INACTIVATION of<i>SACCHAROMYCES CEREVISIAE</i>IN APPLE JUICE BY SQUARE‐WAVE and EXPONENTIAL‐DECAY PULSED ELECTRIC FIELDS

Abstract

With equivalent electrical energy input, inactivation of microorganisms by pulsed electric fields depends on pulse waveform. Exponential‐decay and square‐wave pulsed electric fields were selected to treat Saccharomyces cerevisiae suspended in apple juice. A parallel‐plate static treatment chamber with 25 ml volume and 0.95 cm electrode gap was used. Peak electric field and pulse electric energy input were 12 kV/cm and 260 Joules per pulse for both waveforms. Both waveforms were found effective in the microbial inactivation. However, inactivation of S. cerevisiae treated with square‐wave pulses was greater than yeast treated with exponential‐decay pulses. For the purpose of food pasteurization, square‐wave pulsed electric fields may result in significant energy savings compared to exponential‐decay pulses.