Activities of antioxidant enzymes during ethanol regulated ripening of tomato fruits

Mature green fruits of tomato of a Desi (local) variety were exposed to ethanol vapour in a closed jar for 24 h. The doses used were 1,2,4, 8 and 10 ml of ethanol per kg of fruit. Antioxidant enzymes like superoxide dis mutase (SOD), catalase (CAT) and peroxidase (POX) activities were determined in treated and untreated fruits till 10th day after the harvest. By this time untreated (control) fruits were red ripe and treated fruits at different stages of ripening depending upon the dose of ethanol. Assay of enzyme activities showed rapid and early rise in superoxide dismutase activity in untreated fruits by 4th day of the harvest coinciding with half ripe stage of the fruits. Adecline in SOD activity was observed later. Lower doses of ethanol i.e. 1 and 2 ml marginally delayed the peak SOD activity but with doses of 4 ml and above, no change in enzyme activity from initial value was noticed till 10th day. Both catalase and peroxidase activities steadily increased as ripening is progressed i.e. till 10th day in untreated and in 1 and 2 ml treated fruits. At higher concentrations of ethanol either no change or slight lower values were noted in the activity of these two enzymes suggesting no change in the condition of fruit from that of mature green stage.