PASTEURIZATION. 



187 



Results oH Continuous Pasteurization of Milk at 

 160—165° P. (71—74 c.) 



TABLE XVI. 



Tncnty Tests, Percentage of Bacteria Killed, 99.95. 



238. The growth of bacteria in mUk. 



The increase of the bacteria in milk depends most- 

 ly upon the temperature at which it is kept during 

 the first few hours after it is drawn. According to 

 Grotenfelt's "Modern Dairy Practice" we find that 

 Cropf and Eiserich in Munich found 60,000 to 100,- 

 000 bacteria per cubic centimeter in milk shortly 

 after it had been drawn. This sample was kept in a 

 cellar at a temperature of 12.5 degrees C. (56.5 de- 

 grees P.). After two" hours the bacterial content was 

 four times a,s great as at first; after three hours it 

 was eight times as great; after five hours it was 

 twenty-six times as great, and after six hours it was 

 1,803 times at great. Another portion of this milk 

 was held at 35 degrees C. (95° P.) in an incubator 

 and the bacteria originally present multiplied twen- 

 ty-three times in two hours ; 215 times in four hours ; 

 803 times in five hours and 3,800 times in six hours. 

 The development of the bacteria in the milk kept in 

 ice during the same period of time was so slight as 



