The need for white wine aging is limited as compared to red wines, because most white wines are intended for drinking within two to
three years after the vintage date. Many red wines perform well and
even improve with age. Most Cabernet Sauvignon from California will,
with proper storage, continue to improve for ten to fifteen years after
the vintage date. Pinot Noir and Zinfandel wines continues to improve
in the bottle as well, reaching optimum drinkability at up to five to
ten years after the vintage date. Wine aging is an important component that adds to the drinkability of the wine.
It's all about tannins. Tannins are the astringent and bitter group of compounds found in the seeds and skins of grapes. In addition to giving wine an agreeable astringency (that slight "pucker" feeling), tannins impart great aging potential to wine by slowing oxidation.
Tannin extraction is an important part of red winemaking. Unlike the juice of white grapes, which is pressed off the skins prior to fermentation, red wine is fermented with the grape skins, sometimes even with whole grapes still intact. Winemakers monitor the extraction of tannins throughout fermentation by manipulating the skins, which rise to the top and form a cap. The cap will be removed when the wine is determined to have extracted enough tannin. Wine also extracts tannins during maceration ("prolonged skin contact"),which may occur before or after fermentation.