92 THE MILK SITUATION IN THE DISTRICT OP COLUMBIA. 



ness may be destroyed without injuriously affecting the beneficial 

 components of the milk. 



While authorities are not agreed as to the most advantageous 

 degree of heat and the period for which this should be applied to 

 effect perfect pasteurization, there is a substantial disposition among 

 those consulted by the committee in favor of a range of from 140 

 to 145 F. for an exposure of 20 to 30 minutes (which period shall be 

 interpreted to exclude the time required to attain the prescribed 

 temperature, referring solely to the interval during which the stated 

 temperature is actually maintained uniformly throughout the body 

 of milk under treatment). From the evidence at hand we may 

 therefore safely conclude that the heating of milk to 140 F. for 30 

 minutes or 145 F. 20 minutes destroys the pathogenic microorgan- 

 isms without injuriously affecting the composition or quality of the 

 milk and without sensibly impairing its food value, the milk retaining 

 the taste of fresh milk and remaining quite as digestible. 



EFFECT OF PASTEURIZATION ON GERM LIFE. 



As to the effect of pasteurization upon the germ life in milk, Dr. 

 Melvin, Chief of the Bureau of Animal Industry, , observes that, if 

 done at temperatures recommended by the bureau (namely, 140 or 

 145 F. for 30 or 20 minutes, respectively), while destroying most, 

 if not all, of the pathogenic bacteria, the process will not eliminate 

 all of the lactic acid bacteria, the advantage of destroying injurious 

 germs greatly outweighing any possible loss from the destruction of 

 germs that might be considered harmless. 



Surg. Gen. Wyman, of the Public Health and Marine-Hospital 

 Service, confirms the statement that pasteurization, if performed at 

 a temperature of 145 F. for 20 minutes, destroys pathogenic bac- 

 teria, but does not destroy the ferments of the milk, which latter are 

 understood to play an important role in its digestion and assimila- 

 tion. On the contrary, Dr. Crichton, commissioner of health of 

 Seattle, W asn -? asserts that pasteurization destroys the beneficial 

 germs, as it does largely the prejudicial, but that the latter come to 

 the front and multiply with such rapidity that, after a certain length 

 of time, the milk becomes absolutely dangerous. Pasteurization is 

 probably a wise makeshift, he persists, but never to take the place of 

 good, clean, natural milk. Dr. Clemmer, health officer of Columbus, 

 Ohio, contends that friendly germs are more easily destroyed than 

 prejudicial ones. But this view is contradicted by the testimony of 

 most authorities consulted by the committee. 



Dr. Hamill is disinclined to admit that milk contains any germs 

 of a beneficial character, but acknowledges that pasteurization if 

 properly carried out will destroy all so-called pathogenic that is 

 to say, disease-breeding organisms. 



According to Dr. Coit, the enforcement of the tuberculin test will, 

 as elsewhere stated in this report, diminish human infection only 

 to the extent that tuberculosis is now disseminated by market milk; 

 having the effect, in his judgment, of reducing to the extent of about 

 25 per cent, the number of cases of tuberculosis occurring in children. 

 Human infection from bovine sources would, in his view, be en- 

 tirely obviated, however, by efficient pasteurization. 



