54 PRACTICAL DAIRY BACTERIOLOGY 



Other Colors in Milk. Several other bacteria are capable of 

 producing color in milk. Some turn it yellow, some green, 

 some brown and some black. By choosing proper species of 

 bacteria, fermentations can be produced in milk, showing all 

 the colors of the rainbow. But these phenomena, although 

 found in the laboratory, and of great scientific interest, do not 

 appear in practical dairying. Some of these colors occasionally 

 appear on soft cheeses that are ripening, but they do not occur 

 in milk. For these reasons we shall not here consider them 

 further. 



MILK HAVING THE TASTE OF TURNIPS 



Milk is sometimes found to develop a turnipy taste, a fact 

 which, until recently, has been attributed to cows eating turnips, 

 or some similarly tasting food. In some cases this is probably 

 the correct explanation ; but a careful study of the phenomenon 

 has recently shown that some of their troubles are due to the 

 growth of bacteria in the milk. If the taste is directly due 

 to the food eaten by the cows, it will appear in the milk when 

 the milk is drawn. But in some cases this turnipy taste does 

 not occur until several hours after the milk has been drawn: 

 consequently it must be due to the growth of micro-organisms. 1 

 Bacteria producing this turnipy taste have been separated from 

 milk and, by experiment, have been shown to produce this 

 turnipy taste (B. lactis fcetidus). The dairyman, therefore, must 

 remember that this trouble may be due to the food, or there 

 may b a bacteria infection. He can easily determine which it 

 : is by 'noticing whether the taste is present when the milk is 

 drawn, or develops some hours afterward. In the latter case 

 he may get rid of it by enforcing greater cleanliness, even 

 though he still feeds turnips to his cows. 



1 Gruber. Hyg. Rund., p. 626, 1903. 

 Ritland. Zeit. f. Fleisch. u. Milch. Hyg., xiv., p. 276, 1904. 



