Validating a physically heat-treated process for poultry litter in industry settings using the avirulent Salmonella surrogates or indicator microorganisms

Poultry litter is an excellent source of nutrients for the growth of agricultural crops. To reduce the microbiological risks associated with the use of raw poultry litter as a soil amendment or organic fertilizer, heat treatment is recommended to reduce or eliminate potential pathogenic microorganisms. Our recent studies have demonstrated that thermal resistance of Salmonella in chicken litter is increased significantly when cells are adapted to desiccation or when aged chicken litter with low moisture content is heat treated. By increasing the moisture level in chicken litter or applying a two-step heat treatment (wet heat followed by dry heat), Salmonella can be inactivated more rapidly. Our preliminary results indicate a good correlation in thermal inactivation rates between desiccation-adapted Salmonella and indigenous enterococci in chicken litter, suggesting enterococci as a potential indicator for heat process validation. We will collaborate with two large poultry litter processors to validate their heat-treatment processes in industrial settings by using Salmonella surrogate and indicator microorganisms identified in this study. Results from this research will provide some valid guidelines and tools for the fertilizer industry to produce Salmonella-free heat-treated poultry litter, thereby ensuring safe production of fresh produce.