and may grow in the cream 



■jv^ithout any especial effect upon the butter. Some of them, however, pro- 

 fluce changes in the cream which give rise to the products imparting the 

 desired flavor and aroma. Others produce changes which give rise to an 

 abnormal ripening resulting in an improper consistency in the cream 

 and more especially in unpleasant flavors and aromas. These of course 

 the buttermaker desires to keep out of his cream, for it is these, in large 

 degree at least, which produce the inferior qualities of butter which come 



Tom improper cream ripening. Accordingly to our present knowledge 

 ^he majority of the species of dairy bacteria may be looked upon as neu- 

 tral so far as concerns an effect upon butter flavor. A few may be looked 

 upon as favorable and a few as unfavorable. 



