Purpose: In this study, kinetic models and a dynamic model were developed to predict the kinetic behavior of Salmonella in Napa cabbage kimchi under changing temperature.
Methods: A mixture of Salmonella (Salmonella Typhimurium NCCP10812, Salmonella Agona NCCP12231, Salmonella Enteritidis NCCP12243 Salmonella enterica KACC11595, and Salmonella Montevideo NCCP10141) was inoculated to Napa cabbage kimchi at 4 log CFU/g. The samples were then stored at 4°C (16 days), 10°C (10 days), 15°C (6 days), 25°C (3.5 days), and 30°C (2 days). Salmonella and lactic acid bacterial cell counts were enumerated on xylose lysine deoxycholate agar, and de Man, Rogosa and Sharpe agar, respectively. The kinetic parameters such as growth rate or death rate (log CFU/g/h), and lag phase duration or shoulder period (h) were calculated by the Baranyi model, and they were then fitted to a polynomial model. A dynamic model was developed, and root mean square error (RMSE) was estimated to validate model performance.
Results: Lactic acid bacterial growth influenced Salmonella growth during fermentation. Growth rate and death rate values calculated by the Baranyi model were increased (P<0.05), but lag phase duration and shoulder period were decreased (P<0.05) when storage temperature increased. A polynomial model was appropriate to describe the effect of temperature on the kinetic parameters, and developed dynamic model was also appropriate to describe the fate of Salmonella under changing temperature. RMSE indicated that the developed models had a good performance.
Significance: These results indicate that the developed models should be useful in predicting the kinetic behavior of Salmonella in Napa cabbage kimchi at changing temperatures.