Storage

Sulfites Sulfur-containing compounds called sulfites are naturally found on grapes to retard the growth of bacteria and mildew. Most winemakers add sulfites to the wine to help stabilize it as it ages. However, some people are allergic to sulfites -- wines that are labelled as sulfite-free have had the sulfites chemically removed.

Once the fermentation process is completed, red wines are sent to the press to separate the skins from the wine. The red wines are then filtered to remove the yeast. White wines are allowed to settle and are filtered to remove the yeast. Once the yeasts are removed, the wines are stored in either stainless steel storage tanks or oak barrels (oak gives many wines a characteristic flavor) depending on the type of wine. In some red wines, a second type of fermentation, called malolactic fermentation, is undertaken while in storage. In malolactic fermentation, the winemaker adds a bacteria to the wine that breaks down malic acid, a byproduct of aerobic (oxygen-requiring) metabolism, into lactic acid, a byproduct of anaerobic (no oxygen) metabolism. Lactic acid is a milder acid than malic acid. The aging process can be anywhere from three months to three years.

Photo courtesy Chatham Hill Winery Wine is stored in oak barrels or stainless steel storage tanks.