Survival and growth of Escherichia coli O157:H7, Yersinia enterocolitica and Salmonella enteritidis on decontaminated and untreated meat. Meat Sci

Decontamination of meat or carcasses may have an eect in reducing the number of pathogens. Recontamination with other pathogens during cutting or packaging may, however, result in higher growth on decontaminated than on untreated meat due to the lack of competing non-pathogenic microorganisms. In this study we compared the growth of pathogens during storage at 10C (worst case condition) on untreated meat and meat that had been decontaminated by steam vacuuming combined with spraying with 0.2 M lactic acid. Salmonella enteritidis inoculated on chicken multiplied quickly and reached log 7 cfu per cm2 after 4 days of aerobic storage at 10C, but growth was not significantly higher on decontaminated than on untreated chicken. The number of Yersinia enterocolitica inoculated on decontaminated pork skin reached log 9 cfu per cm2 after 5 days of aerobic storage at 10C. Overall, growth on vacuum-packed decontaminated and untreated pork under the same conditions was not significantly dierent, although there tended to be less growth on the untreated samples. The number of Escherichia coli O157:H7 on decontaminated beef increased by nearly 3 log cycles after 5 days of aerobic storage at 10C compared to only a 1 log cycle increase on untreated beef. For the vacuum-packed beef, growth of E. coli O157:H7 on the fresh meat was very slow, while there was about a 3 log increase on the decontaminated beef. A higher average growth on the decontaminated beef was also found in an experiment with a very low inoculum (27 cfu per cm2). During storage of vacuum-packed samples there was multiplication of E. coli O157:H7 on the decon-taminated beef, but virtually none on the untreated beef. This study shows that multiplication of S. enteritidis on chicken and Y