Survival and Growth of Salmonella and Listeria in the Chicken Breast Patties Subjected to Time and Temperature Abuse under Varying Conditions

Chicken breast patties were inoculated with a mixture of Salmonella Senftenberg, Salmonella Typhimurium, Salmonella Heidelberg, Salmonella Mission, Salmonella Montevideo, Salmonella California, and Listeria innocua. The initial inoculation of bacteria was approximately 10 7 log 10 CFU/g. The inoculated patties were processed in a pilot-scale air convection oven at an air temperature of 177°C, an air velocity of 9.9 m 3 /min, and a low (a wet bulb temperature of 48°C) or high (a wet bulb temperature of 93°C) humidity condition. The patties were processed to a final center temperature of 65 to 75°C. The survivors of Salmonella and Listeria in the processed patties were evaluated. Processing humidity affected the survivors of bacteria. More survivors of Salmonella and Listeria (>2 logs) were obtained for the patties cooked at low humidity than at high humidity. After thermal processing, the patties were stored under air, vacuum, or CO 2 at refrigerated (4°C) or thermally abused (8 to 15°C) temperatures. Storage temperature, time, and gas environment affected the bacteria growth. Higher storage temperature and longer storage time correlated to an increased growth of bacteria in the cooked chicken patties. Less Salmonella (2 logs) and Listeria (0.5 to 1 log) cells were obtained in the patties stored under vacuum than in air. Storing the patties in 30% CO 2 reduced the growth of Salmonella more than 2 log 10 CFU/g. At a CO 2 level of 15%, 1 log 10 CFU/g of reduction was obtained for Listeria in cooked chicken patties.