Peroxidase inactivation and colour changes during ohmic blanching of pea puree

Abstract

Ohmic heating is an alternative fast heating method for food products. In this study, the pea puree samples were blanched ohmically and conventionally. The ohmic blanching was performed by application of four different voltage gradients in the range of 20-50 V/cm. The puree samples were heated from 30 degrees C to 100 degrees C and held at 100 degrees C to achieve adequate blanching. The conventional blanching was performed at 100 degrees C water bath. The ohmic blanching applied by using 30 V/cm and above voltage gradient inactivated peroxidase enzyme at less time than the water blanching. The ohmic blanching at 50 V/cm gave the shortest critical inactivation time of 54 s with the best colour quality. First order reaction kinetics adequately described the changes in colour values during ohmic blanching. Hue angle is the most appropriate combination (R-2 = 0.954), which describes closely the reaction kinetics of total colour changes of pea puree for ohmic blanching at 20 V/cm. (c) 2005 Elsevier Ltd. All rights reserved.