EFFECTS OF HIGH-FIELD ELECTRIC PULSES ON THE ACTIVITY OF SELECTED ENZYMES

A compact and low cost bench-top, pulsed electric field treatment syst em was designed and developed. The unit consisted of a high-voltage pu lse generator (less than or equal to 30 kV) and a treatment chamber wi th less than or equal to 148 mi capacity. Over the set-lip voltage ran ge of 4-26 kV, 30 pulses (with instant charge reversal) were applied t o eight different enzyme solutions using a 0.3-cm electrode distance, a 13-87 kV/cm field, 0.5-Hz pulse frequency, 2-mu s pulse width and 20 degrees C process temperature. For some enzymes, activities were redu ced after the pulse treatments: lipase, glucose oxidase and heat-stabl e Lx-amylase exhibited a vast reduction of 70-85%; peroxidase and poly phenol oxidase showed a moderate 30-40% reduction whereas alkaline pho sphatase only displayed a slight 5% reduction under the conditions emp loyed. On the other hand the enzyme activities of lysozyme and pepsin were increased under a certain range of voltages. Electric pulse profi le (instant charge reversal) played a very important role in reducing the activities of various enzymes. (C) 1997 Elsevier Science Limited. All rights reserved