CHAPTER XIII. 



PASTEURIZATION. 



Definition. The word pasteurization has its derivation from 

 Pasteur, a French scientist. Pasteurization consists in heat- 

 ing milk somewhere between 140 F. and 212 F. This kills 

 practically all germs in a vegetative state. Since most of them 

 are in a vegetative condition, the process kills almost all the 

 organisms. The heating is followed by rapid cooling. " Sterili- 

 zation" is a word which is some times used incorrectly in con- 

 nection with pasteurization. Sterilization means that milk or 

 any other substance has been heated so often or to such a high 

 temperature as to entirely destroy every living micro-organism 

 present. In order to get a substance thoroughly sterilized 

 without heating under pressure, it is essential that it be heated 

 about thirty minutes on each of three or more successive days. 

 Pasteurization in the dairy industry was introduced by Pro- 

 fessor Storch of the Royal Experiment Station, Copenhagen, 

 Denmark. 



Methods of Pasteurization. 



(1) Intermittent. 



(2) Continuous. 



1. Intermittent pasteurization is usually accomplished in 

 vats or cans. It is used nearly exclusively when pasteurization 

 is practiced on a small scale, such as preparation of starters 

 in creameries, pasteurizing cream and milk on the farm, etc. 

 Intermittent pasteurization is as efficient, and undoubtedly more 

 so, than the continuous method. The substance pasteurized 

 is usually exposed to the high temperature a longer time than 

 it would be by the intermittent system. In the continuous 



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