550 



MANUAL OF MILK PRODUCTS 



TABLE SHOWING THE GERMICIDAL ACTION IN Cow's MILK 



the time the milk begins to sour, approximately 90 per cent 

 of the total germ-content will consist of this type, and by the 

 time the milk curdles, this group will usually contain 97 to 99 

 per cent of the entire germ-content. 



The germ-content of milk at a given age will depend pri- 

 marily on its original contamination and on the temperature 

 at which it is held. Other things being equal, the lower the 

 initial contamination, the smaller will be the resulting germ- 

 content at any future time in the history of the milk. Since 

 the rate at which bacteria can grow is largely dependent on 

 temperature, the germ-content resulting from a given initial 

 contamination will depend primarily on this factor. If milk 

 is held at a temperature of 50 or below, bacteria grow quite 

 slowly, but the rate of growth increases very rapidly as the 

 temperatures rise above this point. The marked influence of 

 temperature on the rate of growth of bacteria in milk is well 

 illustrated by the following figures. These figures were 

 obtained by dividing a given lot of milk and holding at the 



1 Fahrenheit. 



