THE MILK SITUATION IN THE DISTRICT OF COLUMBIA. 93 



HELD AND CONTINUOUS PASTEURIZATION. 



The temperatures and durations of exposure above indicated refer 

 to what is known as " held " pasteurization, or the " holder " process, 

 a specific quantity of milk being retained integrally in what is 

 known as the holder, or pasteurizing receptacle, during the pre- 

 scribed period of time. The " flash " method, or " continuous " pas- 

 teurization denotes where the milk is constantly flowing in and out 

 of the pasteurizer, being subjected during the brief interval of 

 exposure to more intense heat, though not sufficient to destroy the 

 ferments of the milk. It is urged against the latter process that the 

 milk in different parts of the receptacle is not subjected uniformly to 

 the heat, and that for this reason the pathogenic germs are not as 

 certainly killed as by the holder process. 



OBJECTIONS TO COMMERCIAL PASTEURIZATION. 



Much adverse comment has been expressed against commercial 

 pasteurization on account of the imperfect and inefficient manner 

 in which, according to actual experience, milk has been pasteurized 

 for the general market; This criticism has been manifestly just in 

 many instances, and has been due in large measure to the introduc- 

 tion of " continuous," or " flash," pasteurization. This method of 

 so-called pasteurization is fairly characterized as a makeshift or sub- 

 terfuge resorted to by dairymen, often innocently and unintention- 

 ally, on the recommendation of representatives of certain machinery 

 interests promoting pasteurizing apparatus of this character. The 

 investigations of the committee have impelled it firmly to the belief 

 that this latter method of alleged pasteurization is not only mechan- 

 ically impracticable, owing to the impossibility of subjecting the 

 milk uniformly to the specificed amount of heat, but results, in op- 

 eration, either in failing to destroy the pathogenic germs by too 

 mild an application of heat to certain portions of the volume of 

 milk, or in making the heating of all or particular portions of the 

 milk in the container so intense as to devitalize it and encourage its 

 rapid putrefaction. 



" Held " pasteurization, as has been explained, is the generally 

 commended method of retaining the fluid in the tank or receptacle 

 for a given period of time, instead of permitting a continuous flow in 

 or out of the chamber. In the " continuous," or " flash," process the 

 milk is customarily exposed only momentarily to the heat at a tem- 

 perature of from 73 to 74 C. (which is equivalent to from 163.4 

 to 165.2 F.). It will be observed that this degree of temperature 

 is considerably in excess of that recommended for pasteurization under 

 the " held " process, namely, 140 to 145 F. 



In an article entitled " The Pasteurized Milk Fraud," x by Arno 

 Dosch, reference is made to the contest which is now being waged in 

 Chicago in favor of a purer milk supply and to the fraud which is 

 being practiced upon the public in certain communities by placing on 

 sale milk which, though represented to be pasteurized, has not been 

 treated according to approved methods of pasteurization, the " flash " 

 process being largely resorted to in this connection. In the article 



* Pearson's Magazine, December, 1910, p. 721. 



