Postharvest chitosan, trans-resveratrol and glycine betaine dipping affect quality, antioxidant compounds, free radical scavenging capacity and enzymes activities of 'Sukkari' bananas during shelf life

Effects of chitosan (0.5 and 1%), trans-resveratrol (1.6 × 10−5 M, 1.6 × 10−4 M and 1.6 × 10−3 M) and glycine betaine (GB) (10, 15 and 20 mM) dipping on quality and biochemical changes of 'Sukkari' bananas were studied during ripening at shelf life (SL) conditions for 13 days. Weight loss increased during shelf life but was not affected by treatments. Peel color index increased during SL and was lower at both resveratrol and GB treatments than control. Membrane stability index (MSI) of peel decreased during SL and was higher, especially after 6 days, at resveratrol and GB treatments than control. Firmness decreased during SL and was higher, especially after 6 days, at resveratrol and low and moderate rates of GB than control. TSS increased during SL and was lower at all treatments than control. Acidity concentration decreased during SL and was higher, especially after 6 days, at low rate of chitosan, resveratrol and high rate of GB than control. pH increased during SL and was higher at low rate of GB and lower at low and moderate rates of resveratrol than control. Vitamin C concentration decreased during SL but was not affected by treatments. Total phenols concentration decreased during SL and was higher at GB and moderate rate of resveratrol than control. Total flavonoids concentration decreased during SL and was lower at resveratrol and low and high rates of GB than control. FRSC (DPPH IC50) increased during SL and was lower at GB and low and moderate rates of resveratrol than other treatments, especially after 6 days. The relations of such biochemical changes with α-amylase, xylanase, polygalacturonase, peroxidase and polyphenoloxidase activities were discussed. In conclusion, both postharvest trans-resveratrol and GB treatments retained quality of 'Sukkari' bananas during SL and being suggested as natural alternatives to synthetic chemicals.