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 degrees Celsius and then destruction of the cells was quantified at 55 degrees Celsius using a submerged coil heating apparatus. The surviving cells (about 1-2 log(10) cfu/ml) were subsequently grown at 25 or 37 degrees Celsius. The results indicated that lag phase duration times for the post- heat treated cells increased at 25 and 37 degrees Celsius 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 degrees Celsius, EGR was estimated to be 0.9 log(10) (cfu/ml)/h, and at 25 degrees Celsius, the EGR was estimated at 0.45 log(10) (cfu/ml)/h.