Growth kinetics of Salmonella spp. pre- and post-thermal treatment

This paper reports estimated growth kinetic parameters for a cocktail of stationary phase Salmonella serotypes, pre- and post-thermal inactivation treatment. Cells were grown in brain-heart infusion broth at 25 or 37 °C and then destruction of the cells was quantified at 55 °C using a submerged coil heating apparatus. The surviving cells (about 1-2 log10 cfu/ml) were subsequently grown at 25 or 37 °C. The results indicated that lag phase duration times for the post- heat treated cells increased at 25 and 37 °C by about 6.2 h and at least 3 to 4 h, respectively, and thus the increases appear to be truly different. However, when considering the ratios of the lag phase duration times for post-treated to pre-treated cells, a significant difference was not found, where estimated ratios could exceed 4. Estimated exponential growth rates, EGR, were not affected by the treatment, where for 37 °C, EGR was estimated to be 0.9 log10 (cfu/ml)/h, and at 25 °C, the EGR was estimated at 0.45 log10 (cfu/ml)/h.