Physicochemical Studies of New Anthocyano-Ellagitannin Hybrid Pigments: About the Origin of the Influence of Oak C-Glycosidic Ellagitannins on Wine Color

Kinetic and thermodynamic UV/Vis and structural NMR spectroscopic investigations on the anthocyano‐ellagitannin hybrid 1‐deoxyvescalagin‐(1β→8)‐oenin revealed that its enhanced color stability relative to that of the red‐colored pigment oenin and resulting bathochromism can be rationalized in terms of an intramolecular π‐stacking between the grape‐derived oenin chromophore and the oak‐derived vescalagin 4,6‐hexahydroxydiphenoyl moiety. The results led us to suggest that this bathochromism‐inducing molecular association could be the first ellagitannin‐based molecular‐level explanation of the red‐to‐purple color change that takes place during the aging of wine in oak barrels. Purple‐colored anthocyano‐ellagitannins, derived from the oak ellagitannin vescalagin and the red‐colored grape pigmentsoenin and malvidin, are likely to play a role in the modulation of wine color during aging in oak barrels.