The effects of different thermal and thermosonication blanching treatments on the inactivation of peroxidase (POD) and the retention of total chlorophyll in argy wormwood leaves were studied. Inactivation of POD followed a biphasic first-order model under thermal blanching treatments below 90 A degrees C while a first-order model at 90 A degrees C. In contrast, for thermosonication treatments, the inactivation kinetics of POD fit a first-order model well for all the temperatures tested. Thermosonication treatment was found to inactivate POD faster and retain more of the total chlorophyll than thermal blanching treatment. A thermosonication protocol using ultrasonic intensity of 11.94 W/cm(2) at 85 A degrees C for 60 s was found to be the most suitable protocol for blanching the argy wormwood leaves. This protocol inactivated 92. 7 % POD while retaining 96.7 % of total chlorophyll.