High hydrostatic pressure inactivation kinetics of the endogenous lipoxygenase in crude silver carp (Hypophthalmichthys molitrix) extract

Inactivation kinetics of endogenous lipoxygenase in crude silver carp (Hypophthalmichthys molitrix) extract was studied for thermal (5080 degrees C, ambient pressure) and high hydrostatic pressure combined with heat treatment (300700MPa at 5080 degrees C) process conditions. Lipoxygenase (LOX) inactivation followed first-order kinetics at all pressuretemperature combinations used. Moreover, LOX inactivation rates became less pressure dependent with increasing pressure at all temperatures studied and also showed less temperature dependence of the enzyme inactivation rate at various high pressure levels tested. It is evident that inactivation kinetics is complex affected by both pressure and temperature. Therefore, response surface methodology (RSM) was attempted to investigate combined temperaturepressure processing conditions on LOX inactivation kinetics in crude silver carp extract samples. In conclusion, the LOX inactivation rate constant was modelled as a function of both temperature and pressure conditions by a quadratic polynomial equation as follows: k=0.2783.991E004 center dot P0.01 center dot T+6.167E006 center dot PxT+3.608E007P2+9.525E005 center dot T2 .