Thermal Inactivation of Salmonella spp. and Listeria innocua in the Chicken Breast Patties Processed in a Pilot-Scale Air-Convection Oven

ABSTRACT: Salmonella spp. or Listeria innocua containing chicken patties were processed via a pilot-scale air-convection oven to a final temperature of 55 to 80 8C. Thermal processing was conducted at an air temperature of149 8C, an air velocity of 7.1 to 12.7 m 3 /min, and a wet bulb temperature of 39 to 98 8C. The cooking time wascorrelated with cooking conditions using a standardized least square regression model. The models were developedto correlate cooking time and the thermal inactivation of Salmonella or Listeria with cooking conditions. Thethermal lethality of Salmonella and Listeria increased with increasing product temperature and wet bulb tempera-ture. This study bridged the gap between laboratory studies and commercial applications and will help commercialprocessors to evaluate and validate their thermal processes.Key Words: poultry, Salmonella , Listeria , lethality, convection cooking Introduction T HE MARKET FOR READY - TO - EAT POUL -try products has experienced tre-mendous growth in recent years, with avariety of patties, nuggets, strips,breasts, thighs, and wings being avail-able to the consumer through retailingand catering. This tremendous growthhas led to serious concerns over thesafety of the products due to the pres-ence of pathogens, and an emphasishas been placed on the thorough cook-ing of the meat products. The USDA-FSIS current regulations require thatthe processor provide the supportinginformation for the hazard analysis anddecision-making documents associatedwith the development of HACCP plans,critical limits, selection and frequencyof monitoring, and verification proce-dures (USDA-FSIS 1999). According tothe current regulation, there are nostandard operating procedures for sci-entific and/or correlation studies. It isthe processor’s responsibility to providethe in-plant data for the scientific sup-port and to demonstrate that the estab-lishment is able to meet the parametersoutlined in the HACCP plans for theiroperation. This study aimed at evaluat-ing commercial operating conditionsand supplying useful information tocommercial processors and regulatoryagencies for the pathogen lethality vali-dations of commercial thermal pro-cesses.Previous studies indicated that manyfactors affected the pathogen thermalinactivation. Pathogen thermal inactiva-tion kinetics was different between liq-uid medium and meat substrate (Mur-phy and others 2000b). It is known thatthe laboratory evaluation of thermal in-activation of pathogens is influenced bya number of factors including tempera-ture, the pathogen strain and its history,the meat species (or medium types)and its composition, and a number ofenvironmental factors such as pH, wa-ter activity, and chemical additives(Ghazala and others 1995; Heddlesonand others 1994; Huang and others1993; Kim and others 1995; Murphy andothers 1999; Patchett and others 1996;Veeramuthu and others 1998). Inactiva-tion kinetics have been obtained for