Microbiological conditions of moisture-enhanced pork before and after cooking

Abstract

Substantial numbers of aerobic bacteria but few coliforms or Listeria spp. and no Escherichia coli were recovered from both swab samples and brines circulated in cleaned equipment used for injecting pork loins. After meat was processed for 30 or 60 min, the numbers of aerobic bacteria in brines had increased by >1 log unit, to about 4.5 log cfu ml −1, but coliforms were <2 and E. coli and Listeria spp. were <1 log cfu ml −1. The numbers of bacteria on the surfaces of pork loins before and after injection of the meat were similar. No bacteria were recovered from the deep tissues of the uninjected meat, but aerobic bacteria were recovered at log-mean numbers of 2.1 log cfu g −1 and coliforms at log-total numbers of 1.2 log cfu 25 g −1 from 25 samples of deep tissues of injected meat. Aerobic bacteria were recovered at log total numbers of 1.0 log cfu 25 g −1 from 25 samples of injected pork cooked to a central temperature of 61 °C, but no bacteria were recovered from the deep tissues of meat cooked to 70 °C. The findings suggest that moisture-enhanced pork cooked to a medium rare condition can be microbiologically safe.