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 and 10min) on the activity of polyphenoloxidase (PPO) enzymes were evaluated in a synthetic must to which an enzymatic extract obtained from grapes had been added, and in a white grapes must. Despite the fact that the results vary as a function of the medium studied, it could be seen that the PPO typical of the musts could only be partly inactivated by high pressure treatment (300–600 MPa). On the other hand, at higher pressures (900 MPa), PPO enzymatic residual activity was clearly lower (1 to 16%) in both the synthetic and the white must.