Mathematical modeling of Escherichia coli inactivation under high-pressurecarbon dioxide

Inactivation curves of Escherichia coli under high carbon dioxide pressures (2.5, 5.1, 7.6 and 10.1 MPa) at different temperatures (20, 30, 40 and 45 degreesC) were analyzed using the modified Gompertz model. The phase disapp earance (time for complete inactivation of all cells, lambda) and the inact ivation rate (mu) of E. coli were inversely related. Inactivation rates (mu ) of E. coli were higher at 45 degreesC under 10.1 MPa CO2 pressure than at 25, 30 and 40 degreesC under 2.5, 5.1 and 7.6 MPa CO2 pressure. Increased pressure and temperature had significant effects on the survival of E. coli . The temperature dependence of the inactivation rate constant was analyzed based on the Arrhenius, linear and square-root models. The temperature sen sitivity (high Ed determined based on the Arrhenius model was higher at hig h temperatures. E-mu (activation energy) value was -186.56 Kjoule/mol at 10 .1 Mpa, and -137.24, -167.25 and -183.80 Kjoule/mol at 2.5, 5.1 and 7.6 MPa , respectively. Results of this study enable the prediction of microbial in activation exposed to different CO2 pressures and temperatures.