Ameliorative effect of melatonin against storage chilling injury in pomegranate husk and arils through promoting the antioxidant system

Abstract

Pomegranate is a tropical and subtropical fruit sensitive to chilling injury during its cold storage, leading to quantitative and qualitative losses, as well as reduced economic value. Recently, melatonin has been considered as an environmentally friendly treatment to maintain the postharvest quality of horticultural products. In this study, the effect of melatonin treatment on chilling tolerance, postharvest quality and antioxidant system of pomegranate fruit was investigated during storage at 4 °C for 120 days. According to the results, pH, titratable acidity and the total soluble solids of the fruit were not influenced by applying melatonin. However, melatonin treatment at 100 μM dramatically improved chilling tolerance in the pomegranate fruit by reducing electrolyte leakage and increasing the total phenol content, as well as the antioxidant potential. Melatonin significantly reduced polyphenol oxidase (PPO) activity and increased the activity of phenyl alanine amylase (PAL), catalase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes in the husk and arils of the pomegranate fruit during storage. In addition, melatonin inhibited H2O2 accumulation in the pomegranate fruits. Therefore, our data suggest that melatonin might be useful in improving the postharvest quality and inducing chilling tolerance in pomegranates during the cold storage.