Purpose: The aim of this study was to improve our understanding of the pathogen's behavior in different types of milk.
Methods: This study was to evaluate the survival and metabolic activity (indexed by bioluminescence) of a chromosomally lux-marked strain of E. coli O157:H7 in raw, pasteurized and microfiltered pasteurized milk at 4 and 20°C for up to 14 d.
Results: Results showed that the population of E. coli O157:H7 and its metabolic activity decreased in all samples during storage at 4°C, with no significant differences in numbers observed between the different milk types; but metabolic activity was significantly higher (P < 0.05) in the microfiltered pasteurized milk than that in raw milk. At 20°C, survival and metabolic activity were significantly lower in raw milk compared with pasteurized milk.
Significance: Examining the role of incubation temperature has practical significance in understanding how E. coli O157:H7 and other aerobic cells behave in the food chain, from retailer fridge storage to the consumer home where the greatest risk of human infection occurs.