Wine Faults

Wine Faults

By Ben Greene

There is no subject in wine that causes the newcomer more doubt, confusion and worry than that of faults. Is the wine off or do you just not like it? Is it oxidised, corked or simply old? Should you complain? What does ‘corked’ even mean anyway?

When you don’t know what something is supposed to taste like and it seems odd in some way, it’s natural for doubts to surface. Even in the Roberson Wine office disagreements regularly crop up over whether a wine is corked or not, whether it’s supposed to be made in an oxidative style, or whether it’s too old or just right. We also get plenty of wines returned to us as ‘corked’, which upon tasting turn out to be perfectly delicious. To help you decide whether there is anything wrong with your wine, here is a short guide.


‘Corked’ is a greatly misused and misunderstood term but, when applied correctly to wines affected by cork taint, it describes one of the most common wine problems you will encounter. Cork taint is caused by a fungus which can lie hidden deep within cork bark. Its effects can range from the barely detectable to the severe. At the less serious end of the scale, it’s often difficult to say for certain that something is amiss without opening a second bottle for comparison. The fruit flavour of the wine may appear dull and muted, and the wine may finish short. In more severe cases, the wine will smell distinctly musty and, in extreme instances, of rotting cardboard or like a mouldy dog.



While oxidation is part of wine’s natural ageing process, it must happen slowly. If too much oxygen comes into contact with wine, either during winemaking or through the failure of the bottle closure, it will react with it and cause it to spoil. If you’ve ever left wine open for a few days, you will be familiar with the symptoms. It takes on a brown tinge and starts to smell of sherry, and sometimes of rotting apples. If wine is stored in direct sunlight or close to another heat source, it can become ‘cooked’ or ‘maderized’. Heating and cooling causes the liquid to expand and contract, pushing the cork upwards and drawing air into the bottle. The higher temperature also speeds up the oxidation process, and it rapidly becomes undrinkable.



Reduction can be thought of as the opposite of oxidation. Without enough oxygen, wine can develop a highly volatile aroma of rotten eggs. In high concentrations this can spoil the wine permanently, but it is also quite common for certain wines to be a little reductive when you first open them. This is especially true of wine sealed under screwcap, which does not admit any air at all to the bottle, and of wines made naturally, where the lack of any preservatives means everything possible must be done to avoid contact with air and minimise the threat of oxidation. Wines that are a little reductive should be decanted half an hour or more in advance. This will expose them to oxygen and the rotten egg smell will quickly dissipate.



Cork taint, oxidation and reduction are by far the most common wine faults you will encounter. Other problems such as those caused by Brettanomyces (a type of yeast), high volatile acidity or refermentation have mostly been eliminated by modern winemaking techniques. It is enough to know that there can be other problems and, if a wine smells or tastes particularly foul, there’s probably something wrong with it.

Frequently Asked Questions

In the same way that mould is deliberately encouraged in blue cheese, in certain styles of wine some ‘faults’ are considered a virtue. This is particularly true of oxidation. Traditional white Rioja, Tawny Port, Sherry and Madeira are classic examples of deliberately oxidised wines. Many natural wines are either reduced, oxidised or have other traits that more conventional winemakers would consider to be faults. There is also disagreement over whether certain ‘faults’, such as that caused by Brettanomyces, cannot sometimes be desirable. Certain traditional producers consider it integral to the character of their wine, while many more modern winemakers refuse to tolerate it. In general it is worth bearing in mind that a wine can have flaws without being faulty. There is a fine line between eliminating faults and sterilising the life and character out of a wine.

If you are not used to the taste of old wine, it can come as quite a shock when you try something with years or even decades of age behind it. As a result, it is easy to dismiss old wine as faulty when it is not. To avoid getting stuck with something you don’t like, or mistakenly pouring a bottle of great wine down the sink, it’s important to have an idea of what to expect from old wine before committing to it.

Speaking very generally, as wine ages its colour changes (red wines pale and turn tawny, white wines darken) and it loses its primary aromas and flavours of fresh fruit. In place of that fruit you get secondary flavours such as those of stewed fruit, spice, leather, vegetation, earth, meat, game, the farmyard, cheese, and so on. It will not have the same body or the same clean, fresh flavour as when young, but instead it will be more complex, multi-layered, soft and delicate.

It will also be more fragile and susceptible to oxidation once opened. A particularly old and fragile wine should be drunk immediately upon opening before its remaining flavour falls away. Some heroically ancient wines may have a beautiful fragrance and flavour for just a few minutes before the edifice crumbles. If you have the opportunity to taste one, it’s a fleeting but compelling experience not to be missed.

None of this means that the wine is faulty, and neither does a crumbling cork (see below), but there does come a point in the life of every wine when all its fruit has fallen away, it has oxidised and it is simply too old to be enjoyable. For most wines (designed to be drunk within a year) that point comes very quickly, while for the finest wines it may be decades away. It all depends. How mature you like your wine is entirely a personal preference. A wine that is perfect to one person may be past it to somebody else. All you can do is experiment, and make sure you give the wine every opportunity to impress.

No. This is a very common mistake. The outward condition of a cork cannot tell you whether a wine is faulty or not. In particular, it cannot tell you if a wine is corked. A badly damaged cork may have allowed air into the bottle and caused the wine to oxidise, but equally it may not. The only way to be certain is to taste the wine. Old corks in particular can be very damp and very fragile. They can crumble when you insert a corkscrew or slip easily into the bottle. Mould can develop around the outside from storage in a damp cellar. None of these things should be unexpected and they do not indicate a fault in the wine. In fact, damp corks and some mould on the bottle generally indicate that the wine has been well stored. The worst thing that can happen is the opposite, when the cork dries out, shrinks and falls into the bottle, admitting air. For this reason, wine is always stored on its side, with the liquid in contact with the cork.

No. In fact, most of the best wines are bottled unfined and unfiltered and so contain a sediment. The amount of sediment will increase the longer the wine is stored. Old red wine, and especially wines such as Vintage Port, throw a heavy, dark sediment a bit like soil. Old white wines, especially sweet ones, throw a deposit of tartrate crystals, which looks like granulated sugar (but isn’t sweet). These are perfectly natural deposits and not harmful, but neither are they pleasant to drink. If you have a wine that you think might have thrown a sediment, it’s best to pour it into a decanter before serving, leaving the bits behind.

Not usually. Cork taint can happen to any wine, no matter how expensive, sealed with a natural cork. It does not indicate a general problem affecting other bottles of that wine or poor winemaking – it is simply bad luck. If a wine has oxidised due to improper storage, any other bottles stored with it may be similarly affected. In rare instances where a fault has been caused by poor winemaking, a whole batch may indeed be ruined.

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