Bacteria and Butter- Making. 157 



Jensen found the trouble to be due to several different 

 putrefactive bacteria. One form which he called Bacillus 

 fcetidus lactis, a close ally of the common feces bacillus, 

 produced this rotten odor and taste in milk in a very short 

 time. Fortunately, this organism was easily killed by a 

 comparatively low heat, so that pasteurization of the cream 

 and use of a culture starter quickly eliminated the trouble, 

 where it was tried. 



Turnip-flavored butter. Butter sometimes acquires a 

 peculiar flavor recalling the order of turnips, rutabagas, 

 and other root crops. Often this trouble is due to feed- 

 ing, there being in several of these crops, aromatic sub- 

 stances that pass directly into the milk, but in some in- 

 stances the trouble arises from bacteria that are able to 

 produce decomposition products, 1 the odor and taste of 

 which strongly recalls these vegetables. 



"Cowy" butter. Frequently there is to be noted in 

 milk a peculiar odor that resmbles that of the cow stable. 

 Usually this defect in milk has been ascribed to the absorp- 

 tion of impure gases by the milk as it cools, although the 

 gases and odors naturally present in fresh mills: have this 

 peculiar property that is demonstrable by certain methods 

 of aeration. Occasionally it is transmitted to butter, and 

 recently Pammel" has isolated from butter a bacillus that 

 produced in milk the same peculiar odor so commonly pres- 

 ent in stables. 



Lardy and tallowy butter. The presence of this un- 

 pleasant taste in butter may be due to a variety of causes. 

 In some instances, improper food seems to be the source of 

 the trouble; then again,. butter exposed to direct sunlight 



Jensen, Milch Zeit., 1892, 6, Nos. 5 and 6. 



Bull. 21, Iowa Expt. Stat., p. 803. 



