Wine Word of the Week: Volatile acidity

By Kori ~ July 23rd, 2009.

Wine Word of the WeekThis week’s Wine Word of the Week is volatile acidity.

Official definition from Jancis Robinson’s The Oxford Companion to Wine:
Volatile acidity of a wine is its total concentration of volatile acids, those naturally occurring organic acids that are separable by distillation. Wine’s most common volatile acid by far is acetic acid (more than 96 per cent), which is why it is used as the routine measure of volatile acidity (VA). ….

Acetic acid, in small amounts, is a byproduct of the normal action of yeast in grape juice. However, the major source is the action of a group of bacteria known as acetobacter which require oxygen for their growth and survival, and cause a reaction between the alcohol of a wine and the oxygen to produce acetic acid. Very low concentrations of acetic acid, below 0.2 g/l, do not affect the taste adversely. Increasing concentrations change the taste of the wine, however, from added complexity and fruitiness to a frankly vinegary flavor at levels much above 1.5 g/l.

Layman’s terms from Kori:
Volatile acidity, caused most often by acetic acid, is the result of oxidation during winemaking. Excessive amounts of volatile acidity are considered a wine fault and are characterized by the unpleasant smell of vinegar or nail polish remover.

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