Involvement of blueberry peroxidase in the mechanisms of anthocyanin degradation in blueberry juice

Addition of hydrogen peroxide (H2O2) to blueberry juice changed the red coloration toward brown. Addition of ascorbic acid prevented the formation of brown polymers. An extract of peroxidase (POD) prepared from blueberry fruits was able to oxidize CG into the corresponding o-quinone but only in the presence of H2O2. The chlorogenoquinone plays a dominant role in anthocyanin degradation. We demonstrated that peroxidase extract in the absence of CG showed a weak degradation activity toward blueberry anthocyanins, cyanidin 3-glucoside, and pelargonidin 3-glucoside. Nevertheless, addition of CG increased anthocyanin degradation, leading to formation of brown polymers. Therefore, blueberry POD could participate in the development of browning during blueberry-juice storage.