What causes leather aromas in wine?

Quick answer

Leather aromas in wine come from a combination of aroma compounds, wine development and sensory perception—not one universal “leather compound”.

As wine matures, its aromas can shift from fresh fruit towards more savoury, earthy, dried or animal-like notes. In that context, a taster may describe the wine as leathery. Oak maturation, oxygen exposure, storage conditions and the wine’s underlying composition can influence this development, but leather does not prove that a wine is old, oaked or oxidised.

There is also a fault-related pathway. The yeast Brettanomyces can produce aroma-active compounds associated with leather, barnyard, horse sweat, medicinal and animal-like smells. At high intensity, these characters can overwhelm fruit and make a wine seem unpleasant. At lower levels, tasters may disagree about whether the effect adds complexity or detracts from the wine.

The important point is that “leather” describes what a wine smells like. It does not, by itself, tell you exactly why.

Leather is a sensory comparison

When someone calls a wine leathery, they are comparing its aroma with a familiar reference: worn leather, a saddle, hide or dried animal skin. It is similar to describing a wine as smelling of tobacco, earth or dried herbs. The term helps communicate an impression, but it is not a laboratory result or regulated quality classification.

A leather aroma may sit alongside savoury, earthy, tobacco or dried-meat notes. These descriptions overlap, but they are not interchangeable:

• Earthy suggests soil, forest floor, mushroom or damp earth.
• Savoury is broader, and may suggest herbs, seasoning, umami or meat without an animal smell.
• Tobacco points more towards dried leaf or cigar-box aromas.
• Dried meat suggests cured, roasted or jerky-like character.
• Animal is a wider category that may include hide, fur, meat or sweat.
• Barnyard usually has a stronger stable-like association and is more commonly linked with Brettanomyces.

Australian tasting notes may use “leathery”, “savoury” or “earthy” in these interpretive ways. They are descriptions, not official judgements about a wine’s quality.

How wine development can make leather more noticeable

Leather is often associated with developed wine, particularly when fresh fruit aromas have softened and savoury or earthy elements have become more apparent. This is an association rather than a simple rule: ageing does not manufacture one predictable leather aroma in every bottle.

Time, oxygen exposure, closure performance, storage temperature and the wine’s composition can all affect how aromas evolve. As these factors change the balance of the wine, a taster may notice mature, dried, savoury or leathery character.

That does not mean leather proves a wine is old or has been stored badly. Two wines of the same age can develop very differently, and a young wine may show savoury or animal-like aromas for reasons unrelated to bottle age.

A useful way to think about it is that development changes the relative volume of different aromas. As bright fruit becomes less prominent, other notes may be easier to notice. The leather impression can therefore be part of a wider pattern rather than the result of one specific ageing reaction.

Where Brettanomyces fits

Brettanomyces—often shortened to “Brett”—is a yeast associated with wine spoilage. Its activity can produce several volatile compounds, including volatile phenols, that contribute to aromas described as leathery, smoky, medicinal, sweaty, barnyard or animal-like.

Brett is therefore one credible cause of a leather-like aroma, particularly when the note comes with strong horse, stable, sweat, medicinal or Band-Aid character. But not every leathery wine has Brett. The descriptor alone cannot diagnose Brettanomyces, just as it cannot diagnose oxidation or poor storage.

Brett-related aromas are also concentration-dependent. A restrained note may be noticed differently from a dominant one, and people vary in what they enjoy or reject. However, it is too simplistic to say that a little Brett is always desirable. If the aroma overwhelms fruit or makes the wine feel unbalanced, it is more likely to be regarded as a fault.

What about oak?

Oak can contribute toast, smoke, spice, vanilla and other phenolic or savoury impressions. Barrel environments can also be relevant to microbial activity. These effects may form part of the wider aroma context in which someone perceives leather.

But “leather comes from oak” is not a reliable rule. Leather may be present in a wine with little obvious oak influence, and an oaked wine may smell of vanilla, toast or spice without smelling leathery.

The safest interpretation is that oak may contribute to a wine’s savoury or phenolic background, while development and microbial activity provide other possible pathways.

How to tell complexity from a fault-like note

You cannot make a firm diagnosis from one aroma word, but you can assess the whole wine.

A leathery note may feel like part of a complex, developed profile when it is:

• subtle rather than dominant;
• accompanied by some fruit;
• balanced by freshness, acidity or tannin;
• integrated with savoury, earthy, tobacco or dried-herb aromas; and
• pleasant or at least not distracting.

It is more likely to feel fault-like when it is:

• intense, persistent and unpleasant;
• accompanied by strong barnyard, sweat, medicinal, plastic or stable-like aromas;
• masking the fruit;
• harsh, flat or unbalanced on the palate; or
• the only character you can notice.

These are tasting clues, not laboratory tests. A wine can smell leathery and still be sound, or smell leathery as part of a fault. Context matters.

A simple tasting check

If you notice leather in a glass, pause before deciding whether it is good or bad.

First, smell the wine without swirling, then swirl and smell again. Notice whether the aroma becomes more integrated or more dominant. Next, look for fruit: berries, plums, citrus or other fresh character. Consider whether the wine still feels lively and balanced on the palate.

Ask yourself:

1. Is the leather subtle or overwhelming?
2. Does it sit alongside fruit and savoury complexity?
3. Is there a strong medicinal, sweaty or barnyard smell?
4. Does the palate feel fresh and balanced?
5. Do you actually enjoy the overall wine?

Your answer may differ from another taster’s—and that is normal. Aroma references depend partly on personal experience, so “leather” is a useful description, not a universal quality score.

Frequently asked questions

Does leather mean a wine is old?

No. Leather is often associated with developed wine, but the aroma alone cannot establish a wine’s age. It may reflect several factors, including wine composition, maturation and microbial activity.

Is leather in wine always a fault?

No. A restrained leathery note may be part of a complex savoury profile. A strong, unpleasant character that masks fruit or comes with barnyard and medicinal aromas is more likely to be fault-like.

Does leather mean Brettanomyces?

Not necessarily. Brettanomyces can contribute to leather aromas, but the same descriptor may arise from other combinations of wine development and sensory context.

Is leather caused by oxidation?

Leather should not be treated as an oxidation diagnosis. Oxygen can influence how wine develops, but the descriptor alone cannot identify oxidation.

Is leather caused by oak barrels?

Not always. Oak may contribute savoury, smoky or phenolic impressions, but leather is not an automatic result of oak maturation.