Pressing (wine) red wine production the timing of when to press is one of the most important decisions in the wine making process since that will be the moment that maceration and phenolic extraction ceases. Some winemakers use the decreasing sugar level (such as brix measurement) scale and press once the wine has reached complete dryness. Often winemakers will use taste to determine if the wine has extracted enough tannins to produce a balanced wine and may press before complete dryness (such as at 3-8 brix). Though removing the skins by pressing often removes some solids that the wine yeast need to
Phenolic content in wine concentration in the skins of wine grapes. The accumulation in ripe berries of different concentrations of both bound and free resveratrols depends on the maturity level and is highly variable according to the genotype. Both red and white wine grape varieties contain resveratrol, but more frequent skin contact and maceration leads to red wines normally having ten times more resveratrol than white wines. Resveratrol produced by grape vines provides defense against microbes, and production can be further artificially stimulated by ultraviolet radiation. Grapevines in cool, damp regions with higher risk of grape diseases, such as Bordeaux and Burgundy, tend to