Volatile Acidity (VA) in Wine: Lift, Kombucha or Vinegar?
Volatile acidity is the tangy, kombucha-like edge in many natural wines. What VA is, the legal limits in the US and EU, how it tastes at different levels, why natural wine often has more, and when it becomes a fault.
If a natural wine has a tang that reminds you of kombucha, cider vinegar or balsamic, that's volatile acidity, or VA. A little is one of natural wine's signatures. A lot is vinegar in progress.
What VA is
Wine contains several acids. Most (tartaric, malic, lactic, citric) stay put in the liquid. Volatile acids evaporate easily, so you smell them. In wine, volatile acidity is almost entirely acetic acid, the acid in vinegar (Penn State Extension has a clear technical overview).
VA usually travels with ethyl acetate, an ester formed from acetic acid and alcohol, which smells like nail-polish remover or solvent. When people say a wine "has VA", they often mean the combined effect of both.
“Oxygen, warmth, low sulfur dioxide and higher pH all help VA rise.”
Where it comes from
- Acetic acid bacteria (Acetobacter and relatives), which need oxygen and turn alcohol into acetic acid. This is how vinegar is made.
- Yeasts during fermentation, especially some wild yeasts and stressed fermentations.
- Lactic acid bacteria, which can produce some acetic acid too.
Oxygen, warmth, low sulfur dioxide and higher pH all help VA rise.
What it tastes like at different levels
- Low: you won't name it, but the wine feels lifted and bright. Many wines, natural or not, sit here.
- Noticeable: kombucha, cider vinegar, a raspberry-vinegar edge on red fruit. Plenty of natural-wine drinkers enjoy this; plenty don't.
- High: sharp vinegar on the nose, nail polish, a hot, scratchy finish. Most people call this a fault.
Where the line sits depends on the wine. A dense, ripe red can carry more VA before it shows than a light white. Thresholds also differ between people; the Winemakers Research Exchange summarises what's known.
The legal limits
Unlike most natural-wine words, VA has hard legal ceilings:
- United States: a maximum of 0.14 g per 100 mL for red table wine and 0.12 g per 100 mL for other grape wine, expressed as acetic acid, with higher limits for wines from very ripe, unameliorated juice (27 CFR 4.21).
- European Union: maximum VA levels are set in EU wine law by wine type, with some derogations for specific wines (Delegated Regulation (EU) 2019/934).
A wine that's over the limit can't legally be sold as wine in that market. Natural or not, it's the same rule. Most VA you'll taste in a natural-wine bar is well under it; the limit is far above where most people start to notice.
Why natural wine often has more
The conventional cellar's main defence against acetic acid bacteria is sulfur dioxide, along with careful oxygen management and, sometimes, filtration. Natural winemaking uses little or no SO2. Spontaneous fermentations with native yeasts can also start slowly, leaving a window for VA to develop.
Some natural winemakers accept a little VA as part of a wine's energy. Others work hard to keep it down. That's a style choice, and it's why two natural wines from the same region can feel completely different.
How winemakers keep VA down
Without much sulfur, prevention is the main tool:
- Healthy fruit. Damaged or rotten grapes arrive already carrying acetic acid bacteria. Careful sorting matters more when there's no SO2 to fall back on.
- A clean, quick start to fermentation. Some natural producers use a pied de cuve, a small batch of juice fermented a few days early with native yeast, to get the main fermentation going fast.
- Keeping air out. Topping up barrels and tanks so there's no headspace, and handling the wine gently at racking and bottling.
- Cool temperatures in the cellar and in transport.
Character or fault?
The question we ask of all funk: does it add something, or replace everything? A VA lift that makes a light red taste fresher and more drinkable is doing a job. A VA that makes you think of salad dressing before fruit has taken over. Is funky wine flawed?
Practical tips
- Chill it a little. Lower temperature mutes volatile aromas. Light, high-VA reds often work better cool. Should natural wine be chilled?
- Don't leave it open warm. An open bottle exposed to air at room temperature is a good home for acetic acid bacteria. Recork and refrigerate. How long natural wine lasts
- At a bar, "something bright but not too volatile" is a perfectly normal request.
Related reading
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