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

J Agric Food Chem. 2011 Apr 27;59(8):3924-39. doi: 10.1021/jf104432r. Epub 2011 Mar 17.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chlorophyll / analysis
  • Chromatography, High Pressure Liquid / methods*
  • Flavonoids / analysis*
  • Litchi / chemistry*
  • Oxidation-Reduction
  • Pigments, Biological / analysis*
  • Tandem Mass Spectrometry / methods*

Substances

  • Flavonoids
  • Pigments, Biological
  • Chlorophyll