Inactivation of orange juice peroxidase by high-intensity pulsed electric fields as influenced by process parameters

The inactivation of orange juice peroxidase (POD) under high-intensity pulsed electric fields (HIPEF) was studied. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency and pulse width) were evaluated and compared with conventional heat pasteurization. Samples were exposed to electric field strengths from 5 to 35 kV cm(-1) for up to 1500 mu s using square wave pulses in mono- and bipolar mode. Effect of pulse frequency (50-450 Hz), pulse width (1-10 mu s) and electric energy on POD inactivation by HIPEF were also studied. Temperature was always below 40 degrees C. POD was totally inactivated by HIPEF and the treatment was more effective than thermal processing in inactivating orange juice POD. The extent of POD inactivation depended on HIPEF processing parameters. Orange juice POD inhibition was greater when the electric field strength, the treatment time, the pulse frequency and the pulse width increased. Monopolar pulses were more effective than bipolar pulses. Orange juice POD activity decreased with electric energy density input. The Weibull distribution function adequately described orange juice POD inactivation as a function of the majority of HIPEF parameters. Moreover, reduction of POD activity related to the electric field strength could be well described by the Fermi model. (c) 2005 Society of Chemical Industry.