Of course, wine is aging throughout the winemaking process. Each phase makes a specific contribution to wine characteristics, but the first phase has the greatest influence on wine quality. All of the red color is in the grape skins, and winemakers must leave the juice in contact with the skins for a considerable time to extract the color. Red wine is made by crushing the grapes and then fermenting the juice, the pulp, the skins and the seeds together for several days. Near the end of sugar fermentation, a wine press is used to separate the liquid from the solid materials.
White wine is made by a different process.
First the grapes are crushed and pressed immediately to separate the juice from the solids. After pressing, the skins, stems and seeds are discarded, and the juice is cooled to a low temperature. Then the cold juice is allowed to settle for several hours, and the clear juice is decanted off the residue before it is fermented. White wine is made by fermenting clarified juice. These are the fundamental differences between making quality, red wine and white wine.