Purpose: A study was undertaken to develop a model for predicting behavior of Salmonella 8,20:-:z6 in chicken meat during cold storage and to determine how well the model predicts behavior of other serotypes of Salmonella stored under the same conditions.
Methods: Ground chicken thigh meat (0.75 cm3) was inoculated with 1.7 log of Salmonella followed by storage for 0 to 8 days at -8 to 16°C. An automated mini-most probable number method was used for enumeration of Salmonella. Commercial software (NeuralTools) was used to develop a multi-layer feedforward neural network model with one hidden layer of two nodes. Model performance was evaluated using the acceptable prediction zone method.
Results: Number of Salmonella in ground chicken thigh meat stayed the same (P > 0.05) during 8 days of storage at -8 to 8°C but increased (P < 0.05) over time of storage at 9 to 16°C. The proportion of residuals in an acceptable prediction zone (pAPZ) from -1 log (fail-safe) to 0.5 log (fail-dangerous) was 0.939 for data (n = 426) used in model development. The model had pAPZ of 0.944 or 0.954 when it was extrapolated to test data (n = 108/serotype) for other serotypes (Typhimurium var 5-, Kentucky, Typhimurium, Thompson) of Salmonella in ground chicken thigh meat stored for 0 to 8 days at -4, 4, 12, or 16°C.
Significance: A pAPZ ≥ 0.7 indicates that a model provides predictions with acceptable bias and accuracy. Thus, results indicated that the model provided valid predictions of survival and growth of Salmonella 8,20:-:z6 in ground chicken thigh meat stored for 0 to 8 days at -8 to 16°C and that the model was validated for extrapolation to four other serotypes of Salmonella.