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
Ripeness in viticulture weight from the juice of a single grape or they can use a hydrometer in the winery with the juice from several dozen or hundreds of grape berries. Different countries around the world use various scales to measure the must weight of grape juice. In the United States, New Zealand, and parts of Australia it is measured in degrees brix (symbol °Bx); in Germany (wine) it is degrees Oechsle (°Oe); in France and most of Europe the Baumé scale was used until 1961 and in Austria the Klosterneuburger Mostwaage (°KMW) scale is used. After "veraison" has begun, viticulturists will test