The juice from both red and white wine grapes is without color. In red wine production, the skins are fermented with the crushed juice to give it color and flavor. Unless a full-bodied white wine is desired, the skins and seeds are usually removed from the must after only a few hours leaving juice known as "free run." The skins are pressed to extract all the remaining juice, called "press juice." The free run and press juice are then filtered in preparation for fermentation. At some point in production, the press juice may be blended back into the free-run. Next, the juice is placed in stainless steel tanks or oak barrels where the wine will ferment following the addition of yeast. White wine fermentation lasts from three days to three weeks.
When fermentation has run its course, the vintner will stop the process and filter the wine to remove solids and yeast remnants. The wine is then aged for a period of one week to a year in stainless steel, oak or redwood containers, or it can be aged in the bottle. After aging, the wine may be blended with other wines with different characteristics to create the desired style. The next step is "finishing," a process by which the wine is stabilized and filtered before bottling. Substances such as egg whites or gelatin are added to remove astringent substances or proteins, which can cloud the wine and give off flavors. Sulfites may also be added to prevent oxidation and bacterial spoilage.
How Other Wine Is Made
• Red Wine
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