Review of Scientific Literature Related to Survival of Pathogenic Foodborne Bacteria during Cooling of Heat-treated, RTE Meat and Poultry Products and Thawing of Frozen Raw Meat and Poultry

Objectives

To present published data on the potential survival of sporeformers during cooling and the effects of water activity, pH, sodium chloride, curing salts, and other preservatives on growth and survival of C. perfringens; and survival and growth of bacterial pathogens on raw meat during chilling.

Conclusions

Bacterial spores are not only very heat resistant but heat actually stimulates the spores to start growth. Generation times as short as 7 min have been recorded and therefore, it is important to cool cooked meats quickly to temperatures below the minimum that allows germination and growth of sporeformers. The critical temperature range for growth of B. cereus, C. perfringens, and some C. botulinum strains is approximately 10-50°C although some psychrotrophic C. botulinum strains can grow at refrigerator temperatures. Rapid chilling of animal carcasses after slaughter is important for retarding the growth of both pathogenic and spoilage bacteria. Chilling will not destroy these bacteria although viable cells of many species decrease with time during refrigerated storage. Psychrotrophic bacteria can grow at low temperatures, even in refrigerators. The most important pathogenic psychrotrophs for the meat industry are L. monocytogenes and Y. enterocolitica, both of which can grow at temperatures as low as 30°F. Psychrotrophic strains of B. cereus are mainly found in dairy products while nonproteolytic C. botulinum are usually isolated from seafood. Although psychrotrophs can grow at low temperatures, there may be a long lag phase of several hours before growth begins and a relatively long generation time at refrigeration temperatures. Given enough time, significant growth may occur. But if meat is kept at a low temperature (which permits growth of pathogens) for a relatively short time, then there may be no significant growth. Other factors, such as the drying effect on air-cooled carcasses, the presence of other bacteria, the pH of the meat, and carcass washing procedures will also affect the growth rate of pathogens.

Deliverable

Two comprehensive literature reviews were prepared and made available to industry to assist in validating cooking, cooling and thawing processes in HACCP plans.