Growth kinetics of Listeria monocytogenes in broth and beef frankfurters -: Determination of lag phase duration and exponential growth rate under isothermal conditions

The objective of this study was to develop a new kinetic model to describe the Isothermal growth microorganisms. The new model was tested with Listeria monocytogenes in tryptic soy broth and frankfurtes, compared with 2 commonly used models--Baranyi and modified Gomportz models. Bias factor (UP), accuracy (AF), and root mean square errors (RMSE) were used to evaluate the 3 models. Either In broth or In frankfurter samples, there were no significant differences in BF (approximately 1.0) and AF(1.02 to 1.04) among the 3 models broth, the mean RMSE of the new model was very close to that of the Bamnyl model, but significantly lower the of the modified Gompertz mod.-A. However, in frankfurters, there were to significant differences in the mean values among the 3 models. These results suggest that these models are equally capable of describing isothermal bacterial growth curves. Almost identical to the Baranyi model in the exponential and stationary phases, the model has a more identifiable lag phase and also suggests that the bacteria population would increase exponentially until the population approaches to within 1 to 2 logs from the stationary phase. In general, there Is no sign difference In the means 911 the lag phase duration and specific growth rate between the new and Barany! a but both are significantly lower than those determined from the modified Gompertz models. The model devil in this study Is directly derived from the isothermal growth characterifitics and is more accurate in describing kinetics of bacterial growth in foods.