Effects of different SO₂ dosages on the antioxidation of two kinds of grape during cold storage

Two kinds of grape(Longyan and Hongbaoshi) were treated with normal and excessive SO₂ dosage, and the changes of relative membrane permeability, MDA content and antioxidation in the stems and fleshes were analyzed to determine the effect and mechanism of SO₂ treatment on grape during 0℃ storage. Results show that membrane permeability and MDA content of grapes increase with the increase of SO₂ dosage. The tendency of different enzymes changing in grapes is various. SOD and POD activities show a rise and then a drop, while CAT activity keeps dropping during storage in grapes treated with SO₂. The degree of enzymes activity change in grapes treated by different SO₂ dosage shows a different response. Excessive SO₂ dosage induces more severe change of the enzyme activity. The content of antioxidant(Vc) decreases more quickly in excessive SO₂ package than that by normal SO₂ treatment. Antioxidation systems in Longyan and Hongbaoshi show different responses to SO₂ treatment during storage at 0℃.