INACTIVATION OF PEROXIDASE, LIPOXYGENASE, AND POLYPHENOL OXIDASE BY MANOTHERMOSONICATION

The combined effects of heat and ultrasonic waves operating at absolut e pressures between 1.5 and 7.2 kg/cm(2) on peroxidase, polyphenol oxi dase, and lipoxygenase inactivation have been studied over a broad ran ge of temperatures, static pressures, and ultrasound amplitudes. A syn ergistic effect which can substantially reduce enzyme resistance and t he heat treatment required for inactivation was observed in all cases. The peroxidase z value, estimated at 26 degrees C, was not changed by the combined treatment, but that of lipoxygenase increased from 4.2 d egrees C (heat treatment) to 6.8 degrees C (combined treatment). The e nzyme destruction efficiency of the combined process greatly increases with ultrasonic wave amplitude; decimal reduction times at constant t emperature decreased logarithmically with increasing amplitudes. Stati c pressure does not seem to affect much the destructive effect of the combined process. This combined treatment could help-to solve, in milk , juices, and other drinks, problems caused by thermostable enzymes.