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
Wine Grapes viticulture" written by Pierre Viala and Victor Vermorel and published in 1901–1910. Wine Grapes Wine Grapes - A complete guide to 1,368 vine varieties, including their origins and flavours is a reference book about varieties of wine grapes. The book covers all grape varieties that were known to produce commercial quantities of wine at the time of writing, which meant 1,368 of the known 10,000 varieties. It is written by British Masters of Wine Jancis Robinson and Julia Harding in collaboration with Swiss grape geneticist Dr. José Vouillamoz. "Wine Grapes" is not an update of Robinson's earlier book "Vines, Grapes