Following alcoholic fermentation by yeast the wine can undergo a second fermentation by lactic acid bacteria. During this so-called malolactic fermentation lactic acid bacteria convert malic acid to lactic acid which results in a lowering of the acidity of a wine. The bacteria also modify some other flavor characteristics of the wine. Wine flavors continue to change while the wine is stored in wooden barrels, stainless steel tanks, and in glass bottles. During this maturation of wine various yeasts and bacteria can be present and further modify wine flavors.
Different wines benefit from longer or only short aging.
The aging potential of a wine is determined by the grape cultivar and vinification practices.