PASTEURIZATION 193 



cities is more than six or eight hours old, the question has 

 only an academic interest. 



Personally, I cannot see why pasteurized milk needs 

 greater care than raw milk. Both require careful handling 

 and neglect is just as serious in the one case as in the other* 



How long will pasteurized milk keep? 



The keeping qualities of pasteurized milk have been 

 much discussed, and laws have even been proposed forbid- 

 ding the sale of pasteurized milk after it is forty-eight hours 

 old. Thus the sanitary code of the city of New York states 

 that "pasteurized milk must be delivered to the consumer 

 within twenty-four hours of the pasteurization." The 

 number of bacteria allowed in a pasteurized milk has not 

 yet been made the subject of law. As a general rule there 

 is a reduction of about ninety to ninety-nine per cent of 

 the bacteria contained in the raw milk, provided the raw 

 milk is not excessively dirty and provided the pasteuriza- 

 tion is effectively done. The surviving bacteria continue 

 to grow and multiply until they reach into the millions per 

 cubic centimetre. The question now being considered by 

 health officers and milk experts is how many bacteria 

 should be permitted in pasteurized milk offered for sale. 

 To be on the safe side it may be said that pasteurized milk 

 should not contain over 50,000 bacteria per cubic centi- 

 metre. 



This question has long been considered a very serious 

 one, for the reason that it is commonly believed that pas- 

 teurized milk does not sour normally, but putrefies with 

 the production of poisonous toxins. Fortunately this is 

 not the case with milk pasteurized at the temperatures 

 now recommended. In other words, pasteurized milk spoils 

 just as raw milk spoils. 



It is not generally known that pasteurized milk sours 

 normally. The fable that pasteurized milk turns putrid 

 was imported from Germany, where sterilization was at- 



