Identification and Changes of Flavonoids in Merlot and Cabernet Sauvignon Wines

Twenty components of an ethyl acetate extract from Merlot and Cabernet Sauvignon wines were isolated by recycle preparative HPLC. A combination of paper chromatography, fluorescence behavior, gas chromatography, reaction with molybdate, reaction with vanillin/HCI, ultraviolet spectrometry and mass spectrometry was used to gain information about the identities of the isolated compounds. Seven of the isolated compounds were catechins, procyanidins or degradation products thereof. Three flavonol glycosides were isolated and one was characterized as an isorhamnetin‐3‐glycoside. Four compounds were isolated with identical molecular weights and an uncharacteristic blue reaction with vanillin/HCl. These components were interconvertable and thought to be cis‐trans isomers of flavenes. The changes in these components during aging of Merlot and Cabernet Sauvignon wines are discussed.