Thermal inactivation of foodborne pathogens and the USDA pathogen modeling program

The use of heat to inactivate foodborne pathogens is a critical control point and the most common means for assuring the microbiological safety of processed foods. A key to optimization of the heating step is defining the target pathogens' heat resistance. Sufficient evidence exists to document that insufficient cooking, reheating, and/or subsequent cooling are often contributing factors in food-poisoning outbreaks. Accordingly, the objective of thermal processing is to design sufficient heating regiments to achieve a specific lethality for foodborne pathogens in foods. The effects and interactions of temperature, pH, sodium chloride content, sodium pyrophosphate, and sodium lactate concentration are among the variables that were considered when attempting to assess the heat inactivation kinetics of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., and spores of non-proteolytic Clostridium botulinum. Incorporation of these multiple barriers usually increases the sensitivity of pathogens to heat, thereby reducing heat requirements and ensuring the safety of ready-to-eat food products. Complex multifactorial experiments and analysis to quantify the effects and interactions of additional intrinsic and extrinsic factors and development of ''enhanced'' predictive models are underway to ensure the microbiological safety of thermally processed foods. Predictive inactivation kinetics (thermal death) models for foodborne pathogens have been converted into an easy-to-use computer program that is available on the USDA-Eastern Regional Research Center website. These models should aid in evaluating the safety of cooked products and are being used as building blocks for microbial risk assessment.