Purpose: This study developed a dynamic model to predict the fates of Salmonella in diced white radish kimchi during fermentation.
Methods: Diced white radish kimchi was prepared in laboratory by a traditional method. A 5-strain mixture of Salmonella (Typhimurium NCCP10812, Agona NCCP12231, Enteritidis NCCP12243, S. enterica KACC11595, and Montevideo NCCP10141) was inoculated in diced white radish kimchi at 4 log CFU/g. The inoculated samples were then stored at 4°C, 15°C, and 25°C for 14 days, 2 days, and 1.5 days, respectively. Salmonella (XLD) and lactic acid bacteria (de Man, Rogosa, and Sharpe agar) was enumerated, and the observed data of Salmonella were fitted to the Baranyi model to calculate death rate (DR; log CFU/g/h) and shoulder period (h). The kinetic parameters (DR and shoulder period) were then fitted to polynomial equations, and a dynamic model was developed in accordance with primary and secondary models. To validate the performance of developed models, root mean square error (RMSE) was calculated.
Results: Salmonella did not grow at all temperatures, and the death of Salmonella started after shoulder periods as bacterial populations of lactic acid bacteria increased. From 4 to 25°C, the shoulder period was rapidly decreased (P<0.05), and DR increased (P<0.05). Developed secondary models for the kinetic parameters showed appropriate performance. As a result of validation, the performance of kinetic models was appropriate with 0.485 of RMSE. The prediction of developed dynamic model at changing temperatures was also appropriate.
Significance: These results indicate that the developed models should be useful in predicting the kinetic behavior of Salmonella in diced white radish kimchi fermentation.