Peracetic acid efficacy and decay kinetics in poultry processing under chiller conditions

Pathogens on poultry products continue to pose critical public health risks. While chilling is a critical control point, the mechanisms of sanitizer efficacy in terms of pathogen and organic load, sanitizer levels, and exposure duration have not been clearly quantified. Moving beyond descriptive sanitizer-pathogen reduction experiments, we utilized experimentally-informed-mathematical-modeling to determine pathogen dynamics during chilling. Under realistic conditions in 10-L chiller tanks, whole chicken carcasses were exposed to peracetic acid (PAA; 70 and 200 mg⋅L^-1) with process water parameters and PAA levels monitored up to 60 min. Additionally, the shedding and survival of a five-strain cocktail of poultry plant derived Salmonella enterica serovars, at high and low loads, with exposure to PAA (0-75 mg⋅L^-1) for up to 10 min, in the presence/absence of inoculated chicken thighs, were measured. A mathematical model for PAA decay and pathogen shedding/inactivation was developed. Results indicate total dissolved solids (TDS) predict PAA decay more consistently than chemical oxygen demand (COD), with accurate forecasting of PAA level changes in the pre/main chiller of a high-speed poultry processing plant in North America. Without organic load, residual PAA (1 mg⋅L^-1) inactivated bacteria given sufficient exposure time, although PAA levels >5 mg⋅L^-1 were essential for rapid inactivation. With organic load, initial PAA concentration (> 40 mg⋅L^-1) and exposure time (> 2 min) were critical for bacterial reduction, with model results contrasting when shed or sanitizer inactivation dominate. The data and insights from this study provide novel tools for processors to improve pathogen control during chilling.