Effect of high hydrostatic pressure treatment on post processing antioxidant activity of fresh Navel orange juice

Total antioxidant activity of high pressure processed (600 MPa, 40 °C, 4 min) compared to thermally pasteurised (80 °C, 60 s) fresh Navel orange juice was studied as a function of storage at different isothermal conditions (0-30 °C). The contribution of ascorbic acid - among the other antioxidant compounds of orange juice - to the total antioxidant activity was also evaluated. The reaction rate constant of nth order kinetics of the decolourisation of ABTS radical cation solution, after addition of orange juice, was used as a measure of the total antioxidant activity. A mathematical description of the above reaction rate constant as a function of storage temperature and time was established. Total antioxidant activity of both juices decreased during storage mainly due to ascorbic acid loss. High pressure treatment led to a better retention of the antioxidant activity of orange juice compared to conventional pasteurisation.