Proper dosage of sulfur dioxide (100 μl·L -l h 1 ) increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), inhibited the membrane lipid peroxidation, and eliminated the accumulation of malondialdehyde (MDA). The membrane electrical conductivity little more increased than control, the membrane relative permeability basically keeps unchanging. The loss of nutrient compositions, such as organic acid, ascorbic acid and soluble content were reduced, and the grape k...