Research on effect of ultra high pressure treatment on activity of PPO in fresh peach juice

As the pressure increased,the activity of PPO in the juice reduced slowly in the pressure range of 200~500MPa,and 400 MPa could activate PPO in the juice.The effect of pressure on the inactivation of PPO became remarkable when it was above 600 MPa.Adding VC activated PPO in the juice when the pressure was below 500 MPa but inactivated it when the pressure was above 600 MPa or combined with heating.The activity of PPO in the juice decreased gradually with the rise of heating temperature and the extension of pressure holding time.The treatment above 500 MPa and 60℃ or 750 MPa and 50℃ could inactivate the activity of PPO by 61%.PPO in the peach juice was hardly inactivated by high pressure.