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
Straw wine scale. Grapes should originate in a single wine sub-region and reach at least 6% of alcohol. De Trafford created the first Vin de Paille to be released under the new appellation "Wine from Naturally Dried Grapes" in 1997. They use 100% Chenin blanc. A number of wineries produce straw wine, known in Spanish as "vino de pasas", including Bodegas Oliveros and Bodegas Gonzalez Palacios. Most involve a blend of two grapes, the first one usually a Muscat. Pedro Ximénez grapes are dried in the sun before being vinified, fortified and matured in a solera system like other sherries. Another straw