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The American Public Health Association 



Summary. 



Information collected throughout the 

 United States and the Dominion of 

 Canada shows that there are approx- 

 imately 4,200 pasteurization plants in 

 operation in these countries at the 

 present time and that only' a very 

 limited number of these installations 

 are controlled from a public health 

 point of view. There is little uniform- 

 ity in the definitions of milk pasteur- 

 ization used by Federal, state and mun- 

 icipal branches of government which 

 leads to much confusion as to the 

 proper meaning of "pasteurized milk". 

 There is also a very apparent lack of 

 understanding on the part of the pub- 

 lic regarding the actual meaning of 

 pasteurization and the reason for its 

 general application. 



The results of scientific workers on 

 the effect of pasteurization on the com- 

 position of milk indicate that there is 

 little, if any, change in the chemical 

 composition so far as can be determined 

 by chemical analysis. A large amount 

 of experimental work has been con- 

 ducted on the undesirable effects 

 caused by pasteurization on milk that 

 is to be used for infant feeding. Some 

 conflicting opinions have resulted from 

 this work but it is now generally re- 

 cognized that any ill effects from the 

 use of such milk for infant feeding 

 can be easily remedied by the addition 

 of certain common substances such as 

 orange juice and potato water. The 

 protection that pasteurization affords 

 older children and adults from com- 

 municable diseases far overshadow any 

 of the easily remedied ill effects as- 

 sociated with infant feeding. 



The evidence presented on the var- 

 ious methods used for the pasteurization 

 of milk indicate that the "holding" sys- 

 tem is so much superior to any other 

 as to justify its universal application 

 for the pasteurization of milk to be 

 used for human consumption. The 



process of pasteurization of milk should 

 consist in subjecting the milk to a tem- 

 perature not lower than 145 degrees 

 F. for not less than 30 minutes. 



The mechanical features of pasteur- 

 ization plants has not been given suffi- 

 cient attention by many of the depart- 

 ments supervising the pasteurization 

 of milk, and defects in pasteurizing ap- 

 paratus are found in many plants now 

 in operation. Defects may be found 

 associated with nearly every part 

 of pasteurization apparatus which 

 can be eliminated by proper de- 

 sign, construction and operation of 

 the plant. It is possible to construct 

 a commercial pasteurization plant on 

 a practical basis without inherently 

 dangerous defects. Such a' plant when 

 properly operated should produce a 

 pasteurized milk which is safe for 

 human consumption. 



The analytical control of pasteuriza- 

 tion plants is a subject that has been 

 given considerable attention by health 

 authorities and many methods have 

 been studied for determining the ef- 

 ficiency of pasteurization plants and 

 the various apparatus associated with 

 the pasteurization of milk. The meth- 

 ods discussed in this report include the 

 physical, chemical, physico-chemical 

 and biological. The physical methods 

 involving the testing of sensitive in- 

 struments used to control the process, 

 and biological tests to study the ef- 

 ficiency of plants and the quality of 

 their effluents appear to be the best 

 of those already devised and applied 

 on a practical basis. It is clearly evi- 

 dent that the analytical control of pas- 

 teurization plants calls for the active 

 co-operation of engineers and labora- 

 tory investigators before satisfactory 

 interpretations can be made and effic- 

 ient results accomplished. 



State and municipal supervision of 

 pasteurization should involve certain 

 fundamentals for the protection of the 

 public health. It appears to be gener- 



