Melatonin treatment maintains the quality properties and storability of carambola fruit by modulating energy metabolism.

The influences of 150 μmol/L melatonin treatment on the quality properties, storability, and energy metabolism in carambola fruit were explored. The results showed that, compared to the control, melatonin treatment significantly retained higher rate of commercially acceptable fruit, and retarded the development of fruit browning and yellowing. Additionally, melatonin treatment displayed higher levels of chromaticity L and h values, titratable acid, total soluble solids, total soluble sugars, sucrose, and vitamin C, but lower respiration rate, chromaticity a and b values, and reducing sugar content. Moreover, melatonin treatment presented higher levels of ATP, ADP, and energy charge, as well as higher activities of H-ATPase, Mg-ATPase, and Ca-ATPase in the membranes of vacuole, mitochondria, and plasma, thereby reducing the damage to cell membranes. These results will provide a scientific basis and practical guidance for melatonin to maintain the quality properties and storability, and to prolong the shelf life of postharvest carambola fruit.