How to tell if wine has gone off: 3 faults you can spot before the first sip

Wine that has gone off announces itself through smell and taste long before it poses any risk to health. Ballantynes explains the three main faults—cork taint, oxidation and refermentation—and what each one does to the liquid in your glass. By the end you will recognise the signs, know which bottles to pour away and which merely taste different from what you expected.

Cork taint leaves a damp, musty smell that overpowers everything else

A corked wine carries the compound TCA, which seeps from natural cork when certain moulds and chlorine meet during processing. The result smells of wet cardboard, damp cellar or mouldy newspaper. Even a faint trace flattens the fruit and leaves the wine hollow.

Pour a small measure and swirl it. If the musty note grows stronger rather than fading, the bottle is corked. TCA does not harm you, but it ruins enjoyment. The wine is best discarded, and if you bought it recently most merchants will replace a corked bottle without question.

Oxidation turns wine flat, brown and reminiscent of sherry

Wine oxidises when air reaches it through a failing cork, a crack in the bottle or prolonged exposure after opening. White wines darken to gold or amber; reds lose their brightness and turn brick or brown. The aroma shifts from fresh fruit to bruised apple, caramel or roasted nuts.

Oxidised wine tastes flat because the oxygen has stripped away the lively acidity and fruit. A small degree of oxidation can add complexity to certain aged wines, but when the colour has shifted markedly and the flavour recalls cooking sherry, the bottle has gone too far. It will not make you unwell, yet the character you opened it for has disappeared.

When opened wine starts to fade

Once the cork is pulled, oxidation begins. Light whites and delicate reds lose their edge within a day or two; fuller-bodied wines hold their shape for three to five days if recorked and stored in a cool, dark place. Sparkling wines go flat within hours once the mousse escapes. If yesterday's wine smells dull and tastes tired, oxidation has taken hold.

Refermentation produces fizz, haze and a sharp vinegar note

Refermentation happens when residual sugar and stray yeast meet in the bottle, restarting the process that turned grape juice into wine in the first place. Still wines develop an unexpected sparkle; the liquid may appear hazy or throw a fine sediment. The smell turns sharp and acetic, recalling cider vinegar or nail-polish remover.

This fault signals that the wine was bottled before fermentation finished or that storage conditions allowed yeast to wake again. Refermented wine is safe to drink in small amounts, but the acidity and fizz make it unpleasant. If a still wine hisses when you open it or tastes sour beyond the normal range of acidity, pour it out.

What spoiled wine looks, smells and tastes like in practice

Each fault leaves a signature. Cork taint mutes fruit and imposes a musty, fungal character that does not fade with air. Oxidation dulls colour, flattens aroma and replaces freshness with a tired, nutty or sherry-like quality. Refermentation adds unwanted bubbles, haze and a vinegar sharpness that prickles the nose.

Trust your senses. If the wine smells unpleasant or tastes markedly different from what the grape variety and style suggest, something has gone wrong. A wine that simply does not appeal to your palate is a different matter—personal preference is not the same as a technical fault.

Steps to check a bottle before you pour

1. Inspect the cork and capsule. A pushed-out cork or seepage around the capsule suggests the bottle has been exposed to heat or pressure, raising the chance of oxidation or refermentation.
2. Look at the colour in the glass. Hold it against a white background. Whites should range from pale straw to gold depending on age and grape; reds from ruby to garnet. Brown or amber tones in a young wine signal oxidation.
3. Smell before you taste. Swirl gently and take a moment. Fruit, flowers, spice and earth are welcome. Damp cardboard, vinegar or acetone are not.
4. Take a small sip and let it sit on your tongue. A faulty wine will taste as off as it smells. If the flavour is unpleasantly flat, sour or musty, trust that impression and set the bottle aside.

When a bottle is safe to drink even if it tastes unexpected

Not every surprise signals a fault. Some wines throw harmless sediment as tannins and pigments bind together over time; decanting solves that. Others develop secondary flavours—leather, tobacco, dried fruit—that can seem strange if you expected bright, primary fruit. Natural wines may appear cloudy or smell funky without being spoiled.

If the wine smells clean, tastes balanced and shows no sign of the three main faults described above, it is safe to drink. Whether you enjoy it is another question entirely, and one only you can answer.

The difference between a fault and a style you dislike

A wine you find too tannic, too acidic or too oaked is not faulty—it simply does not suit your preference. Tannin grips the palate and can taste bitter when a red is young; acidity makes the mouth water and can seem sharp in lean wines; oak adds vanilla, toast and sometimes a drying quality. These are deliberate choices by the winemaker. A genuine fault, by contrast, diminishes or distorts the wine in a way no producer intended.

How to store wine so it stays sound

Prevention begins with storage. Keep bottles on their side in a cool, dark place where the temperature stays steady. Heat accelerates oxidation and can push corks out; light degrades delicate aromatics. Avoid storing wine near appliances that generate warmth or in rooms where the temperature swings widely between seasons.

Opened bottles fare better when recorked tightly and refrigerated, even reds. The cold slows oxidation. Bring red wine back to the right temperature before serving by letting it stand at room temperature for half an hour. Serving temperature shapes flavour, but it does not prevent a bottle from spoiling once air has done its work.

Comparison of the three main wine faults

What to do with a bottle that has gone off

Once you have identified a fault, there is little to be done. Corked and oxidised wines cannot be rescued; refermented bottles are unpleasant to drink. If you bought the wine from a shop or received it as part of a delivery, contact the retailer with a description of the fault and, where possible, a photograph of the wine in the glass and the cork. Most merchants replace faulty bottles as a matter of course.

Wine that has merely oxidised after several days open is not the merchant's responsibility, but it need not go to waste. Use it in cooking—stews, sauces and reductions tolerate oxidised wine well, and the alcohol will cook off. Refermented wine, with its vinegar character, can serve as a base for salad dressing if the acidity is not too fierce.

This article is for general information only.

Download PDF: Spotting wine faults: a quick checklist PDF, 28 KB