MARKET MILK 



173 



for thirty minutes, but as applied under commercial conditions 

 it is the process of heating for a short or long period, as the 

 different methods demand, at temperatures usually between 

 140° and 185° F. The process is followed by rapid cooling. 



Pasteurization, when first practiced by milk-dealers in this 

 country, was carried on secretly, and, except as a means of 

 preserving the milk, was regarded by them as a process of no 

 value. As the practice became more general, the subject of 

 pasteurization was studied, and its value as a means of destroy- 

 ing disease-producing bacteria was recognized. In conse- 

 quence of the recognition of the merits of the process there has 

 been during the last ten years a rapid increase in the quantity 

 of milk pasteurized, particularly in the larger cities. 



The general tendency in this country to-day is toward the 

 pasteurization of all market milk, with the exception of cer- 

 tified and inspected milk from tuberculin-tested herds. Some 

 idea of the extent of pasteurization may be gained from the 

 following table. The figures 1 were supplied by the milk-in- 

 vestigations section of the Dairy Division and were obtained 

 from replies to circular letters sent to health officers. 



Extent of Pasteurization of Milk in Cities in the United States 



Population of Cities 



Number of 

 Cities An- 

 swering 

 Question 



More than 



50 Per 

 Cent Pas- 

 teurized 



11 to 50 

 Per Cent 



Pas- 

 teurized 



to 10 Per 

 Cent Pas- 

 teurized 



None Pas- 

 teurized 



More than 500,000 . 

 100,001 to 500,000 . 

 75,001 to 100,000 . 

 50,001 to 75,000 . . 

 25,001 to 50,000 . . 

 10,001 to 25,000 . . 



9 

 40 

 19 

 30 



78 

 168 



7 



12 



5 



4 



13 



10 



2 

 20 



8 

 15 

 31 

 40 



Lis 







6 



4 



6 

 12 

 18 







2 



2 



5 



22 



100 



Total . . . . 



344 



51 



116 



46 



131 



1 These figures were obtained through the kindness of Mr. Ernest 

 Kelly and Mr. L. B. Cook. 



