Fermentations in Milk. 73 



mals. At certain stages in lactation, a bitter salty taste is 

 occasionally to be noted that is peculiar to individual ani- 

 mals. 



A considerable number of cases of bitter milk have, how- 

 ever, been traced to bacterial origin. For a number of 

 years the bitter fermentation of milk was thought to be 

 associated with the butyric fermentation, but Weigmann 1 

 showed that the two conditions were not dependent upon 

 each other. He found that the organism which produced 

 the bitter taste acted upon the casein. 



Conn 2 observed a coccus form in bitter cream that was 

 able to impart a bitter flavor to milk. Sometimes a bitter 

 condition does not develop in the milk, but may appear 

 later in the milk products, as in the case of a micrococcus 

 which Freudenreich 3 found in cheese. 



Cream ripened at low temperatures not infrequently de- 

 velops a bitter flavor, showing that the optimum tempera- 

 ture for this type of fermentation is below the typical 

 lactic acid change. 



It has long been a question how to account chemically 

 for the bitter taste in milk. Various ideas have been ad- 

 vanced, but Freudenreich has demonstrated in one case 

 that a bitter substance is formed in the milk that can be 

 isolated by adding alcohol. 



Milk that has been cooked is likely to develop a bitter 

 condition. The explanation of this is that the bacteria 

 producing the bitter substances usually possess endospores, 

 and that while the boiling or sterilizing of milk easily 

 kills the lactic acid germs, these forms on account of their 

 greater resisting powers are not destroyed by the heat. 



i Weigmann. Milch Zeit., 1890, p. 881. 



8 Conn, 3 Kept. Storrs Expt. Stat., 1890, p. 153. 



a Freudenreich, Fiihl. Landw. Ztg., 43: 361. 



