EFFECTS OF HIGH-PRESSURE PROCESSING ON POLYPHENOLOXIDASE ENZYME-ACTIVITY OF GRAPE MUSTS

The effects of high pressure processing (300, 600, 900 MPa for 2, 6 an d 10 min) on the activity of polyphenoloxidase (PPO) enzymes were eval uated in a synthetic must to which an enzymatic extract obtained from grapes had been added, and in a white grapes must. Despite the fact th at the results vary as a function of the medium studied, it could be s een that the PPO typical of the musts could only be partly inactivated by high pressure treatment (300-600 MPa). On the other hand, at highe r pressures (900 MPa), PPO enzymatic residual activity was clearly low er(1 to 16%) in both the synthetic and the white must. (C) 1997 Elsevi er Science Ltd.