Wine makers have the choice of stainless steel or wooden vats and high or low fermentation temperatures. It is during this first fermentation period that the grape juice must be turned frequently to prevent wild yeast from pickling the liquid, creating a vinegar-like taste. The second fermentation stage malolactic fermentation reduces the acidity of the wine. Bacteria turn the malic acid to lactic acid and is used to various degrees for reds, fortifieds and whites. The third step in wine making is maturation.
Red wines have especially high tannin contents, making the wine undrinkable.
If the wine is allowed to settle, however, the bitterness decreases. The character of the wine is fully influenced during this period. The container used in maturation, the length of the process and the temperature all affect the flavor of the wine. Many reds develop strong characters from long maturation times in newly constructed wooden barrels that impart their flavors into the juice. Reds are known to mature for up to three or four years.