Since microorganisms differ in thermal resistance, the data for a single organism should not serve as a basis for establishing minimum pasteurization standards at all temperatures. Were data for all microorganisms that limit pasteurization available for plotting “safe” minimum-process graphs, the resulting curve would not be a straight line. Until additional thermal resistance data are available, approved “no-hold” and similar high temperature processes should require more severe treatments than those predicted from the limited criteria that have commonly been used to indicate safe treatment at temperatures in the range of vat and HTST pasteurization.

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Author notes

1Presented at the Annual Dairy Industry Conference at the University of California, Davis, January 23, 1956