Abstract
Effects of gamma-aminobutyric acid (GABA) (10 and 20 mM), and ascorbic acid (AsA) (2 and 4%) dipping on quality and biochemical changes of 'Hindi- Besennara' mangoes were studied during ripening for 8 days at 20 +/- 2 degrees C and 60-70% RH. Weight loss increased during ripening to 12.5% and was lower in treated fruit than control with lowest value (8.8%) at 2% AsA. Unmarketable fruit percentage (UFP) was lower after 8 days in treated fruit (21.1 to 24.6%) than control (31.9%). Both GABA and AsA treatment retained higher green color, firmness, titratable acidity (TA) and membrane stability index (MSI) but lower total soluble solids (TSS) and TSS/TA ratio during ripening. Total phenol and flavonoid contents in both peel and pulp were higher during ripening than initial, fluctuated and were higher in treated fruit than control. Vitamin C content was higher in treated fruit than control except for 2% AsA. Radical scavenging capacity (RSC) was lower (higher DPPH IC50 values) during ripening in both peel and pulp than initial. RSC of peel showed no changes during ripening but was higher in treated fruit than control. However, RSC of pulp was not affected by treatments but was higher after 8 than 3 and 5 days during ripening. In both peel and pulp, polyphenoloxidase (PPO) activity gradually increased during ripening and was lower in treated fruit than control. While, peroxidase ( POD) activity gradually increased during ripening and was higher in treated fruit than control. Polygalacturonase (PG), xylanase and alpha-amylase activities, in both peel and pulp, showed higher levels than initial, fluctuated during ripening and were lower in treated fruit than control. In conclusion, postharvest dipping in either 10 mM GABA or 2% AsA retard ripening, retained and improved quality of 'Hindi-Besennara' mangoes via inhibiting hydrolytic enzymes and enhancing fruit antioxidant system.