A Predictive Model for the Inactivation of Listeria innocuain Cooked Poultry Products during Postpackage Pasteurization

Contamination of Listeria monocytogenesin ready-to-eat poultry products poses potential risk of listeriosis to the public. To control the level of Listeriacontamination, attention has been focused on the postpackage pasteurization of fully cooked poultry products. In this study, we sought to develop a model to predict the thermal inactivation of L. monocytogenesin chicken drumettes during postpackage hot water pasteurization. Fully cooked chicken drumettes were inoculated with Listeria innocuaas a surrogate microorganism for Listeria monocytogenes,vacuum packaged, and treated in hot water baths at 60, 70, 80, and 90 u C for different heating times. Experimental results showed that a 7-log CFU/g reduction of L. innocuaoccurred at 54, 28, 18, and 10 min at 60, 70, 80, and 90°C, respectively. The Weibull model was used to fit the survival curves of L. innocuaat each heating temperature. The root mean square errors and residual plots indicated good agreements between the predicted and observed values. The predictive model was further validated by predicting a new data set generated in the pilot-plant tests. Model performance was evaluated by the acceptable prediction zone method, and the results indicated that the percentages of acceptable prediction errors were 100, 100, 82.4, and 87.5% at 60, 70, 80 and 90°C, respectively, which were all greater than the threshold acceptable value of 70%, indicating good performance of the model. The developed predictive model can be used as a tool to predict thermal inactivation behaviors of L. monocytogenesin ready-to-eat chicken drumettes products.