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Fortunately, nowadays, faulty wine is a rarity. Today’s improved wine production techniques and increased attention to detail regarding bottling and storage have gone a long way towards eliminating the possibility of purchasing a faulty bottle of wine.
Occasionally, however, faults can develop in wine as it matures in the bottle, and you may be unfortunate enough to encounter a rogue bottle. This is, indeed, a disappointing experience.
Common Causes of Faulty Wine
Oxidation
Oxidation occurs when wine has been exposed to too much oxygen in the air. The outcome is loss of flavor and the development of coarseness. The wine tastes and smells foul. Oxidized wines tend to contain higher levels of acetaldehyde.
Maderization
With maderization, the character of the wine changes as a result of the oxidation of alcohol to acetaldehyde. This process produces a slightly almondy flavor that resembles the fortified sweet wine, Madeira (hence the name). The wine taste spoiled. This is often caused by storage in a barrel for too long a period of time. Maderization is accelerated by high temperatures. It may also occur in the bottle. Maderized wine lacks freshness and has a musty taste. (In Madeira, however, it is considered a positive attribute, and the taste is known as “Rancio.”)
Corked Wines
Corked is the term used to describe the unpleasant odor of wine that has been tainted by a defective cork. A cork can be diseased through bacterial action or excessive bottle age. A limited amount of cork taint may just dull the wine but not make it undrinkable. “Corked” is not to be confused with “cork residue,” which is, literally, bits small fragments of cork floating in the wine. Apart from being annoying, the latter is harmless. Also, a wine that sometimes appears corked may merely need to breathe.
Acetification
Acetification occurs when wine is overexposed to air and a microorganism causes a film to develop on the surface of the wine. This film produces acetic acid and the wine becomes sour tasting, resembling vinegary wine. Acetic acid is a volatile acid that is present in all wines and is produced during fermentation. It can turn wine into vinegar if not carefully controlled. Some wine producers consider that small, but detectable quantities of acetic acid are important to the make-up of wine; others believe it is a negative factor.
Foreign Contamination
Contamination can take various forms. For example, it can be caused by powdered or splintered glass caused by faulty bottling equipment or re-used bottles that are tainted by cleaning materials.
Tartrate Crystals
“Tartrate flake” is the crystallization of potassium bitartrate. Although these crystal-like flakes can mar the appearance of white wines, they are perfectly harmless and do not affect the taste of the wine. If wine is stabilized before bottling, this condition is unlikely to occur.
Excess Sulphur Dioxide
Occasionally, a freshly opened bottle of wine has a distinct sulphurous odour. This smell comes from the sulphur dioxide that has been added at the bottling stage to preserve the wine and to keep it healthy. Sulphur dioxide is used in almost every winery throughout the world in order to ensure that the wine is kept absolutely fresh in the bottle. Once the bottle has been opened, any foul smell should disappear within minutes, particularly if you decant the wine to get some air into it.
Hydrogen Sulphide
Wine tainted by hydrogen sulphide smells of rotten eggs. It is irretrievable; throw it away.
Sediment, Dregs, Lees, or Crust
This consists of organic matter given off by wine as it matures, either in the cask or the bottle. Sediment often develops in quality red wines after a few years in the bottle. It can be removed by racking, fining, or, in the case of bottle wine, by decanting.
Secondary Fermentation
Secondary fermentation occurs when traces of sugar and yeast are left in the wine after bottling. The wine develops an unpleasant “prickly” taste that should not be confused with “pétillant” characteristics associated with other styles of healthy, sparkling wines.
Flatness
This term applies to either a sparkling wine that has lost its gas or a still wine that lacks acidity and freshness. It is usually caused by storing the wine for too long.
Cloudiness
Cloudiness is caused by suspended matter in the wine, masking its true color. It may also be caused by extremes in storage temperature.
Spotting Faulty Wine with Your Senses
You can identify faults in the same way you evaluate a wine’s quality and flavor. Use your senses: sight, smell, and taste.
Sight
Look at the color. Wine should always be clear and bright, whatever its color. Cloudiness usually points to bacterial contamination although this is uncommon, nowadays. Don’t confuse cloudiness with sediment that may be present in a quality, aged red wine.
Colors of wines naturally vary according to the type of grape variety used and the climate in which the grapes were grown. However, if a normally fresh, pale wine has a brownish-yellow tinge, the chances are that this wine is faulty. It could be oxidized.
Smell
Smell the wine. If it has a sherry-like smell, beware! Only sherry should smell this way. Again, it could indicate oxidation and maderization. Vinegary or musty, moldy smells are also a warning sign. A smell of rotten eggs is definitely a red alert.
Taste
Use your palate. Your taste buds will confirm what your nose has already told you. Use your senses of taste and smell, in conjunction, when attempting to identify faulty wine.
A Final Tip
If you are in a restaurant, you should still check the wine to see if it is faulty. Take your time and if you have the slightest suspicions, send it back. A good sommelier will always oblige.
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