Phenolic content in wine the ellagic and gallic acid found in the wood. In the vineyards, there is also a growing distinction being made between "ripe" and "unripe" tannins present in the grape. This "physiological ripeness", which is roughly determined by tasting the grapes off the vines, is being used along with sugar levels as a determination of when to harvest. The idea is that "riper" tannins will taste softer but still impart some of the texture components found favorable in wine. In winemaking, the amount of the time that the must spends in contact with the grape skins, stems and seeds will influence
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