title: Changes in flavonoids and nonphenolic pigments during on-tree maturation and postharvest pericarp browning of litchi (Litchi chinensis Sonn.) as shown by HPLC-MSn.
abstract: Polyphenols, chlorophylls, and carotenoids were characterized by HPLC-DAD-MS(n) 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.
authors.affiliation: Institute of Food Science and Biotechnology, Chair of Plant Foodstuff Technology, Hohenheim University, Stuttgart, Germany.
authors.forename: Mareike
authors.initials: M
authors.lastname: Reichel
authors.forename: Reinhold
authors.initials: R
authors.lastname: Carle
authors.forename: Pittaya
authors.initials: P
authors.lastname: Sruamsiri
authors.forename: Sybille
authors.initials: S
authors.lastname: Neidhart
mesh_terms: D002734:Chlorophyll / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005419:Flavonoids / Q000032:analysis*; D032125:Litchi / Q000737:chemistry*; D010084:Oxidation-Reduction; D010860:Pigments, Biological / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D005419:Flavonoids; D010860:Pigments, Biological; D002734:Chlorophyll