56 MILK HYGIENE 



milk without producing an alteration in appearance or 

 any of the changes above noted. 



The Bacillus foetidus lactis described by Jensen is 

 one of the colon group which has the property of pro- 

 ducing in milk an unpleasant odor similar to the odor 

 of turnips, and also a corresponding sweetish, bitter, re- 

 pulsive taste. This organism, and closely related forms, 

 are probably the real causes of the so-called turnip taste 

 of milk. Various micrococci and bacilli are capable of 

 producing a very strong bitter taste without altering the 

 milk in other respects. This change is sometimes due to 

 the production of peptone and, no doubt, to the 

 elaboration of other compounds. 



Jensen has described a small bacterium that pro- 

 duces in milk an exceedingly strong burnt taste and 

 odor, that resembles the odor and taste of malt. This 

 was so strong as to cause a malty odor throughout an 

 infected creamery. It may be that this bacterium is the 

 real cause of the so-called " malty taste " of milk and 

 butter. Another organism — a micrococcus — ^was found 

 to give milk an unpleasant fatty, burnt taste. 



A bacillus studied by Veigman and Zorn produces an 

 unpleasant soapy taste, while a bacterium mentioned 

 by Storch gives rise to an oily taste in coagulated milk. 

 Other bacteria cause other less clearly marked tastes 

 and odors that cannot be more definitely characterized 

 than as unclean. 



h. Bacteria may cause abnormal coloration of milk; 

 the most important abnormalities of this class are : 



Blue milk is caused by the Pseudomonas syncyanea, 

 (Bacillus cyanogenus), which produces a grayish color 

 on the surface of milk, while in sour milk distinct blue 

 spots appear, that may become confluent. 



Red milk. Certain bacteria, as the Bacillus prodigio- 

 sus and the Sarcina rosacea, grow on the surface of milk. 



