Unmasking Common Wine Faults: Identifying and Understanding Flawed Wines

You may occasionally encounter a bottle that doesn’t quite taste or smell right. Wine faults can result from a range of issues, including flaws in the winemaking process, improper storage, or contaminated materials. This article will explore some of the most common wine faults, their causes, and how to identify them, helping you to recognize and understand flawed wines.

Cork Taint (TCA)

Cork taint is caused by the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that can develop in natural cork and contaminate the wine. TCA imparts a musty, damp cardboard-like aroma and flavor to the wine, significantly reducing its overall quality and enjoyment.

How to identify: Sniff for musty, moldy, or damp cardboard aromas. On the palate, the wine may taste flat and lifeless, with the fruit flavors being muted or absent altogether.


Oxidation occurs when wine is exposed to excessive amounts of oxygen, either during the winemaking process or due to a faulty closure. Over time, oxidation can cause the wine to lose its freshness, resulting in a dull, lifeless taste and a loss of fruit flavors.

How to identify: Look for browning or deepening of color, especially in white wines. On the nose, the wine may have a nutty, bruised apple, or Sherry-like aroma. The flavors may be flat or stale, with diminished fruit character.

Brettanomyces (Brett)

Brettanomyces, or “Brett,” is a type of yeast that can contaminate wine, producing various off-flavors and aromas. In small amounts, Brett can add complexity to certain wine styles; however, excessive levels can make the wine unpalatable.

How to identify: Aromas of barnyard, horse sweat, or band-aid are common indicators of Brett contamination. The wine may also have a leathery or medicinal taste.

Volatile Acidity (VA)

Volatile acidity is caused by the presence of excessive amounts of acetic acid or ethyl acetate in the wine, often resulting from bacterial contamination or oxidation. VA can impart a sharp, vinegary aroma and flavor to the wine.

How to identify: Sniff for pungent vinegar or nail polish remover-like aromas. The wine may have a sharp, biting taste, with an unpleasantly sour finish.

Sulfur Compounds

Sulfur compounds can form in wine due to various reasons, such as the use of sulfur dioxide (SO2) as a preservative or the natural production of hydrogen sulfide (H2S) during fermentation. While some sulfur compounds can dissipate with time, others may persist and result in off-aromas and flavors.

How to identify: Rotten egg, burnt rubber, or struck match aromas are indicative of sulfur-related faults. The wine may also have a metallic or rubbery taste.

Heat Damage (Maderization)

Heat damage, or maderization, occurs when wine is exposed to excessive heat, such as during transport or storage in a hot environment. Maderization can cause the wine to cook, leading to a loss of freshness and the development of cooked or stewed fruit flavors.

How to identify: Look for a wine with a slightly brownish hue or a pushed-out cork, indicating possible heat exposure. Aromas of cooked or stewed fruit, caramel, or toffee may be present, with the wine tasting dull and lifeless on the palate.

When you encounter a wine with any of these faults, it’s important to remember that not all bottles from the same producer or vintage will necessarily have the same issue. If you suspect a wine is flawed, consider giving the winery or wine shop another chance, as many factors can contribute to wine faults that may not be a reflection of the winemaker’s skill or the wine’s overall quality.

Lastly, if you find yourself with a flawed bottle at a restaurant, don’t hesitate to inform the sommelier or server. They should replace the bottle, as their primary goal is to ensure you have an enjoyable dining experience. By being knowledgeable about wine faults and communicating your concerns, you can help create a better wine culture for all to enjoy.

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Written by

Bernard Marr has a deep passion for wine. He has written hundreds of articles on wine, including features for Forbes, covering wine-making and industry trends. Away from the world of wine, Bernard is a world-renown business and technology futurist. He is the award winning author of over 20 best-selling books and has a combined audience of nearly 4 million people across his social media channels and newsletters.

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