Changes in flavonoids and nonphenolic pigments during on-tree maturation and postharvest pericarp browning of litchi (Litchi chinensis Sonn.) as shown by HPLC-MSⁿ

• Main Authors: Mareike Reichel, Reinhold Carle, Pittaya Sruamsiri, Sybille Neidhart
• Format: Journal
• Published: 2018
• Subjects: Agricultural and Biological Sciences; Chemistry
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=79955021478&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/49604
• Institution: Chiang Mai University

Polyphenols, chlorophylls, and carotenoids were characterized by HPLC-DAD-MSn in the pericarp of unripe to over-ripe Hong Huey and Chacapat litchi fruit at harvest and during subsequent storage (5 °C, 90% RH, 21 days). (-)-Epicatechin and A-type procyanidins always predominated quantitatively. Besides these ortho-diphenolic compounds, minor novel litchi flavonoids included monohydroxylated structures. Chlorophyll degradation by 73-92% and 7-38-fold anthocyanin accumulation affected pericarp color throughout the last 15-20 days of on-tree maturation. Postharvest, anthocyanins and (-)-epicatechin largely degraded within the first 3 days, accompanied by severe pericarp browning. Without packaging of the fruit, desiccation initially accelerated polyphenol oxidase-induced oxidation of (-)-epicatechin, but then hindered its further progress. Constant levels of the monohydroxylated (epi)afzelechin indicated no involvement of peroxidase. Acting as antioxidants, anthocyanins retarded (-)-epicatechin degradation. Hence, pinkish-red fruit with a molar ratio of cyanidin 3-O-rutinoside to (-)-epicatechin of >3:100 retained flavonoids best. However, brown polymers masked remaining red pigments. © 2011 American Chemical Society.