Pasteurizing Cold Smoked Salmon (Oncorhynchus nerka): Thermal Inactivation Kinetics ofListeria monocytogenesandListeria innocua

Abstract

Listeria monocytogenes results in potential food safety concerns in ready-to-eat refrigerated products. Cold-smoked salmon is a food considered to be at high risk for Listeria spp. contamination for which a mild heat treatment or pasteurization step might be helpful to reduce microbial levels. Cold-smoked salmon was inoculated with a cocktail of four strains (L. monocytogenes: ATCC19114, 7644, and 19113, and L. innocua: ATCC51742) and inactivation curves obtained at 58, 60, 62, 64, and 66°C using capillary tube methods. Inactivation results showed typical log linear trends (R² ≥ 0.97). D-values of L. monocytogenes and L. innocua were 0.3 to 14.1 min at 66 to 58°C, with a z-value of 5.2 to 6.5°C and activation energy of 332 to 414 kJ/mol. The nonpathogenic Listeria innocua ATCC51742 had comparable D- and z-values to the three strains of L. monocytogenes and thus can be used for validation of pasteurization processes to control L. monocytogenes in cold-smoked salmon and potentially other ready-to-eat thermolabile food products.