Postharvest melatonin treatments reduce chilling injury incidence in the 'Angeleno' plum by enhancing the enzymatic antioxidant system and endogenous melatonin accumulation

•Postharvest melatonin application increases the shelf-life of 'Angeleno' plums.•0.5 mmol L−1 melatonin treatment reduces the incidence of chilling injury.•Exogenous melatonin enhances ascorbate peroxidase activity.•Postharvest melatonin treatments enhance its endogenous content.•Melatonin treatments delay anthocyanin synthesis. Consumers particularly value plums for their high levels of nutrients and bioactive compounds. Cold storage is the primary method to extend shelf-life, but it can cause physiological disorders, such as chilling injury and decreased fruit quality. Melatonin is an eco-friendly tool that reduces quality loss and chilling injury in fruit and vegetables. 'Angeleno' plums were treated with different concentrations of melatonin (0, 0.1, 0.3 and 0.5 mmol/L), stored at controlled low temperature and humidity for 60 d, and subsequently stored at 20 °C for 5 d. Quality parameters (respiration rate, ethylene production, weight loss, total soluble solids, titratable acidity, colour, firmness, sucrose, glucose, fructose and sorbitol), chilling injury incidence, malondialdehyde, bioactive compounds (melatonin, total phenols, anthocyanins and total antioxidant activity) and antioxidant enzymes (peroxidase, catalase and ascorbate peroxidase) were analysed. The postharvest application of melatonin positively affected the quality attributes of 'Angeleno' plums, including reduced chilling injury and improved the fruit's non-enzymatic and enzymatic antioxidant systems. Therefore, melatonin could be a valuable tool for maintaining fruit quality and reducing losses in the plum industry.