Melatonin enhances the synthesis of volatile esters and lactones in apricot during low temperature storage

Low temperature storage often leads to chilling injury in apricots, causing a loss of aroma and a decrease in its commodity value. In this study, melatonin (MT, 0.1, 0.2, and 0.4 mmol L−1) dipping treatment was used to improve the aroma quality of apricot ('Jintaiyang' and 'Pingdingxiang') at low temperature (4 °C). Results demonstrated that the application of 0.2 mmol L−1 MT treatment effectively maintained firmness and soluble solids content (SSC), and inhibit the ethylene production and respiration rate of apricots. Additional observations revealed that MT was capable of inhibiting the activities of LOX (lipoxygenase), HPL (hydroperoxidelyase), and ADH (alcohol dehydrogenase) enzymes, thereby reducing the levels of alcohols and aldehydes in apricots. Conversely, MT upregulated the activities of LOX, HPL, ADH, ACX (acyl-CoA oxidase) and AAT (alcohol acyltransfera) enzymes, promoting the biosynthesis of lactones and esters in apricots. Thus, melatonin might be an effective method for low temperature storage of apricot by promoting the recovery of aroma substances.