What Is Volatile Acidity in Wine?

Quick answer: is volatile acidity always a fault?

No. Volatile acidity is not automatically a fault.

In wine science, volatile acidity is an analytical measure of volatile, steam-distillable acids. It is dominated by acetic acid, the compound associated with vinegar-like aroma and sharpness. A related compound called ethyl acetate can add aromas similar to nail-polish remover, acetone, glue or solvent.

Small amounts of these compounds can occur naturally during fermentation. They may be barely noticeable, or may contribute a little aromatic lift in some wines. But when volatile acidity becomes strong, persistent or out of balance, it can suppress the wine’s fruit and make it smell vinegary, taste harsh or seem solvent-like. At that point, it is generally considered a wine fault.

The important question is not simply whether VA is present. It is how much there is, how noticeable it is, and whether it suits the wine’s style.

What does volatile acidity smell and taste like?

The most familiar description is vinegar. A wine with noticeable acetic acid may smell sharp, vinegary or pickled, and can taste sour or prickly on the palate.

If ethyl acetate is also present, the aroma may lean towards:

• nail-polish remover;
• acetone;
• glue;
• solvent;
• a pungent, lifted smell that masks the fruit.

These descriptions are useful tasting clues, but they are not a laboratory test. Similar aromas can have different causes, and tasters vary in their sensitivity. A single sniff cannot tell you the wine’s exact chemical composition, concentration or microbial cause.

A practical approach is to pour a small amount into a clean glass, smell it before and after swirling, and notice whether the character remains intrusive. This can help you describe your experience, but only analysis can establish the actual VA concentration.

Acetic acid and ethyl acetate are not the same thing

These two terms are often grouped together in discussions of volatile acidity, but they are chemically different.

Acetic acid is the main contributor to measured VA. It is associated mainly with vinegar-like aroma and sharp, sour flavour.

Ethyl acetate is an ester, not an acid. It can strongly influence how VA is perceived, particularly by adding nail-polish-remover or solvent-like character.

That distinction matters because saying “VA is vinegar” is an oversimplification. VA is a broader analytical category, while acetic acid is its main component and ethyl acetate is a separate compound that can intensify the sensory impression.

How is VA different from normal wine acidity?

Normal wine acidity is often what makes a wine taste fresh, crisp and lively. It contributes sourness, balance and shape to the palate. These acids are commonly described as fixed or non-volatile acidity.

Volatile acidity refers mainly to a different group of volatile acids and is often noticed through aroma as well as taste.

A simple comparison is:

Not every sharp-tasting wine has excessive VA. High ordinary acidity, tannin, carbon dioxide or the wine’s style can also create a brisk or edgy impression.

For more on how wine is made and how fermentation shapes wine, see how wine is made and winemaking.

Why does volatile acidity develop?

Small amounts of acetic acid can be produced by yeast during alcoholic fermentation. Other yeasts and bacteria may also contribute under particular conditions.

One important cause of elevated acetic acid is acetic-acid bacteria. These bacteria use oxygen and can convert alcohol into acetic acid. This means VA can become a risk when wine, juice or grapes are exposed to air while spoilage organisms are present.

Conditions that may contribute include:

• damaged or diseased fruit;
• fermentation stress;
• oxygen exposure;
• poorly sealed tanks, barrels or containers;
• excessive ullage, meaning too much air space;
• warm or poorly protected storage;
• microbial growth during fermentation, maturation or storage.

Oxygen is important, but oxygen exposure alone does not mean a wine will develop high VA. Microorganisms, the condition of the fruit and the wine’s handling all matter.

Brettanomyces and lactic-acid bacteria can also be involved in some circumstances, but VA is not the same thing as Brettanomyces. Brettanomyces is more commonly associated with earthy, leathery, medicinal or smoky characters, although it may contribute acetic acid in certain conditions.

When is VA acceptable, and when is it a fault?

Wine is not chemically blank. A sound wine normally contains small amounts of volatile compounds, including acetic acid. Whether a small amount is acceptable depends on the wine and the person drinking it.

A little volatility may be tolerated when it is integrated with the wine’s fruit, texture and balance. In some wines, it may be experienced as lift or complexity. That does not mean VA is generally desirable, or that more is better.

VA is more likely to be considered a fault when it:

• dominates the aroma;
• clearly smells of vinegar or solvent;
• makes the palate harsh or sour;
• masks the wine’s fruit;
• persists after the wine has been poured and reassessed;
• feels inconsistent with the wine’s intended style.

A delicate, fruit-driven wine may show an intrusive fault at a level that another taster finds interesting in a more robust or unusual style. Sensory thresholds vary with the wine, its sweetness, alcohol, aroma intensity and the individual taster.

What is the Australian legal limit?

Wine Australia identifies a legal maximum of 1.5 grams per litre of volatile acidity, excluding sulphur dioxide and expressed as acetic acid, for Australian wine.

This figure is a regulatory ceiling, not a universal sensory threshold. A wine below that figure is not automatically guaranteed to taste sound, and a drinker cannot determine compliance simply by smelling or tasting a glass. Legal standards, analytical measurements and personal taste are related but not identical questions.

Australian wine drinkers may encounter the term VA in wine-show judging, cellar-door conversations, hospitality training, winemaking courses and tasting notes. It is useful language for describing a wine’s character, but it should not be treated as a diagnosis from one aroma.

How is VA different from other wine faults?

Several wine faults can produce strong or unusual aromas, but they are not interchangeable.

• Oxidation may produce bruised-apple, nutty, stale or browned characters. It can occur alongside VA, but it is a separate process.
• Reduction is associated with sulphur compounds and may smell like struck match, rubber, rotten egg or cabbage.
• Cork taint is commonly associated with musty, damp-cardboard or mouldy aromas.
• Brettanomyces may produce leathery, farmyard, medicinal or smoky characters. It is not another name for VA.
• Sulphur dioxide can smell sharp or match-like in some conditions, but it is not volatile acidity.

Wine faults can overlap, and sensory descriptors are not proof of one particular compound. The most useful response is to describe what you notice without claiming more certainty than the glass allows.

Frequently asked questions

Is volatile acidity the same as vinegar?

Not exactly. Acetic acid, the main component of VA, is associated with vinegar. But VA is a broader analytical measure, and ethyl acetate may add solvent-like aromas.

Can decanting fix volatile acidity?

Do not rely on decanting to remove established VA. Opening a wine may change how its aromas are perceived, but aeration does not reliably remove acetic acid or ethyl acetate and may expose the wine to more oxygen.

Does volatile acidity mean a wine is unsafe?

The useful wine question is usually about quality and balance, not diagnosis from aroma. A vinegar or solvent smell may indicate a sensory problem, but it does not establish the wine’s safety, legality or exact cause.

How should I describe a wine that seems high in VA?

You might say that it smells vinegary, sharp or solvent-like, and that the aroma dominates the fruit. That is more accurate than claiming to know the exact concentration or microorganism responsible.