Melatonin treatment enhances bioactive compound retention, antioxidant activity and shelf-life of bell pepper (Capsicum annuum L.) during cold storage

Melatonin (MT), a natural signalling compound derived from tryptophan, has gained significant attention for delaying postharvest ripening and senescence in various fruits and vegetables. In the present study, the effect of MT treatment was evaluated on the postharvest shelf-life of bell pepper. Fruits were dipped in various MT concentrations (70, 120, 170, 220 mu mol L-1) for 20 min and stored at 10 +/- 1 degrees C for 20 days. The bell pepper treated with 120 mu mol L-1 MT significantly suppressed respiration, weight loss and delayed chlorophyll degradation. Additionally, MT (120 mu mol L-1) treatment reduced loss of firmness, titratable acidity and retained total phenol, flavonoid and ascorbic acid content. It hindered malondialdehyde accumulation by enhanced DPPH radical scavenging and antioxidant enzyme activity like superoxide dismutase, catalase and peroxidase, over the control. Conclusively, 120 mu mol L-1 MT prolongs the postharvest shelf-life of bell pepper by 20 days with superior sensory quality, surpassing the control by 10 days. Therefore, MT treatment is a commercially useful technology for maintaining quality and prolonging the postharvest shelf-life of bell pepper.