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
Quinta classification of Port vineyards in the Douro the permitted production level of the vineyard and what price the grower can receive for the wine they produce from the grapes. Quintas are given numerical ratings in several categories – age of the vines, altitude, aspect, vine density, gradient, granite content of the soil, schist content of the soil, types of grape varieties planted, overall location of the vineyard, microclimate, mixture, vineyard soil type, vine productivity, and vineyard maintenance. Vineyards that have favorable attributes in a particular category (such as being planted with an optimal low density of vines) are award points while negative attribute (such as having too