Often referred to as VA, volatile acidity is a measure of a wine’s gaseous acids. The amount of VA in wine is often considered an indicator of spoilage.
A wide range of acids contributes to a wine’s total VA content, but most winemakers are concerned with acetic acid, which is associated with the smell and taste of vinegar, and ethyl acetate, which causes off-flavors like nail polish or nail polish remover.
Excessive amounts of VA are associated with “unhealthy grapes, poor winery hygiene, oxidative processes or a combination of all of the above,” says Eduardo Soler, winemaker at Ver Sacrum Wines. However, “wine [is] a living thing, and due to its microbiological nature, there is always some degree of VA present in it.”
By law, red and white wine can contain up to 1.4 grams per liter and 1.2 grams per liter (g/L) respectively, yet VA-derived off-flavors are detectable at a much lower threshold, between .6 g/L and .9 g/L.
Detection thresholds may vary from person to person but are also affected by the wine’s style. High sugar content, for instance, can mask VA-derived smells, despite VA being normally present more in sweet wines than in drier styles.
Soler explains that “some wines… made with grapes affected by noble rot…are aged under flor [the layer of dead yeasts that forms on top of sherry] and fermented or aged in an oxidative manner, will have naturally a higher level of VA, which is considered an important part of their heritage and character,” hinting at appellations such as Sauternes, Port, Tokaji and Sherry.
While detection levels might depend on styles and on one’s own sense of smell, what’s an acceptable amount of VA-derived flavors is up for debate.
“VA can be quite divisive,” says Alicia Towns Franken, vice president of the wine portfolio at Archer Roose. “It can be difficult to characterize a subjective fault at times, because whether something is good or bad is in the eyes of the beholder. Personally, a little can be fantastic, but if it’s way out of balance, I find it less enjoyable.”
Towns Franken points out that natural wine enthusiasts seem to show a more welcoming approach to VA, as natural winemaking practices tend to increase the likelihood of high VA levels in wine.
“Being natural winemakers, we do care about hygiene and oxidation, and tend to protect our wines,” says director Michel Drappier. “Sulphur or nitrogen are the most efficient tools against VA… Natural winemakers hate to use these products [which is why] VA tends to be higher in natural wines.
“As long as VA is under control, discreet hints of VA on the nose can add complexity and some freshness,” says Drappier. “But it is a matter of taste.”
Some wine professionals are more dogmatic about what’s an acceptable amount of VA.
“People who argue that it’s a good thing are just bullshitting, trying to cover up a mistake,” says Philip Cox, founder of Cramele Recas, the largest exporter of Romanian wine. Cox’s orange wine was especially designed to appeal to the natural wine market. It contains only .21 g/L of VA, “which is in line with all our other natural, organic and conventional wines,” Cox says.
In small doses, he says, VA can be hard to notice and might not ruin a product in the short term. But “over time it just gets worse and worse, especially if the wine is stored in warm (household) temperatures, and eventually transforms the wine into vinegar,” he says. “That is the reason that I do not consider VA anything but a defect.”