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CITY MILK SUPPLY 



TABLE 85. EFFECT OF DIFFERENT METHODS OF COOLING ON THE BACTERIAL CON- 

 TENT OF PASTEURIZED MILK (AYRES AND JOHNSON) 



The table shows no increased bacterial growth in samples 1 and 2 

 from holding the pasteurized milk 5 hr. after bottling hot, even though 

 the temperature ranged between 80 and 100F. which limits comprise the 

 temperatures most favorable for bacterial development. In sample 3 the 

 milk that was cooled slowly does show an increased growth over that which 

 was cooled rapidly, but even so it is to be remembered that the experiments 

 represent extreme conditions in slow cooling and so it would seem proper 

 to infer from the three samples that the cooling process can be delayed 

 but that it should not extend over 5 hr. The writers make application 

 of this in their process of cooling with an air blast, milk bottled hot. 

 They strongly emphasize the fact that the table shows that milk not cooled 

 to low temperatures soon has a higher bacterial count than either milk 

 cooled slowly or that cooled rapidly, which should drive home the practical 

 point that milk must be cooled to low temperatures after pasteurization. 



Inspection of Pasteurizing Plants. The inspection of pasteurizing 

 plants by those in official position should be done in a systematic and 

 thorough manner. The description by Sturgis of the way it is done by 

 the Department of Health of New York City gives a clear idea of how 

 such work should be conducted. 



"The complete inspection of a pasteurizing plant involves the examination 

 before, during and after the operation, in order to note the condition of the ap- 

 paratus and the care given to its cleanliness at all times, as well as to watch the 



