Modeling the thermal inactivation of non-pathogenic and avian-pathogenic Escherichia coli in broiler mash feed with high initial moisture content using a lab-based circulating water bath

Abstract

The Food Safety Modernization Act (FSMA) has stimulated the need for research into feed sanitation practices for feed producers, particularly breeder and backyard flocks. Feed can be a vector for poultry pathogens, such as Escherichia coli (E. coli) transmission to poultry, and appropriate feed manufacturing can help mitigate the feed pathogens with thermal treatments. This study aimed to apply existing models to quantify the thermal inactivation kinetics of two strains of E. coli during thermal processing between 75 and 95°C. Two-grams of feed sample were added with 200 µL of one of the two Nalidixic acid (NaL) adapted E. coli strains and submerged in a circulated water bath set at 75, 80, 85, 90, and 95°C, for heating between 0 and 180 s. United States Department of Agriculture (USDA) IPMP-Global fit software was used to calculate d-values from Weibull models and z-values from Linear models. Weibull model d-values were 19.80, 12.80, 10.40, 8.70, and 8.06 s for the APEC, and 8.00, 8.55, 5.30, 5.96, and 4.77 s for the non-pathogenic E. coli when heated at 75, 80, 85, 90, and 95°C, respectively. The z-values from Linear models were 51.6 and 81.3°C for APEC and non-pathogenic E. coli, respectively. Our results indicate the non-pathogenic E. coli may not be an ideal candidate for use as a pathogenic E. coli surrogate due to its lower thermal resistance than the tested APEC strain. However, these data validate the Linear and Weibull models are appropriate for predicting thermal inactivation of E. coli in broiler mash feed with a higher initial moisture content.