Process lethality and product yield for chicken patties processed in a pilot-scale air-steam impingement oven

Chicken breast patties were processed in a pilot-scale air-steam impingement oven to a patty center temperature of 55 to 80 degrees C. Thermal processing was conducted at an air temperature of 149 degrees C, an air velocity of 7 to 13 m3/min, and a wet bulb temperature of 39 to 98 degrees C. From thermal histories, the total process lethality of the patties was calculated for Salmonella spp. and Listeria innocua using the previously published z-values. The effect of product temperature, wet bulb temperature, and air velocity on process lethality was analyzed using a regression model. The process lethality of Salmonella spp. and L. innocua in the cooked chicken patties was correlated to the patty center temperatures and cooking conditions. The process lethality was strongly correlated to product temperature and was affected by cooking conditions. Process lethality started to increase rapidly at the product temperature around 67 degrees C. Regression analysis was used to correlate the product yield with cooking conditions. Depending on air velocity, product yield decreased 10 to 14% with increasing endpoint temperature from 55 to 80 degrees C and increased 2 to 9% with increasing wet bulb temperature from 39 to 98 degrees C. The effect of air velocity on the yield interacted with product temperature and wet bulb temperature.