INACTIVATION OF MICROORGANISMS BY PULSED ELECTRIC-FIELDS OF DIFFERENTVOLTAGE WAVE-FORMS

Processing foods with HV pulsed electric fields (PEF) is a new technol ogy to inactivate microorganisms and denature enzymes with only a smal l increase in temperature. Introduction of this new technology will re place or complement conventional thermal processing methods. It will a lso provide consumers with safe, nutritious foods with fresh quality. For a given peak value of field intensity and amount of electric energ y input, PEF inactivation of microorganisms is closely related to the waveform of applied pulses. Inactivation of microorganisms was studied with different waveshapes including exponential decay, oscillatory de cay, square waves, and bipolar pulses. Microbial inactivation was test ed in a parallel-plate static treatment chamber. Treatment field inten sity ranged from 12 to 40 kV/cm while pulse length ranged from 20 to 1 80 mu s. From the microbial test results, bipolar square-wave pulses a re the most efficient in terms of microbial inactivation for commercia l PEF pasteurization.