RELATION OF MICROORGANISMS TO SOME SPECIAL DAIRY PRODUCTS. 365 



the removal of the moisture. At the end of this time the milk is reduced 

 to one-fourth its original volume.* The result of this process is a pas- 

 teurized milk, with a marked reduction of the original germ content. 

 Investigations by Conn failed to show the presence of B. coli in milk 

 prepared by this process. The reduction in the bacterial content of the 

 milk is similar to that secured by other methods of pasteurization. No 

 additional sugar is added to this milk so the product is, therefore, a pas- 

 teurized milk containing a small amount of moisture. Because of the 

 small amount of moisture and the concentration of the milk sugar, the 

 bacteria which survive the heating process do not grow rapidly at low 

 temperatures. The following figures will serve to illustrate the effect of 

 this process upon the bacterial content of milk: 



Number of bacteria per c.c. in original 

 milk 



Number of bacteria per c.c. in finished 

 product 



1,250,000 

 3,000,000 

 518,000 

 894,000 

 796,000 

 150,000 



15,000 

 21,000 

 26,000 



9,950 



10,000 



5,000 



The rate at which the bacteria develop in this milk is shown by the 

 following counts: 



Number of sample 



Number of bacteria per c.c. 



The lack of moisture and concentration of milk sugar prevents the 

 rapid growth of these organisms so that bacterial changes do not take 



* Data furnished by H. W. Conn. 



