Variation in Antioxidant Metabolites and Enzymes of ‘Red Fuji’ Apple Pulp and Peel During Cold Storage

Abstract

Antioxidants are usually considered with regard to plant defense mechanisms due to the oxidative stress or their importance for human health or both. A comprehensive study in the present research was made to determine the variation in contents of antioxidants and their metabolites (such as ascorbate and glutathione) and enzymes activities of ‘Red Fuji’ apple pulp and peel tissue during cold storage (0 ± 1°C). Results showed that the majority of antioxidant metabolites were maintained in the reduced state, reduced ascorbate and glutathione, mainly localized in apple peel tissue. Strong or very strong correlations between hydrogen peroxide content and superoxide dismutase activity (r = 0.822 and 0.959), reduced/oxidized ascorbate ratio and monodehydroascorbate reductase activity (r = 0.966 and 0.984) as well as reduced/oxidized glutathione ratio and glutathione reductase activity (r = 0.969 and 0.924) were discovered. These results highlight that apple peel tissue could be selected to explore antioxidant mechanism and defense metabolism of apple fruit.