Mathematical modeling of Salmonella typhimurium inactivation under high hydrostatic pressure at different temperatures

Inactivation curves of Salmonella typhimurium under high-hydrostatic pressures (HHPs) (200, 250, 300 and 350 MPa) at different temperatures (15, 25, 35 and 45 °C) in tryptone soy broth were analyzed using the modified Gompertz model. The phase of disappearance (time for inactivation of all cells, λ) and the inactivation rate (μ) of S. typhimurium were inversely related. Inactivation rates of S. typhimurium were higher (P < 0.05) at 45 °C than 15, 25 and 35 °C under HHPs from 200 to 350 MPa. The μ values were −2.66, −6.06, −7.67 and −7.99 min−1 at 200, 250, 300 and 350 MPa HHP treatments, respectively, at 45 °C. A negative μ value (always negative) indicates that an increase (become more negative) in μ with increasing pressure or temperature is related to the S. typhimurium inactivation process. The μ values were also increased with increasing temperature from 15 to 45 °C at same treated pressures. Increased pressure and temperature had significant effects on the survival of S. typhimurium. The temperature dependence of the inactivation rate constant was analyzed based on the Arrhenius, linear and square-root models. The pressure sensitivity (low Eμ) determined based on the Arrhenius model was lower at high pressure. Eμ (activation energy) value was 1.94 kJ/mol at 350 Mpa, and 42.88, 12.99 and 3.73 kJ/mol at 200, 250 and 300 MPa, respectively. Results of this study enable the prediction of microbial inactivation exposed to HHPs at different temperatures.