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

Akyol, Çağdaş
In this study, the efficiency of high-pressure treatment (HHP, 250 - 450 MPa) with the combination of heat treatment (20 - 70oC) on peroxidase (POD) and lipoxygenase (LOX) inactivation in green beans, green peas and carrots was investigated for blanching purposes. Two steps treatments were also performed by pressurization at 250 MPa at 20°C for 15- 60 min and then by water blanching at 40-70°C. For green beans, 25 % residual activity was obtained by water blanching at 50°C for 15 min after the pressurization at 250 MPa for 60 min. The enzyme inactivation in green peas was 78 % with water blanching at 50oC for 30 min after holding at 250 MPa for 60 min. When the carrots were water blanched at 50°C for 30 min after HHP treatment at 250 MPa for 15min, 13 % residual activity was obtained. During the experiments, the stability gain or the activation of latent form of the enzymes were observed prior to inactivation. For carrots, LOX activity could not be measured. For green beans, 22 % LOX inactivation was obtained by holding at 250 MPa for 15 min and then by water blanching at 40°C for 5 min. For green peas, the multiple treatment of 250 MPa for 30 min and water blanching at 50°C for 30 min provided 70% inactivation. To obtain the enzyme inactivation higher than 90 % for blanching purposes, the pressure applied must be increased.