TREATMENT OF MILK FOR MARKET 153 



teurization in destroying the tuberculosis bacillus will depend 

 upon the temperature and the length of the process. It is quite 

 certain, however, that pasteurization as it is now frequently 

 adopted in our cities, which means only a momentary heating 

 of .the milk at a temperature of about 160, is not sufficient to 

 destroy the tuberculosis bacillus. 



The effect of pasteurization upon the bacteria that are prob- 

 ably associated with diarrheal diseases is as yet unknown, in- 

 asmuch as we do not know what they are. If, as it is believed, 

 these troubles are due to the very great growth of some com- 

 mon bacteria, the use of pasteurization will be efficient in re- 

 moving part of the danger of such troubles by destroying most 

 of the germs. Practical experience has also shown -that pas- 

 teurization is a useful procedure in the attempt to control the 

 diarrheal troubles'during hot weather. 



It is a matter of great importance to know whether pasteur- 

 ization of milk has any effect upon its digestibility or ease of 

 assimilation. The heat applied to it is not sufficient to produce 

 the chemical changes which occur in milk when it is boiled or 

 sterilized, or the taste which develops in boiled milk, nor do the 

 albuminoids of the milk coagulate as they do when it is boiled. 

 Laboratory experiments have seemed to show that the digestibil- 

 it) of the milk is not impaired. There has been a general feel- 

 ing in the past that while sterilization injures the digestibility 

 of the milk, pasteurization does not do so. Recently, however, 

 it has been claimed that pasteurization does impair the value 

 of the milk, though laboratory experiments do not show it. It 

 is insisted that its constant use has, in some cases, seemed to 

 result in a certain type of disease, called rickets, that has been 

 attributed to improper assimilation. The instances of this char- 

 acter are few and, as yet, somewhat uncertain. They have, 

 however, produced in recent years something of a prejudice 

 against the use of pasteurized milk. They are too rare as yet 

 to constitute any valid argument against pasteurization. 1 



i Doane and Price. Bui. 77, Md. Exper. Sta., 1901. 



