What is TCA and how does it affect wines?

Wine is a beverage enjoyed for its flavor, aroma, and complexity. However, it can sometimes be affected by a flaw that can completely ruin the experience: TCA.

What is TCA?

TCA, or Trichloroanisole, is a chemical compound with a characteristic musty or damp smell. It’s a very common defect in wine, and it’s estimated to affect about 4% of bottled wines worldwide. TCA, or Trichloroanisole, is a molecule that can contaminate wines and cause a defect known as “cork taint” or “corky smell”. This flaw is characterized by an unpleasant smell of wet cardboard, mold, dampness, or wet wood, which masks the wine’s own aromas and reduces its quality and sensory pleasure. Moreover, TCA can alter the taste of wine, making it more bitter, stale, or flat.

TCA: The Enemy of Wine

TCA is one of the most common and feared defects in the world of wine, yet not all consumers are able to detect it since its perception threshold varies depending on the person and the type of wine. Some experts claim that it can be perceived from 1 nanogram per liter, while others need up to 10 nanograms per liter to notice it.

How is TCA Produced?

TCA is produced from the reaction of chlorophenols, which are natural compounds found in cork, with chlorine. Chlorine can be used in the cork production process to kill bacteria and fungi, but it can also cause the formation of TCA.

What Causes TCA?

TCA is not a natural substance, but is formed by the reaction of chlorophenols with fungi. Chlorophenols can be present in the environment or in materials used in wine production and preservation, such as pesticides, disinfectants, wood, or corks. Fungi are microorganisms that can grow in conditions of adequate humidity and temperature, such as those found in cellars or bottles. The main source of TCA contamination is cork, as it can be infected from the tree of origin or acquire it during the manufacturing or storage process. Cork is a natural material obtained from the bark of the cork oak, a tree that can be exposed to chlorophenols present in the soil, water, or air. Additionally, cork can be treated with chemicals containing chlorine to clean, bleach, or protect it from pests. These factors can promote the formation of TCA in cork, which then transfers to the wine through contact. However, cork is not the only source of TCA, as it can also originate in other elements involved in wine production and storage, such as barrels, tanks, pipes, labels, or boxes. These elements can be contaminated by chlorophenols from external or internal sources, such as cleaning products, wood preservatives, or paints. Thus, TCA can reach the wine through airborne transmission or direct contact.

How is TCA Detected?

TCA is easily detectable by its characteristic musty or damp smell. If you notice an unpleasant odor when uncorking a bottle of wine, it is likely affected by TCA.

Expert Tasters in Detecting TCA

The detection of TCA is based on sensory evaluation performed by expert tasters or trained consumers. This takes into account the wine’s smell and taste, as well as its visual appearance. Some signs that may alert to the presence of TCA are:

  • A smell of wet cardboard, mold, dampness, or wet wood, which can be more or less intense depending on the concentration of TCA and the type of wine.
  • A bitter, stale, or flat taste, which can be more or less noticeable depending on each person’s sensitivity threshold and the type of wine.
  • A turbid, opaque, or discolored appearance, which can be more or less evident depending on the degree of wine oxidation.

If a wine is suspected to be contaminated with TCA, a simple test can be performed to confirm it: pour the wine into a glass and cover it with plastic wrap for a few minutes. Then, remove the wrap and smell the glass. If a stronger
cork smell is perceived than before, it is likely that the wine contains TCA.

What Happens if the Wine Has TCA?

While TCA is not harmful to health, it can ruin the taste of wine. If a bottle of wine is affected by TCA, it is better not to drink it.

How to Avoid TCA?

There are several ways to avoid TCA in wine. One of the most effective is using synthetic corks, which do not contain chlorophenols. It’s also important to store wine in a cool, dark place, to prevent contamination with chlorine.

How to Prevent and Treat TCA?

Preventing TCA is a challenge for the wine industry, as it requires exhaustive control of all factors that can intervene in its formation and transmission. Some preventive measures are:

  1. Avoid the use of chemicals containing chlorine in viticulture and winemaking.
  2. Choose cork suppliers that guarantee optimum quality and complete traceability.
  3. Apply effective and ecological cleaning and disinfection methods in cellars and equipment.
  4. Use alternative materials to cork for sealing bottles, such as synthetic or screw caps.
  5. Conduct periodic wine analyses to detect possible contaminations.

The treatment of TCA is difficult and costly, as once wine is contaminated there is no way to completely remove it. Some techniques that have been tried are:

  • Filtering the wine with activated carbon or polymeric resins to absorb TCA.
  • Oxidizing the wine with ozone or hydrogen peroxide to degrade TCA.
  • Adding substances to the wine that mask TCA, such as sugar, citric acid, or artificial flavors.
  • Exposing the wine to electric or magnetic fields to alter the structure of TCA.

However, these techniques have limitations and side effects, such as the loss of aromas, flavors, and color of the wine, or the generation of other undesirable compounds. Therefore, it is most advisable to avoid consuming wines contaminated with TCA and to request their replacement or return to the supplier.

Tips to Prevent TCA

If you want to prevent your wine from being affected by TCA, you can follow these tips that will help you prevent the appearance of TCA in your wines:

  • Choose options with synthetic wine stoppers, as they do not contain chlorophenols and cannot produce TCA.
  • Store wine in cool, dark places. Keep in mind that chlorine can contaminate wine if it is stored in a place with too much light or heat.
  • Watch out for the smell of mold or dampness, if you notice an unpleasant smell when uncorking a bottle of wine, it is likely to be affected by TCA.

TCA is a significant problem that can ruin the experience of enjoying a good wine. Therefore, it’s important to understand its causes, effects, and solutions. This way, we can avoid it, detect it, and claim it in case we encounter it. And above all, we can better appreciate the aromas and flavors of wines that do not have it.

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