15G Dairy Bacteriology. 



later undergo a change that renders them worthless for table 

 use. This change is usually a rancidity that is observed 

 in all stale products of this class. The cause of this rancid 

 condition in butter has been attributed to the action of 

 living organisms, particularly those that form butyric acid, 

 to the influence of light, air, etc. Undoubtedly under cer- 

 tain conditions, rancidity may be produced by the opera- 

 tion of all of the above agents. Although the subject has 

 been quite extensively studied, there is yet considerable 

 variation in opinion as to the exact nature of the causal 

 agents. 1 



BACTERIAL DEFECTS IN" BUTTER. 



Lack of flavor. Often this may be due to improper 

 handling of the cream in not allowing it to ripen far 

 enough, but sometimes it is impossible to produce a high 

 flavor. The lack of flavor in this case is due to the ab- 

 sence of the proper flavor-producing organisms. This con- 

 dition can usually be overcome by the addition of a proper 

 starter. The relation between flavor and desirable bacteria 

 is very intimate, and troubles of this kind usually arise 

 because the proper forms commonly found in the cream 

 have been supplanted by other species that do not possess 

 the ability of forming these aromatic substances so neces- 

 sary in sour-cream butter. 



Putrid butter. This specific butter trouble has been ob- 

 served in Denmark, where it has been studied by Jensen. 8 

 Butter affected by it rapidly acquires a peculiar putrid 

 odor that ruins it for table use. Sometimes, this flavor 

 may be developed in the cream previous to churning. 



iReinmann. Cent. f. Bakt., 1900, 6:131; Jensen, Landw. Jahr. d. Schweiz, 1901. 

 Jensen, Cent. f. Bakt., 1891, 11:409. 



