164 AGRICULTURE. 



and tastes after standing for some time, and 

 occasionally these are present when it is milked. 

 There are three common sources of these ob- 

 jectionable tastes and odors in milk. 



(i) Certain Foods. — When food eaten by 

 cows contains any strong volatile substance, 

 this will be carried through the circulation of 

 the cow and into the milk. For example, when 

 a cow eats onions, turnips, or even some strong 

 weeds, the characteristic odor and taste may be 

 recognized in the milk. These odors may be 

 mostly driven off by heating the milk. Ordi- 

 narily very little trouble is experienced from 

 this source, as the common feeds have no notice- 

 able effect on the flavor of the milk. 



(2) The Air. — Any odors, even if not very 

 pronounced, may be readily absorbed from the 

 air by milk or butter. Milk exposed to the air 

 of an ill-kept barn, or a musty cellar, often ab- 

 sorbs odors that make it very objectionable for 

 food. 



(3) Bacteria. — The most common cause of 

 objectionable tastes and odors of milk is the 

 action of various bacteria. Bacteria of many 

 kinds are found in milk, and various kinds of 

 fermentation result from their action. In addi- 

 tion to common souring, milk may be decom- 

 posed, giving off bad odors, may become ropy, 

 or bitter, or even have an abnormal color due 

 to the action of bacteria. 



