Is your wine flawless, or flawed? Is what you taste an intentional style, or an accident of storage? The degree to which wine faults are considered problematic often lies in the nose (or palate) of the beholder, and it’s often hard to tell the difference.

Here’s a guide to seven common wine faults, plus two situations you can happily ignore.

1.  Corked Wine

Warning Signs

Sniff for dusty aromas of wet newspaper and damp basement, and dull, muted fruit.

Cause

TCA stands for 2,4,6-trichloroanisole, and it’s the chemical culprit behind “corked” wine. It frequently derives from natural cork closures. TCA develops when the plant phenols from cork-tree bark are exposed to chlorine, a common sterilizer. Tasters may mistake mustiness for the forest-floor and mushroom notes called sous bois by the French, or confuse it for oxidation or other out-of-condition problems. The rate of cork taint hovers around 3 percent globally, but many wine industry professionals argue it gets blamed far more frequently.

Fault Line: Critical

While cork taint isn’t physically harmful to drinkers, it can easily render a wine undrinkable.

2. Over-the-Hill (versus Mature)

Warning Signs

Look for faded color, loss of personality, structure and freshness.

Cause

It is common to store an expensive or special bottle for a future occasion. But if you save that treasure too long, it can extend past its optimal sipping point. Most wines aren’t built to age more than a few years, and even those that can will have ageability differences due to storage conditions. However, an appreciation for a bottle’s later life can also be subjective. As an example, aged Bordeaux will soften and synergize. Its color will fade from ruby to garnet, and the wine will swap primary fruit for tertiary flavor notes of tobacco and cedar. Many wine collectors pay a lot of money for that.

Fault Line: Subjective

A bottle may be past its prime to one wine lover, but characterful to another. Let your taste buds guide you

3. Oxidation

Warning Signs

Look for ruddy, brownish whites that may smell of Sherry or cider, or brick-orange reds that seem flat and lifeless.

Cause

Oxidation is a common consumer complaint. It can begin during winemaking, storage or within hours of opening the bottle. Always ask your bartender which day he or she opened that by-the-glass pour. Packaging may also be the cause. Boxed wines have shorter shelf lives than bottles due to the high rate of oxygen exchange in the boxed bags. If a bottled wine is fresh off the shelf and still tastes oxidized, the problem probably started with the producer. In the case of Sherry, vin jaune and some white wines, those nutty flavors are deliberate.

Fault Line: Moderate

Oxidation presents itself in degrees of intensity, but if color, aroma and flavor loss are severe, consider making vinegar.

4. Cooked/Maderized

Warning Signs

Taste for roasted, stewed or jammy reds with prune or raisin flavors, or whites that are brown, nutty and Sherry-like, and not in a tasty way.

Cause

Prolonged exposure to heat or a series of temperature spikes can cook a wine. Also known as maderization, for the process used to make Madeira, few wines can tolerate the treatment. Cooked wines typically show signs of oxidation, too. A cork partially dislodged from the neck is a good indicator that heat has expanded the air inside. This can happen anywhere: a hot dock during shipping, a sunny window in a store, a pizza restaurant that stores Chianti above the oven, or a car trunk in the summertime.

Fault Line: Severe

If a wine has been cooked enough to notice, use it as braising liquid instead.

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No Cause for Concern 

Though often mistaken for wine faults, these common phenomenon are perfectly normal, and won’t harm the flavor of your wine.

Wine Diamonds

Sign  

Crystals in the bottom of the bottle.

Cause 

No, that’s not glass in your glass. Rather, it’s a tartrate deposit. If you’ve ever used cream of tartar in a cake recipe, you’ve baked with the same material as those jagged crystals on the bottom of your bottle or cork. They form when naturally occurring potassium and tartaric acid combine and sink out of the liquid. While winery techniques mostly prevent it from happening, they’re harmless.

Sediment

Sign  

Dark, grainy material in the bottom or side of your red wine bottle.

Cause 

 Only in the wine world would dregs in your bottle be a good thing. Often the mark of quality, like with vintage Port, sediment occurs for two reasons. First, many producers don’t filter or fine their wines, in order to preserve flavor and texture. This leaves behind particles that settle with time. The second reason relates to aging. Research indicates a combination of acid, tannin and color compounds bond and fall out. Fortunately, sediment is innocuous. Just decant before serving.

5.  Brettanomyces or “Brett”

Warning Signs

“Barnyard,” “horsey” and “feral” are typical aroma descriptors.

Cause

More than any other “fault,” Brettanomyces, shortened to Brett, polarizes the wine industry. Brett has long played a pivotal role in the flavor profiles associated with prestigious appellations and grapes, notably France’s Southern Rhône Valley. Before anyone knew what caused aromas of “farmyard,” “bandage” and “horse blanket,” famous producers infected with this spoilage yeast won accolades and high scores from critics. Château de Beaucastel from Châteauneuf-du-Pape routinely crops up as an example. Yet, despite its historical relevance, most wineries try to avoid Brettanomyces yeast in their wines.

Fault line: Moderate

A beautiful funky note to one taster may smell beastly to another. While it’s a matter of preference, too much Brett can overwhelm a wine.

6.  Volatile Acidity, also known as VA

Warning Signs

Smells ranging from a whiff of acetone or nail polish, to downright vinegar.

Cause

All wine has volatile acidity. Its presence only becomes problematic at higher, detectable levels. This typically occurs after the bacteria that produces it runs wild in the winery. Those gremlins, known as acetobacter, can turn wine into vinegar. Combined with alcohol and oxygen, they can tip VA into unpleasantness. Some winemakers use it as a tool to bring complexity or “high-toned” notes to their wines. But once aromas have moved into vinegar territory, the wine has, well, soured. Ultimately, it’s rare to encounter a commercial wine rendered faulty from VA. The best place to fine one: a county-fair wine competition.

Fault line: Moderate

Determined case-by-case. At lower levels, VA adds complexity. At high levels, it ruins a wine’s fruit flavors.

7.  Reduction

Warning Signs

From struck match to garlic, rubber and rotten eggs.

Cause

Reduction is the opposite of oxidation. It occurs during the winemaking process, when a wine’s limited exposure to air leads to volatile sulfur compounds. When used by the winemaker to preserve fresh fruit aromas or add complexity, you might notice a struck match or smoky, gunflint aroma after opening the bottle. At higher levels, odors of garlic or rotten eggs take hold. But a little reduction can “blow off,” as wine pros say, through aeration.

Fault line: Mild

It’s highly unusual to get a whiff of rotten egg from a commercial winery. For milder forms, just decant for an hour or toss in a clean copper penny.

Sourced: Mowery L. (2018)  Wine Faults & How to Recognise Them. Available :tiny.cc/1l5vqy (accessed Feb 5, 2018)