Volatile Acidity (VA)
Definition - What does Volatile Acidity (VA) mean?
In the context of wine making, volatile acidity is a form of wine spoilage that is byproduct of microbial metabolism that can occur during the wine making process with the introduction of harmful bacteria. Volatile acidity is, specifically, the amount of steam distillable acids in a wine that can be measured through enzymatic testing. The acids commonly measured are lactic, propionic, formic, butyric and acetic acids, when these acids are present in wine in large quantities, the wine is considered spoiled.
WineFrog explains Volatile Acidity (VA)
Testing a wine's volatile acidity is an important part of the wine making process that lets vintners know the likelihood of a wine spoiling. In order to ensure quality wines, there are legal limits of the amount of volatile acidity that wines can contain. Wine grapes contain almost no volatile acidity, however, during the wine making process, harmful yeasts or bacteria can be introduced to the wine and interfere with the process of fermentation and spoil the wine.
Acetic acid is the acid most commonly looked for when measuring volatile acidity and gives the wine a sour vinegar taste. Winemakers can reduce the risk of acetic acid bacteria or other bacteria spoiling wine by eliminating oxygen from wine containers during wine making and by adding sulfur dioxide to keep the harmful bacteria in check. If wine is affected by the acetic acid, winemakers can blend the wine or use reverse osmosis to try to salvage the wine from spoilage.