EVALUATION OF OXIDATIVE STRESS AND ANTIOXIDATIVE SYSTEM IN BER (ZIZIPHUS MAURITIANA L.) FRUITS DURING STORAGE

ABSTRACT Lipid peroxidation, oxidative stress and antioxidative system were monitored during storage of Ber fruits cv Umran (shelf life; 8–9 days) and Kaithali (shelf life; 4–5 days). Mature green fruits stored under ambient conditions were analyzed at a 2-day interval until complete deterioration. Throughout storage, lipoxygenase activity, malondialdehyde and hydrogen peroxide content were higher in Kaithali than in Umran and increased continuously in both the varieties. Activities of superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase decreased continuously whereas that of peroxidase increased up to 4th day of storage and thereafter decreased. Umran showed higher activities of superoxide dismutase, peroxidase, ascorbate peroxidase and glutathione reductase at almost all the stages of storage. The catalase activity, however, was higher in fresh Kaithali fruits and thereafter differences among the varieties were insignificant. Ascorbic acid increased up to the 8th day of storage and then decreased sharply. Glutathione and β-carotene exhibited a continuous decline whereas α-tocopherol first increased up to 4 days and then declined in both the varieties throughout storage. PRACTICAL APPLICATIONS Ber (Ziziphus mauritiana) is an important fruit crop of India and has become popular because of its high nutritional value and low cost. However, because of short shelf life, it cannot be stored for longer and hence accounts for a great economic loss. The results have shown that storage of Ber is accompanied by a progressive increase in oxidative stress. The cultivar with shorter shelf life had higher oxidative stress than the one with longer shelf life. Increased production of reactive oxygen species (ROS) during storage eventually induced antioxidative system including enzymes and metabolites. The variety with longer shelf life had higher potential of combating ROS because it had consistently higher activities/levels of antioxidant enzymes and metabolites throughout storage. The results could be exploited in the on-going research program aimed at increasing the shelf life of fruits.