Fruit tissue (4 g) was ground in a cold mortar and pestle with 4 ml potassium-phosphate buffer (0.1 mol L
1
, pH 7.3) containing 1 mmol L
1
EDTA and 2 mmol L
1
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. AsA-POD activity was measured according to the method of Amako, Chen, and Asada (1994). The reaction was started via adding H
2
O
. The G-POD enzyme assay mixture containing 0.1 mol L
1
2
phosphate buffer (pH 6.1), 4 mmol L
1
guaiacol as donor, 3 mmol L
1
H
2
O
as substrate and 1.0 ml crude enzyme extract. The total reaction volume was 3.0 ml. The rate of change in absorbance at 420 nm was measured, and the level of enzyme activity was expressed as the difference in absorbance (OD).