Fruit tissue (4 g) was ground in a cold mortar and pestle with 4 ml potassium-phosphate buffer (0.1 mol L, pH 7.3) containing 1 mmol L1EDTA and 2 mmol L1 DTT. The homogenate was centrifuged at 12,000 g for 10 min at 4 C. The supernatant was used for the AsA-POD, and G-POD assays.