RULES AND REASONS FOR FARM CARE OF MILK. 



105 



and thus injuring the product for direct consumption, is undesirable for 

 dairy products. The viscosity of such milk is increased so much that 

 it cannot be thoroughly creamed for butter making, and the fermentation 

 changes that go in the curd also injure it in some cases for cheese making. 

 The slimy fermentations are more apt to occur during summer weather, 

 but epidemics of this kind have been reported under winter conditions. 

 Defective milks of this type are quite frequent, as 

 several epidemics come to our notice almost every 

 year. A careful bacteriological study of apparently 

 normal milk often reveals the presence of slime- 

 forming bacteria i limited numbers that are kept 

 under subjection by some more dominant ferment 

 change such as the sour milk fermentation. 



BITTER FERMENTATIONS. 



A bitter condition in milk may be induced by a 

 variety of causes, but true fermentations that pro- 

 duce bitter products are the result mainly of bacterial 

 action. This type of fermentation is caused by 

 widely different bacteria. The writer has isolated a 

 pure acid organism, one that soured milk without 

 the production of any gaseous product, and yet 

 milk impregnated with this organism developed a 

 taste as bitter as gall. Many of the digestive or pep- 

 tonizing fermentations develop bitter flavors. Where 

 butyric acid is formed in milk, a bitter taste is 

 often noted. In heated milks especially, bitter 

 flavors frequently occur. This condition arises from 

 the fact that the heating process destroys the normal 

 lactic acid bacteria and as these bitter ferment germs 

 are usually spore-bearing organisms, they are able 

 to resist the heating process. 



Bitter milk or cream is occasionally noted in 

 Some of the bacteria that are able to 



in length. form bitter substance can grow at considerably- 



lower temperatures than the ordinary sour milk forms; and so, if milk 

 is kept where it is near the freezing point, these bitter-forming species develop 

 ( more rapidly than the lactic species, thus giving the peculiar flavor to the 

 milk. In some cases the bitter flavor in milk, unless it is too pronounced, 

 disappears when the product is made up into butter or cheese. 



VARIOUS OTHER FERMENTATIONS. 



The above fermentative changes include the more important ones that 

 are liable to appear in milk as a result of bacterial infection. In addition 

 to these there are numerous other changes that occur from time to time. 



J 



FIG. 9. A "slimy" milk. 



11 g fe l e n t the winter. 



