[Thermal inactivation model of Listeria monocytogenes in ground beef].

Objective: To set up suitable kinetic models for the evaluation of heat inactivation rate of Listeria monocytogenes in ground beef.

Methods: Ground beef, inoculated with 3 strains of L. monocytogenes, was subjected to heating at 55 degrees C, 57.5 degrees C, 60 degrees C, 63 degrees C, 66 degrees C or 70 degrees C to develop the isothermal kinetic models. The survival curves were fitted with modified Gompertz model after the bacterial counts were decreased from 10(9) CFU/g to 10(3) CFU/g. Natural logarithm of mu (the relative inactivation rate) and M (time constant) were fitted with linear regression model. The kinetic models were validated at 59 degrees C and 64 degreeeC.

Results: We established one first-level model and one secondary-level model to predict the inactivation rate. In addition, we validated the accuracy and deviation of the models to guarantee their feasibility.

Conclusion: The models should be suitable for describing the survival of L. monocytogenes in ground beef at different temperatures, which are helpful for the control of the pathogens.