Effect And Mechanism Of Inactivation Of High Pressure Carbon Dioxide On Escherichia Coli

Sterilization of bioactive products is one of the most important operations to food industry. The traditional thermal sterilization methods are restricted because of their shortages. Recently, non-thermal treatment has been more and more regarded along with the standard of living improved and the need of high quality and safety foods increased. Sterilization with CO2 at high pressure is a non-thermal process which has remarkable effect. It has a lot of advantages such as no residual impurity, no contamination, few alimentation loss and security.1. Escherichia coli （E. coli） is inactivated remarkably by High Pressure Carbon Dioxide （HPCD） at 25～45°C and 10 MPa～50MPa. The effect of inactivation is related with different treatment time, pressure and temperature. The rate of inactivation is slower at the initial stage and increases sharply at the later stage.2. Increasing pressure and temperature is propitious to better effect of inactivation.3. Biologic parameters of E. coli been treated by HPCD at 25～45°C and 10 MPa～50MPa were studied. Finally we chose Gompertz model for studying the biologic parameters. The rates of reduction（μ） were ranged from -0.100～-0.298 min^-1, the phase of disappearance（λ） ranged from42.3～139.8 min.4. Mechanism of E. coli been treated by HPCD were studied. The result shows that E. coli cells after HPCD treatment are subjected to injury on membranes so as to induce a leakage of intracellular materials.5. On the other hand, the lowering of pH due to the penetration of CO2 induced the inactivation of several enzymes, which leads to the inhibition of certain metabolic and regulating processes.