Inactivation Kinetics Of Lipoxygenase Inpressurized Raw Soymilk And Soymilk Fromrnhigh-pressure Treated Soybeans

摘要

High hydrostatic pressure (HHP) treatment (275, 345, 483, 550 and 620 MPa), combined with thermal treatment (19, 50, 65, 70 and 80C), was applied for selected times to raw soymilk and to previously soaked soybeans before preparation of soymilk. Lipoxygenase (LOX) activity in HHP-treated raw soymilk was described using a first-order kinetics model. At low or moderate pressures, alone or in combination with thermal treatment, LOX activity exhibited high stability. Soymilks treated at 550 MPa exhibited high LOX inactivation rate constant values. Temperature dependence on the inac-tivation rate constants of soymilk treated at 550 MPa indicated that high activation energy was required to inactivate the enzyme in soymilk from HHP-treated soybeans compared with that for HHP-treated raw soymilk. Lipoxygenase activity was not detected in soymilk from HHP (620 MPa and 80C) treated soybeans.