Research – Dynamic model to describe kinetic behavior of Listeria monocytogenes in smoked salmon

Wiley Online

In this study, the dynamic model was developed to describe cell counts of Listeria monocytogenes in smoked salmon under distribution conditions. A 9-strain mixture of L. monocytogenes was inoculated in smoked salmon at 3–4 Log CFU/g. The inoculated samples were stored at 4°C, 10°C, and 20°C for up to 16 days, and the bacterial cell counts were enumerated on PALCAM agar. The Baranyi model was fitted to the L. monocytogenes cell counts to calculate the lag phase duration (LPD; hr) and maximum growth rate (μmax; Log CFU/g/hr). LPD was 74.22 hr at 4°C, and the value was rapidly decreased to 4.84 hr at 20°C as temperature increased. μmax ranged from 0.01 to 0.13 Log CFU/g/hr, depending on the storage temperature. The kinetic parameters were fitted with secondary models as a function of temperature. Cell counts predicted by the developed model were compared with the predicted cell counts obtained at 8°C and 15°C, and the differences between predicted and observed cell counts were indicated by root mean square error (RMSE). The dynamic model was then developed with the kinetic parameters derived from the secondary model and simulated the L. monocytogenes growth. RMSE (0.368) indicates that the model performance was appropriate. These results suggest that the developed kinetic models can be useful in predicting the fates of L. monocytogenes in smoked salmon under the dynamic conditions of storage temperature and time.

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