Reaction Kinetics Analysis of Chemical Changes in Pressure-Assisted Thermal Processing

Pressure-assisted thermal processing (PATP) at T < 100 degrees C can be used when enzyme inactivation and pasteurization by high pressure processing (HPP) is not feasible due to long processing times while PATP at T > 100 degrees C can be used when bacterial spores inactivation is necessary. In PATP, the adiabatic compression/decompression heat increases/decreases temperature almost instantaneously, and the simultaneous application of high pressure (similar to 600-700 MPa) and temperature (similar to 100-120 degrees C) accelerates spore inactivation. PATP effects on chemical changes are analyzed using a reaction kinetics approach including activation volume (V-a) and activation energy (E-a) values. Reaction rates increase or decrease with pressure for negative or positive V-a values, respectively, while rate temperature and pressure sensitivity depends on the magnitude of E-a and V-a values, respectively. The complex effects of food matrix, pH, dissolved oxygen, and presence of antioxidants show that optimization of vitamin, pigment and flavor retention while ensuring PATP microbial and enzyme inactivation will require substantially more chemical reaction kinetics research.