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
History of the wine press would subject the grapes/pomace to increasing pressure from one end of the press to the other with new grapes being added and the pomace being continuously removed. Another advancement in the horizontal batch press was the complete enclosure of the press (sometimes called "tank press") that reduced the exposure of the grape must to air. Some advance presses can even be flushed with nitrogen to create a complete anaerobic environment that can be desired for wine making with white wine grapes. Additionally, many of today's modern presses are computerized which allows the operator to control exactly how much pressure is