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
Phenolic content in wine increase during ripening so does the concentration of anthocyanins. In most grapes anthocyanins are found only in the outer cell layers of the skin, leaving the grape juice inside virtually colorless. Therefore, to get color pigmentation in the wine, the fermenting must needs to be in contact with the grape skins in order for the anthocyanins to be extracted. Hence, white wine can be made from red wine grapes in the same way that many white sparkling wines are made from the red wine grapes of Pinot noir and Pinot Meunier. The exception to this is the small class of