Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

Abstract

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250-450 MPa at 20-50 ◦ C for 15-60 min. In the second part, two steps treatments were performed as water blanching at 40-70 ◦ C for 15 and 30 min after pressuriza- tion at 250 MPa and 20 ◦ C for 15-60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 ◦ C and then it decreased to 9% at 60 min. When the carrots were wa- ter blanched at 50 ◦ C for 30 min after HHP treatment of 250 MPa at 20 ◦ C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanch- ing at 50 ◦ C for 15 min after pressurization at 250 MPa and 20 ◦ C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 ◦ C for 15 or 30 min, wa- ter blanching at 60 ◦ C for 30 min provided 2-3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 ◦ C for 30 min