158 Dairy Bacteriology. 



bleaches in color and develops a lardy flavor. 1 In addition 

 to these, cases have been found in which the defect has been 

 traced to the action of bacteria. Storch * has described a 

 lactic-acid form in a sample of tallowy butter that was able 

 to produce this disagreeable odor. 



Oily butter. Jensen has isolated one of the causes of the 

 dreaded oily butter that is reported quite frequently in 

 Denmark. The specific organism that he found belongs 

 to the sour-milk bacteria. In twenty-four hours it curdle 8 

 milk, the curd being solid like that of ordinary sour milk. 

 There is produced, however, in addition to this, an unpleas- 

 ant odor and taste resembling that of machine oil, a pe- 

 culiarity that is transmitted directly to butter made from 

 affected cream. 



Bitter butter. Now and then butter develops a bitter 

 taste that may be due to a variety of different bacterial 

 forms. In most cases, the bitter flavor in the butter is 

 derived primarily from the bacteria present in the cream 

 or milk. Several of the fermentations of this character 

 in milk are also to be found in butter. In addition to 

 these defects produced by a biological cause, bitter flavors 

 in butter are sometimes produced by the milk being im- 

 pregnated with volatile, bitter substances derived from 

 weeds. 



Moldy butter. This defect is perhaps the most serious 

 because most common. It is produced by the development 

 of a number of different varieties of molds. The trouble 

 appears most frequently in packed butter on the outside of 

 the mass of butter in contact with the tub. Mold spores 

 are so widely disseminated that if proper conditions are 



1 Fischer, Hyg. Bund, 5:573. 



2 Storch, 18 Kept. Danish Agric. Expt, Stat., 1890. 



