Phenolic content in wine - quercetin. Like other flavonoids, the concentration of flavonols in the grape berries increases as they are exposed to sunlight. Some viticulturalists will use measurement of flavonols such as quercetin as an indication of a vineyard's sun exposure and the effectiveness of canopy management techniques. Anthocyanins are phenolic compounds found throughout the plant kingdom, being frequently responsible for the blue to red colors found in flowers, fruits and leaves. In wine grapes, they develop during the stage of "veraison" when the skin of red wine grapes changes color from green to red to black. As the sugars in the grape
Classification of wine defined names reflecting the traditional wines produced in the named region. These naming conventions or "appellations" (as they are known in France) dictate not only where the grapes in a wine were grown but also which grapes went into the wine and how they were vinified. The appellation system is strongest in the European Union, but a related system, the American Viticultural Area, restricts the use of certain regional labels in America, such as Napa Valley, Santa Barbara and Willamette Valley. The AVA designations do not restrict the type of grape used. In most of the world, wine labeled Champagne