New phenolic compounds formed by evolution of (+)-catechin and glyoxylic acid in hydroalcoholic solution and their implication in color changes of grape-derived foods.
The reaction between (+)-catechin and glyoxylic acid in model solution system was investigated by LC/DAD and LC/ESI-MS analyses. The formation of phenolic compounds exhibiting absorption maxima near 300 nm and presenting a shoulder around 350 nm was observed. Their structures consisted of a (+)-catechin unit with one or two aldehyde groups linked at positions 6, 8 or 6 and 8 of the A ring. In addition, new yellow pigments exhibiting UV-visible spectra similar to those of xanthylium salts with absorption maxima at 450 and 280 nm were also detected. The major yellow compound was isolated and identified by ESI-MS and 1D and 2D NMR spectroscopy. The implication of these compounds in color change and browning observed during aging of grape-derived beverages is also discussed.
Es-Safi
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ISVV-INRA Institut des Produits de la Vigne, Unité de Recherche Biopolymères et Arômes, 2 place Viala, 34060 Montpellier, France.
Le Guernevé
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Cheynier
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Moutounet
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D000438:Alcohols / Q000737:chemistry; D002392:Catechin / Q000737:chemistry*; D003116:Color; D006038:Glyoxylates / Q000737:chemistry*; D010636:Phenols / Q000138:chemical synthesis*; D019685:Rosales; D012996:Solutions; D014867:Water
D000438:Alcohols; D006038:Glyoxylates; D010636:Phenols; D012996:Solutions; D014867:Water; D002392:Catechin; C031150:glyoxylic acid