Inactivation of peach polyphenoloxidase by exposure to pulsed electric fields

The effect of exponential decay pulsed electric fields on peach (var. Miraflores) polyphenoloxidase (PPO) was evaluated. Electric field intensities ranged from 2.18 to 24.30 kV/cm. Pulses of 0.02 and 0.08 ms width were applied in mono- and bipolar mode. A 70% maximum reduction in enzymatic activity was achieved after 5 ms using 0.02 ms width pulses in bipolar mode at 24.30 kV/cm. Peach PPO activity decreased following an exponential decay kinetic model. Rate constants ranged from 9.0 to 138 mus(-1) in monopolar mode, and from 8.7 to 235 mus(-1) in bipolar mode. An exponential decay model may describe the relationship between residual PPO and input electric energy.