Thermal Inactivation of Campylobacter Species, Yersinia enterocolitica, and Hemorrhagic Escherichia coli 0157:H7 in Fluid Milk

Abstract

Heat treatment of raw milk in an HTST pasteurizer operated at 60.0 to 72.0°C for a minimum holding time of 16.2 s rapidly inactivated mixtures of hemorrhagic Escherichia coli O157:H7, Yersinia enterocolitica and Campylobacter spp. (C. fetus, C. coli, and C. jejuni). Each of the three genera in the mixture was inoculated at a level of approximately 1.0 × 105 cfu/ml. At 60.0°C, hemorrhagic E. coli showed a maximum 2 log10 reduction in counts and no viability at ≥64.5°C. Yersinia enterocolitica and Campylobacter spp. showed greater heat sensitivity with a 4 log10 reduction in counts at 60.0°C and absence of viable cells at ≥63.0°C. These findings reiterate the need for stringent control of thermal processes in the manufacture of dairy products from raw or heat-treated (non-pasteurized) milk. © 1988, American Dairy Science Association. All rights reserved.