Quantity and characterization of flavonoids were determined in skins isolated from Vitis vinifera L. cv. Cabernet Sauvignon berries during fruit ripening and at different postveraison water deficits. The per berry amount of anthocyanin, flavonol, and pigment incorporation into proanthocyanidins increased with maturity. The amount of proanthocyanidin extension subunits did not vary with maturity, although the extension subunit composition did. The apparent average degree of polymerization of proanthocyanidins increased with maturity. Incorporation of pigmented material into the proanthocyanidins, together with the apparent increase in average degree of polymerization, suggests that additional terminal subunits, which are not flavan-3-ols, accumulate during fruit ripening. Increased vine water deficit caused small increases in anthocyanins and decreases in flavonols. Red wine flavonoid amounts indicate that postveraison water deficits affect red wine flavonoids primarily by altering berry size and perhaps secondarily by modifying flavonoid biosynthesis.
- Vitis vinifera
- water deficit
- condensed tannin
- pigmented tannin
- red wine
Acknowledgments: The authors gratefully acknowledge Don Williams and the Robert Mondavi Winery for their cooperation in this experiment, and the North Coast Viticultural Research Group and the American Vineyard Foundation for financial support. JAK acknowledges the generous contributions from the Wine Spectator, Knights of the Vine, Mario P. Tribuno, and the Pearl and Albert J. Winkler and Harry Bacigalupi scholarship funds.
- Copyright 2002 by the American Society for Enology and Viticulture