Degradation of anthocyanins in sour cherry and pomegranate juices by hydrogen peroxide in the presence of added ascorbic acid

Effects of hydrogen peroxide in the presence of ascorbic acid on the degradation of sour cherry and pomegranate juice anthocyanins were studied at three H2O2 concentrations (4.65, 6.98 and 9.31 mmol l(-1)) and two ascorbic acid concentrations (60 and 80 mg l(-1)) at 20 degreesC. Degradation of anthocyanins by H2O2, was fitted to first-order reaction kinetics in sour cherry and pomegranate juices. A similar degradation pattern was found at the 60 and 80 mg ascorbic acid levels for pomegranate juice. Degradation of sour cherry anthocyanins at the 60 mg ascorbic acid level was fitted to a second-order reaction kinetic, whereas it was a first-order reaction kinetic after a lag period occurred at the 80 mg level. Ascorbic acid, at 80 mg l(-1), markedly accelerated the degradation of anthocyanins in sour cherry juice at all the H2O2 concentrations studied. In contrast, ascorbic acid, at both 60 and 80 mg l(-1), protected the anthocyanins from the degradation by H2O2 in pomegranate juice. (C) 2002 Elsevier Science Ltd. All rights reserved.