CHAPTER VII 

 PASTEURIZATION 



PASTEURIZATION is the process of heating a liquid to such 

 a temperature and for such a period of time that nearly 

 all the micro-organisms in it are killed. It also includes 

 the subsequent rapid cooling of the liquid. 



68. History. Pasteurization was developed by Louis 

 Pasteur, from whom it derives its name. In the years 

 1860 to 1864 1 this eminent scientist discovered that wine 

 fermentation is due to micro-organisms, and he found 

 that if the wine were heated to a certain temperature and 

 cooled again, the fermentation stopped. In 1886 Soxhlet 1 

 applied this method of destroying bacteria to milk and to 

 certain milk products. Pasteurization is not sterilization, 

 as shown in Chapter XVI. Nevertheless, efficient pasteur- 

 ization will kill at least 99.9 per cent of the micro- 

 organisms. 



Pasteurization was first accomplished by the " holder " 

 method. In this system all the milk or cream was heated 

 at one time in a receptacle, and held for a definite period 

 at a certain temperature, then it was cooled. Russell 2 

 was one of the first to study the application of pasteur- 

 ization to commercial dairying. He began his studies 



1 Rosenau, M. ll., Pasteurization. U. S. Hygienic Lajbora- 

 tory, Bui. 41, p. 591, 1908. 



2 Russell, H. L., Pasteurization of Milk and Cream for Direct 

 Consumption, Wis. Exp. Sta., Bui. 44, 1895. 



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