6 



The American Public Health Association 



of babies milk is a special problem of 

 city milk supply, and this should be 

 remembered in relation to pasteuriza- 

 tion. Pasteurization protects babies 

 from diarrheal diseases, typhoid fever, 

 diphtheria, scarlet fever, and from bo- 

 vine tuberculosis and if, in the opinion 

 of some physicians, this advantage is 

 outweighed by other considerations, or 

 at least in some cases makes the use 

 of raw milk advisable, it does not fol- 

 low that for these reasons older chil- 

 dren and adults should surrender the 

 protection from communicable diseases 

 that the use of pasteurized milk af- 

 fords." 



IV. The Process of jMilk Pasteuri- 

 zation. 



The Committee questions whether 

 this is the place to undertake the pres- 

 entation of the origin and development 

 of the heating proceses which have re- 

 sulted in the adoption of the modern 

 systems of the practical pasteuriza- 

 tion of milk. It does not consider it 

 necesary to refer extensively to the 

 entire series of laboratory studies re- 

 sulting in the expression of opinions 

 on the destructive action of heating 

 upon cultures of pathogenic bacteria 

 or their thermal death-points. 



(1) Holding System Required. The 

 Committee feels that it has been suffi- 

 ciently demonstrated that the so-called 

 "holding" system of pasteurization of 

 milk intended for prompt consumption 

 in the fresh state is so much superior 

 to any other type of method as to war- 

 rant the limiting of its activities to 

 that general system. There are prac- 

 tically two stages or operations in 

 every form of application of the "hold- 

 ing" system, i. e., the heating and the 

 holding. This applies whether the 

 milk is heated in one apparatus and 

 held in another, or is heated and held 

 in the same tank, coil, or bottle. 



The process of pasteurizing milk 

 consists of four essential parts: (a) 



the temperature to which the milk 

 must be raised, (b) the length of the 

 time period for which the milk must 

 be held above the minimum tempera- 

 ture, (c) the time in which the milk 

 must be cooled after the boiling pe- 

 riod, and (d) the temperature to which 

 the milk must be cooled. 



To the temperature and time re- 

 quired must be added either tempera- 

 ture or time, or both, as a factor of 

 safety against irregular functioning of 

 the apparatus used to pasteurize the 

 milk. Some types of apparatus re- 

 quire a far greater factor of safety than 

 others. Regardless of the means em- 

 ployed to apply the pasteurizing treat- 

 ment to the milk, each and every drop 

 of milk must be raised to or above the 

 minimum temperature. The holding 

 tim.e must be as long or longer than 

 the minimum time fixed for the hold- 

 ing period. No averaging of temper- 

 ature or of the holding time can be 

 permitted — that is, if some of the milk 

 is heated to a higher temperature, the 

 remainder must not be ,heated to a 

 lower temperature, or if some of the 

 milk is held beyond the holding time 

 the remainder rnust not be held for a 

 shorter time. 



(2) Pasteurization Process Defined. 

 As the pasteurization of milk is a pub- 

 lic health measure, that determination 

 of time and temperature which insures 

 the greatest protection from any possi- 

 ble pathogenic infection is the standard / 

 to be fixed for milk for public con- 

 sumption. The Committee believes 

 that the process of pasteurizing milk 

 for human consumption should consist 

 of subjecting the milk to a temperature 

 not lower than 145 degrees F. for not 

 less than 30 minutes. It feels that the 

 scientific evidence already presented 

 from studies on the process of pas- 

 teurization justifies the requirements 

 above stated for pasteurized milk, and 

 that by fixing only a minimum temper- 

 ature and time, sufficient latitude is 



