Using cork as a wine bottle closure allows a small amount of air to interact with the wine, which helps high-quality wines age gracefully. However, it also introduces the risk of cork taint. Cork taint is one of the most common wine faults; affected wines often smell musty, moldy, or reminiscent of damp cardboard and wet newspaper. So how does cork taint occur? And can a tainted wine still be consumed?
1. What Is Cork Taint?
As the name suggests, cork taint refers to wine being contaminated by its cork closure. The primary culprit behind this fault is a chemical compound called TCA, short for 2,4,6-Trichloroanisole. Another related compound, TBA (2,4,6-Tribromoanisole), can cause similar defects, though it is less common and generally less severe than TCA.
How does TCA form? It is the result of an interaction between phenolic compounds, chlorine compounds, and naturally occurring microorganisms—such as yeast, Penicillium, Aspergillus, and Botrytis cinerea. Although cork taint had been recognized since the early 20th century, TCA wasn’t identified as the main cause until the 1980s.
2. How Does Cork Taint Occur?
While cork taint is most commonly associated with wines sealed with natural cork, contamination can also originate from winery equipment. In severe cases, an entire batch—or even an entire cellar—may be affected. Even wines sealed with screw caps can be tainted if they come into contact with TCA-contaminated environments.
The main causes include:
①Poor sanitation practices or the use of chlorine-based cleaners
If hygiene is inadequate during winemaking, fungi can grow, creating an environment where TCA forms. Similarly, using chlorine-containing cleaning agents on barrels or cellar walls can trigger TCA formation when these materials come into contact with wood.
②Use of certain wood preservatives and fungicides
In the 1990s, many wineries in France treated barrels and cellar walls with flame retardants or fungicides during renovations. These practices inadvertently encouraged TCA formation, contaminating wines in the process.
Additionally, certain winemaking materials can absorb TCA. For example, bentonite, a type of absorbent clay used to clarify wine, can trap TCA from its surroundings and pass the contamination on to the wine.
3. How to Identify Cork Taint
Cork taint is usually detected through smell and taste. Severely tainted wines display strong notes of mold, wet newspaper, damp basements, or burnt rubber. Mildly tainted wines may be harder to identify by aroma alone; in these cases, tasting helps determine the fault. Tainted wines often lose their fruit and floral notes, tasting flat, muted, and lifeless.
Identifying cork taint, however, is not always easy. Sensitivity to odors varies from person to person, and the presence of other strong aromas can mask the defect. Not every off-odor comes from cork taint either.
For instance:
- If a wine’s color is dull and the taste is flat or vinegary, oxidation may be the cause.
- If the wine smells like rotten eggs, excessive sulfur compounds may be responsible.
4. Can You Still Drink a Cork-Tainted Wine?
Cork taint affects flavor and aroma, but it does not pose a health risk. Technically, it is safe to drink.
However, discovering that a long-anticipated bottle has been spoiled can be deeply disappointing. If a simple table wine is severely tainted, most people will choose not to drink it. But when the bottle in question is a rare or highly valued wine, opinions vary.
Some argue that “a great wine is still interesting even with a slight flaw,” while others prefer not to drink it but may keep the bottle for sentimental reasons. Ultimately, it comes down to personal preference.
5. How to Reduce the Risk of Cork Taint
In recent years, the wine industry has taken many steps to minimize cork taint—such as eliminating chlorine-based cleaners and improving cork production, storage, and transport practices. Advances in testing technology have also helped.
For example, producers can now test raw cork bark for mold contamination before manufacturing. Portuguese cork giant Amorim has even developed gas chromatography technology capable of detecting trace amounts of TCA in natural corks within seconds—an impressive improvement compared to older methods that required several minutes.
Although cork taint remains one of the most common wine faults, there is no need for alarm. Thanks to modern improvements, the incidence rate is now very low. If a purchased bottle is confirmed to be tainted, consumers can usually contact the seller for a replacement. Understanding cork taint helps wine drinkers identify the issue more confidently and develop a more informed approach to evaluating wine.
