Thermal Inactivation of Listeria monocytogenes on Ready-to-Eat Turkey Breast Meat Products during Postcook In-Package Pasteurization with Hot Water

Abstract

The inactivation of Listeria monocytogenes during postcook in-package pasteurization was evaluated for fully cooked turkey breast meat products (4-kg packages). The products were surface-inoculated to contain 10⁷ CFU of L. monocytogenes per cm² of product surface. The inoculated products were vacuum-packaged in different thicknesses (0.08 to 0.33 mm) of packaging films and treated with hot water at 96°C. After heat treatment, the products were immediately cooled in an ice water bath at 0°C. The relationship between heating time and product surface temperature was determined for different thicknesses of packaging films. The effectiveness of heat treatment for inactivating the pathogen was affected by product surface roughness. About 50 min of heating time was needed to achieve a thermal kill of 7 log₁₀ CFU/cm2 on products with surface roughness up to 15 mm in depth. The cooling time needed after a heat treatment increased with an increasing endpoint temperature of the heated product and the heat penetration depth reached in the product. The cooling time needed to cool the product from 71°C to 4°C was about 2.5-fold the heating time.