07 · Taste Enthusiast

Common wine faults

Most wines are technically sound, but faults do occur. Knowing what they smell like — and whether a wine can be recovered — means you can distinguish a flawed bottle from a style you don't enjoy.

Six faults to know

Cork taint (TCA)

Aroma Damp cardboard, mouldy cellar, wet newspaper

Cause Trichloroanisole (TCA) contamination from the cork, formed when airborne fungi react with chlorine compounds. Can affect the wine at trace levels undetectable to some tasters.

Frequency Estimated 1–3% of corked bottles

What to do Return the bottle. The fault is in the cork — a replacement bottle of the same wine will be fine.

Oxidation

Aroma Flat, stale, bruised apple, sherry-like in white; dried fruit and loss of freshness in red

Cause Excessive oxygen exposure — either through a faulty closure, improper storage or poor winemaking. The wine has essentially started to spoil.

Frequency Common in poorly stored bottles and opened bottles left too long

What to do Discard or use for cooking. Preventable by proper storage and using a wine preserver after opening.

Volatile acidity (VA)

Aroma Vinegar, nail polish remover, sharp acidic bite on the finish

Cause Excessive acetic acid (and ethyl acetate) produced by acetic acid bacteria. At low levels it adds complexity; at high levels it makes wine unpleasant.

Frequency More common in natural wines; occasional in conventional wine

What to do At low levels, accepted in some wine styles (e.g., aged Italian reds, some natural wines). At high levels, a winemaking fault — return if significant.

Reduction

Aroma Struck match, rubber, burnt rubber, rotten egg (hydrogen sulphide)

Cause Sulphur compounds produced during fermentation when yeast is deprived of nutrients. Can develop or dissipate during ageing.

Frequency Common in natural wines; can develop in bottle

What to do Often resolves with aeration — decant the wine or swirl vigorously. If the fault persists after 30 minutes in a decanter, the wine may be beyond recovery.

Refermentation in bottle

Aroma Unexpected fizz, cloudiness, slight yeast character in a wine that should be still

Cause Residual sugar and yeast left in the wine fermented after bottling, producing CO₂. Can occur in wines with poor filtration or stability.

Frequency Uncommon in commercial wine; occasionally in small-production natural wine

What to do Generally a fault — return or discard unless the wine is deliberately pétillant (e.g., Pétillant Naturel).

Heat damage (cooked wine)

Aroma Stewed fruit, jammy, flat and overripe; sometimes the cork is slightly pushed out

Cause Exposure to high temperatures during transport or storage. The wine has essentially been partially cooked inside the bottle, accelerating chemical reactions.

Frequency Risk in poorly stored or transported bottles; particularly at retail

What to do Cannot be undone. If the cork is protruding, the wine has almost certainly been heat-damaged. Return to the retailer.

Preventing faults at home

Most faults encountered at home are caused by poor storage (heat damage, light damage), leaving opened wine too long (oxidation), or the occasional faulty cork (TCA). Storage faults are preventable: see the How to store wine guide for temperature, light and position requirements, and the How long an open bottle lasts guide for how to extend wine after opening.

Cork taint cannot be prevented by the consumer — it is a winery and cork production issue. If you frequently encounter corked bottles from a particular producer, consider that they may have a systematic problem with their closure supplier. Screwcap closures eliminate TCA risk entirely. Diam Closures uses supercritical CO₂ extraction to remove TCA precursors from cork before manufacture, achieving near-zero TCA incidence. Amorim, the world's largest cork producer, publishes TCA quality thresholds for each grade of natural cork. Both represent the industry's most advanced approaches to cork quality.

Sources: WSET (Systematic Approach to Tasting; fault identification curriculum), OIV (oenological standards and permitted practices), AWRI (TCA, VA and fault chemistry research), Diam Closures (TCA-reduction technology), Amorim Cork (natural cork quality control and TCA detection). Last updated: 2026-10-15. Corrections via the contact form.

Questions

About wine faults.

How do I tell the difference between a fault and a wine I just don't like?

A fault has a specific, identifiable cause that makes the wine objectively flawed — the damp cardboard of TCA, the vinegar of volatile acidity, the flat staleness of oxidation. A wine you don't enjoy might simply have a style you find unappealing (high tannin, excessive oak, too sweet) but is technically sound. If in doubt, ask yourself: does this smell like something gone wrong, or does it just taste different from what I expected? The How to taste wine guide covers how to assess wine systematically so you can separate fault from preference.

Can a corked wine be saved?

No. TCA contamination from a faulty cork cannot be removed once it is in the wine. The only fix is a replacement bottle — return the wine to where you bought it. Many retailers accept opened bottles if you explain the fault. Wine by the glass at a restaurant can be returned if corked; the sommelier or server will open a replacement bottle and should verify the fault themselves.

Does a wine being "natural" make it more likely to be faulty?

The absence of added sulphites and minimal filtration in natural wines does increase their vulnerability to certain faults — particularly volatile acidity, reduction and refermentation in bottle. This is a genuine trade-off in natural winemaking. However, well-made natural wines from skilled producers are not faulty — they may have different aromatic profiles (reductive, funky, oxidative) that some drinkers find desirable and others do not. The line between intentional character and fault is contested in the natural wine world. See the natural wine and sulphites article for a deeper look.

Should I send a wine back at a restaurant if it seems faulty?

Yes — if the wine has a clear fault (TCA, significant oxidation, very high volatile acidity), you are entitled to return it. The restaurant will replace it with another bottle of the same wine. Be specific about what you detect: "I think this might be corked — it smells like damp cardboard" is more useful than "I don't like it." If the fault is borderline, ask the sommelier to taste it. If you have ordered an unusual natural wine and it tastes deliberately funky, that is a different conversation.

What does a corked wine smell like and what causes it?

A corked wine smells of damp cardboard, musty cellar, wet newspaper or mouldy cloth — sometimes described as "wet dog." The cause is a compound called TCA (2,4,6-trichloroanisole), formed when naturally occurring fungi in the cork react with traces of chlorine compounds used in sanitisation. TCA suppresses fruity aromas and replaces them with this distinctive mouldy character. Even at concentrations below detection (sub-threshold TCA), it can make a wine taste flat and fruitless without the telltale smell. TCA has no health risk — the wine is unpleasant but not harmful. Estimated to affect 1–3% of all natural cork-sealed bottles. Screwcap and synthetic closures eliminate TCA risk entirely.

Are sulphites in wine harmful?

For the vast majority of people, sulphites in wine are harmless at the levels present in even conventional wines. The European Union, US and most markets require "contains sulphites" on labels once SO₂ exceeds 10 mg/L — which is virtually all wine. True sulphite allergy is rare, affecting roughly 1% of the population, and is more likely to manifest as a skin or digestive reaction than the headaches often attributed to sulphites. Red wine headaches are more plausibly linked to biogenic amines, histamines or simply alcohol and dehydration. Dried fruits (apricots, raisins) contain far higher sulphite levels than wine. Low-sulphite and no-added-sulphite wines are widely available for those who prefer to avoid them.

How do sulphites prevent wine faults?

Sulphur dioxide (SO₂) prevents two of the most common faults: it is an antioxidant (slowing oxidation) and an antimicrobial (preventing acetic acid bacteria that cause volatile acidity). Wines with no added sulphites are more vulnerable to both. This is why natural winemakers compensate with meticulous cellar hygiene, sterile filtration, inert gas blanketing and cool transport. See the natural wine and sulphites article for the full picture.