AUTHOR=Wei Dongling , Yang Jiali , Xiang Yue , Meng Lanhuan , Pan Yonggui , Zhang Zhengke 

TITLE=Attenuation of Postharvest Browning in Rambutan Fruit by Melatonin Is Associated With Inhibition of Phenolics Oxidation and Reinforcement of Antioxidative Process

JOURNAL=Frontiers in Nutrition

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.905006

DOI=10.3389/fnut.2022.905006

ISSN=2296-861X

ABSTRACT=Rambutan is a famous tropical fruit with unique flavor and considerable economic value. However, the high vulnerability to postharvest browning leads to a short shelf life of rambutan fruit. Melatonin (MT) is an excellent bioactive molecule that possesses the potential to improve the storability in harvested crops. In this study, the physiological mechanism of exogenous MT in affecting pericarp browning and senescence of postharvest rambutan fruit was investigated. Experimental results showed that application of MT at 0.125 mmol L-1 appreciably retarded the advancements of pericarp browning and color parameters (L*, a* and b*). MT treatment inhibited the increase in membrane relative electrolytes leakage (REL) while lowered the accumulation of reactive oxygen species (ROS) (.O2- and H2O2) and malonaldehyde (MDA). Reduced phenolics oxidation, as indicated by higher contents of total phenolics, flavonoids and anthocyanins accompanying with less activities of peroxidase (POD) and polyphenol oxidase (PPO), was detected in MT fruit compared to control fruit. MT treatment maintained cellular redox state by inducing antioxidant enzymes activity and reinforcing ascorbate-glutathione (AsA-GSH) cycle. Furthermore, the ultrastructural observation revealed that spoilage of cellular and subcellular structures was milder in MT fruit than that in control fruit. The results suggest that MT could ameliorate the browning and senescence of rambutan fruit by inhibiting phenolics oxidation and enhancing antioxidative process.