Acetic Acid
Acetic acid is the main volatile acid found in wine. Although most people do not recognize the name and structure of this acid, its vinegar-like smell is unmistakable.
The Role of Acetic Acid in Wine
As one of the most chemically simplistic acid in wine, acetic acid can be either beneficial or detrimental based on its concentration. Its presence in wine is mainly due to yeast and bacterial metabolism. But it is also formed as wine ages in oak cooperage.
The normal level of acetic acid in wine is around 300mg/liter. This number may not mean much to you, but it is very important to winemakers. Around this level, acetic acid is very desirable, contributing to the wines smell and taste. Another positive benefit of acetic acid is through its reaction with esters, producing acetate esters, which contributes to a wines fruit character.
It is critical, however, to keep the acetic acid concentration around 300mg/liter. As it increases above this critical number, it gradually gives the wine a sour taste, and the perception of vinegar becomes more apparent. This can ruin a perfectly good wine.
A high concentration of acetic acid in wine is a strong indication that the grapes have been contaminated. The culprit of contamination is usually acetic acid or lactic acid bacteria. Winemakers and viticulturalists will pay the utmost attention to make sure that this does not occur.
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