White wines are always fermented in closed containers sealed with a fermentation trap. All fermentations should be monitored by measuring the Brix each day. When fermentation is complete, the new wine should be racked into a clean container, and 50 milligrams per liter of SO2 should be added. Red Fermentations Red grapes have colorless juice. The color is in the grape skins.
Red wine is made by fermenting the juice, pulp, seeds and skins together for several days.
Lengthy skin contact does not increase color, but it does increase wine astringency. Short skin contact time produces softer, more fruity red wines. Skin contact time is always a compromise, and winemaking experience is needed. Usually, four to seven days is adequate for red fermentations. A cap of skins will begin to float after fermentation starts.