THE PASTEURIZATION OF MILK 



between the inner and outer shell, there are placed 

 near the top two perforated pipes, into which hot 

 water is forced. The water is thrown through 

 the perforations, in jets, against the outer surface 

 of the inner shell. It flows down, following the 

 contour of the tank, and drops from the bot- 

 tom, from whence it is again pumped through 

 the pipes after being reheated. The milk in the 

 meantime is kept in agitation by means of the 

 paddles. 



In any of these tanks it usually requires from 

 fifteen minutes to twenty-five minutes to raise the 

 milk from 50 to a temperature of 145. The 

 proper temperature having been attained, the steam 

 is shut off, and the milk is allowed to remain hot 

 in the tank for any desired length of time. 



The tank form of pasteurizer in practice shows 

 excellent results. In plants where there are large 

 quantities of milk to be pasteurized it is necessary 

 that two, three or more tanks be arranged in se- 

 ries. This insures a continuous flow of milk 

 through the cooling apparatus and the filling de- 

 vices. In actual operation with three tanks, it 

 occurs that while one tank is being emptied after 

 heating and holding, the milk is being held in the 



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