PASTEURIZATION A417 
to the theory of disinfection and since disinfection is a time process the 
continuous process allows a greater reduction of bacteria. 
Effect of Pasteurization on Bacteria. This has been given much 
study in order to refute the argument against pasteurization that 
pasteurized milk putrifies rather than sours. Ayers and Johnson (1913) 
Milk Pasteurized for 30 Minutes at 
Milk e2es°C 011°C | TPR. 82 BPC s78°C. 933°C 
(1445°F ) (160°F) (170°F) (180°F) (190°R) (200°) 
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Fre. 69.—The Hypothetical Relation of the Bacterial Groups in Raw and Pasteur- 
ized Milk. (After Ayers and Johnson.) 
studied the bacteria in pasteurized milk by means of their milk-tube 
method. They used the holder process with a temperature of 62.8° C. 
for thirty minutes in most of their experiments. Their results are 
graphically summarized in Fig. 69 from which it will be seen that pas- 
teurization increased the percentage of acid-forming bacteria in the milk. 
Higher temperatures of pasteurization caused a different relation to 
