Heat inactivation of thermo-resistant bacteria isolated from poultry offal

The presence of thermo-resistant bacteria in products from the rendering industry is a concern problem in the United States because only about 80% of the rendering industries use thermal processing to eliminate bacteria. The objective of this study was to determine the thermal inactivation characteristics of thermo-resistant bacteria from raw rendering materials. Ground beef with 21% protein, 19% fat, and 60% moisture was used as a model media to simulate raw rendering material. Raw animal co-products were heated at 91, 95, 96°C for 90 min, then surviving bacteria were recovered. These heat resistant isolates were inoculated into meat samples then thermally treated using a dry bath incubator. Calculations for D and Z values were determined for thermo-resistant bacteria subjected to thermal treatment at 91°C, 94°C, and 96°C. This study demonstrated that thermally resistant bacteria isolated from raw rendering materials exhibit high heat resistance for a wide range of temperature, suggesting that use of thermal processing at an optimized temperate (> 96°C) is required for an efficient removal of microbes.