98 Dairy Bacteriology. 



ragweed, lupines, or other plants containing bitter sub- 

 stances, the milk is likely to have a bitter taste, which 

 will be noticeable at the time the milk is drawn. The 

 milk of cows at certain advanced stages of lactation may 

 show a bitter taste, due to a change in the ash constitu- 

 ents of the milk in which the lime salts are largely re- 

 placed by salts of sodium. 



There are many bacteria that will impart to milk a 

 bitter taste. Milk that has undergone the sweet-curdling 

 fermentation is likely to be bitter, as is the case with 

 pasteurized milk. Some of the acid-forming bacteria are 

 able to develop a bitter principle, the milk retaining a 

 pleasant odor and having the normal amount of acid, 

 while the taste is intensely bitter. One of the authors 

 (H) found in the case of a Wisconsin brick cheese fac- 

 tory, that the usual acid organism was almost wholly re- 

 placed by a bitter type. 



Storage of milk at very low temperatures is. conducive 

 to the appearance of a bitter taste in milk, the explana- 

 tion in this case being that the acid-forming bacteria are 

 unable- to grow at a low temperature, while some of 

 the putrefactive forms can multiply and develop these 

 astringent or bitter by-products. 



Miscellaneous fermentations of milk. There are a 

 number of other abnormal fermentations in milk that 

 occur so rarely as to be of but little economic importance. 

 Some, as the colored milks, are however, quite striking, 

 and on this account have had much attention directed to 

 them in the past. There are bacteria that are able to 

 produce various colored substances, such as red, yellow, 

 and blue. In case milk becomes seeded with large num- 

 bers of any of these kinds, it is very likely to be colored 



