196 Effect of Heat. 



Burri, Russell and Hastings). These germs decompose proteids 

 and carbohydrates by forming butyric acid with gas production, 

 and peptonizing the proteids. Boiled milk decomposes more read- 

 ily than raw milk from the bacteria which contaminate it after the 

 heating process. 



Relative to the effects of pasteurization, the following should 

 be noted : As a result of the effect of 85 deg. C. the bacterial num- 

 ber dropped from 10,000,000 to 500 per c. c. These remaining 

 organisms however, which consist principally of peptonizing var- 

 ieties, multiply rapidly to very great numbers if the milk is brought 

 again to 25 degrees C., frequently producing changes in taste, 

 which becomes bitter and irritating, but sometimes without mark- 

 edly changing either the appearance or taste. 



This however does not render pasteurization hazardous, since 

 it is possible through proper handling of the milk to prevent these 

 undesirable processes. The marketing of pasteurized milk becomes 

 dangerous only when the consumer considers that pasteurized 

 milk being free of germs may be kept indefinitely under almost 

 any circumstances and therefore takes less care of pasteurized 

 milk than he would of the raw product; besides this consumers 

 repeatedly heat such milk and thereby diminish its nutritive value 

 more and more. It is for this reason that various authorities 

 have taken action against the indiscriminate distribution of pas- 

 teurized milk. It should be required that the date of pasteuriza- 

 tion be indicated on each bottle. 



A statement from the officials of the city of Leipsic asserts that pasteurized milk is 

 not more valuable than raw milk, but that it appears to be of lesser value on account 

 of the destruction of its raw condition and the consequent changes. Any manipulation 

 of milk which claims to extend its keeping properties by several hours, and which 

 possibly may be used in the establishment of false valuation by statements that the 

 milk has a lasting, keeping quality and a freedom from bacteria, is directly dangerous 

 and injurious to health if the consumer is not thoroughly informed with regard to the 

 effectiveness and limitations of pasteurization. The action of peptonizing bacteria in 

 milk that has been pasteurized is pointed out, and recommendation is made against the 

 purchase of milk which was pasteurized more than three days previously. The official 

 statement al?o calls attention to Barlow's disease, and to the dangers attending improper 

 keeping of such milk. 



Sometimes pasteurized milk which is never free of bacteria is 

 marketed under the attractive declaration of "free from disease- 

 bacteria." What is the relation of pasteurization to such a claim 

 as this? According to the experiments of Forster, van Geuns, de 

 Mann, Ringeling and Koning, de Jong, de Graaf, and Beck, the 

 disease-producing bacteria are affected differently by high tem- 

 peratures while in milk than when in bouillon or water. Thus 

 for instance heating for a half hour at 70 deg. C. is not always 

 sufficient to destroy colon bacteria. Tubercle bacilli are still more 

 resistant. According to Kolle and Beck they are not destroyed 

 with certainty even when subjected to heating for a half hour at 

 80 deg. C., especially not when they are isolated from the influence 



