286 Report of Farmers' Ia^stitutes 



THE PASTEURIZATION OF DAIRY BY-PRODUCTS IN NEW YORK STATE 



W. D. DOTTERRER 



Bacteriologist, New York State Commission for the Investigation of Bovine 



Tuberculosis 



The work summarized here is the result of an investigation 

 undertaken under the direction of the Bacteriological Department 

 of the New York Agricultural Experiment Station on the 

 methods, efficiency and effects of pasteurizing dairy by-products. 

 In the course of the investigation visits were made to seven 

 American cheddar factories and one skimming station where pas- 

 teurization was being carried out. According to the 1915 report 

 of the New York State Department of Agi-iculture there are 

 about 950 cheese factories in the state. Of these, forty-eight are 

 definitely known to be pasteurizing the whey. Twenty-four of 

 the latter make American cheddar, thirteen make Swiss, nine 

 make limburg and two make brick cheese. At only one of the 

 factories visited were the temperatures used in pasteurization high 

 enough to meet the lowest temperature (178°) usually required 

 in those states which have laws on the subject, and at this factors- 

 such temperatures were reached only occasionally. The Penn- 

 sylvania law requires 178° F., Iowa 185, Minnesota 180 and 

 Michigan 185, with the option of 145 for thirty minutes. All of 

 the factories except two, however, were using temperatures high 

 enough to meet the requirements of the option allowed by the 

 Michigan law. These two factories were also losing a great part 

 of the value of pasteurization by adding separator slop and water 

 after the whey was too cool to kill bacteria. One other factory 

 followed this same practice so that pasteurization, which otherwise 

 would have been effective, was rendered unsatisfactory. 



The temperatures necessary to kill disease germs have been 

 studied by a number of men. The work has been summarized by 

 Rosenau,* who verifies the conclusions by work of his own. As 

 low a temperature as 140° F. for 20 minutes has been found to 



* Rosenau, M. J. The Thermal Death Point of Pathogenic Microorganisms 

 in ]\Iilk. U. S. Public Health and Marine Hospital Service, Hygienic Labora- 

 tory Bui. 42, 1908. 



