34 AGRICULTURE OF MAINE. 



Milk, having been produced carefully, and which is clean, 

 must be kept where it is clean and, hence, must be immediately 

 removed from the stable to the milk house. Milk easily takes 

 up foreign odors that may be about the stable, such as turnips, 

 ensilage, etc. 



The only possible way to put clean milk on the market is to 

 produce it cleanly. When bacteria once get into the milk it is 

 impossible to get them out. It is the multiplication of bacteria 

 and their toxin production that controls the souring or rotting 

 of milk. The stable atmosphere contains, perhaps, millions of 

 bacteria to the cubic centimeter, and when the milk is left in 

 the barn in an open receptacle for any length of time it be- 

 comes contaminated to a very great degree. 



When milk is produced in as clean a manner as possible it 

 contains a certain kind of bacteria. Even if milk could be 

 drawn from the cow into a sterile receptacle without being 

 contaminated, it would contain bacteria. These bacteria are 

 always present in milk, even before it is produced. They are 

 lactic acid bacteria and they are the agents that cause the 

 natural souring of milk. 



It is important to exclude bacteria foreign to milk because, 

 if they multiply rapidly and overpower the natural bacteria of 

 milk, they cause the rotting of milk instead of the natural 

 souring. This natural souring is, of course, very important in 

 the manufacture of butter. 



Milk, as soon as it is drawn from the cow, becomes dead 

 matter and at once begins to deteriorate. This deterioration 

 is caused by the natural action of lactic acid bacteria. The 

 control of this deterioration, or the action of other bacteria, 

 is through low temperature naturally, and through pasteuriza- 

 tion which is rather an unnatural method. 



Warm milk is a perfect media for bacteria to grow in, con- 

 sequently it is important to cool milk to a low temperature 

 while the bacterial content is yet low. The cooling should be 

 accomplished immediately after the milk is strained, by running 

 it over a cooler filled with ice or else by setting the cans in ice 

 water. Milk should be cooled to at least 50° F. and 40° F. 

 is better, if possible. 



