Surface pasteurization of vacuum-sealed precooked ready-to-eat meat products

Pathogens may contaminate ready-to-eat meat products after cooking but before packaging. Listeria monocytogenes is a formidable contaminant in the food processing environment and is relatively heat resistant compared with other non-spore-forming pathogens. As a consequence, this microorganism is commonly chosen for evaluation in postpackage pasteurization studies. The aim of this study was to review information on the thermal surface pasteurization of vacuum-sealed precooked ready-to-eat meat products, bearing in mind the conditions of commercial production lines, and to formulate a guideline for pasteurization intensity. Review of the literature revealed that fewer microorganisms were killed at the product surface than would be expected based on the results of volumetric thermal resistance studies. Mathematical modeling studies indicated that this low kill might be due to surface imperfections that shield bacteria from the heat. More information on contamination with L. monocytogenes (and other possible pathogens) in process lines and their potential migration into product surface irregularities is urgently required. Studies involving destructive sampling (surface shaving) methods and inoculation with pathogens, both at realistic and inflated levels, should be performed with various product types. Published reports suggest that postpackage pasteurization of fully cooked meat products (weighing up to 9 kg) by water submersion (96 degrees C) for about 10 min should achieve a 2- to 4-log destruction of L. monocytogenes on the product surface. If heating at this temperature and duration is not feasible for product quality or logistic reasons, the inherent bacteriological stability of the product should be increased so that the intensity of surface pasteurization can safely be reduced.