June 2, 2016 | By RJS Craft Winemaking
Have you ever opened a bottle of wine that you thought would be outstanding, but after placing your nose into the glass you were shocked by the smell of a wet, moldy basement? This is never a pleasant experience for any wine drinker. But it is even worse when the wine is one you made yourself, pouring time and energy into it. Where does this unpleasant odor come from in a small number of wines? Let me tell you about cork taint and TCA!
Cork Taint is TCA!
TCA, also known as 2,4,6-Trichloroanisole, is a nasty little chemical compound which is responsible for the off aroma referred to as “cork taint”. It has such a low odor threshold that even at tiny concentrations of 2 to 3 parts per trillion, it can completely ruin the pleasant aromas of any wine. To give you an idea of how miniscule that amount is, it could be compared to 3 seconds in nearly 32,000 years or 1 ounce of water in 7.5 billion gallons. Crazy isn’t it?!
TCA normally develops as a consequence of fungal growth on or in corks, or from the use of a certain fungicides on cork trees. It is the interaction amongst these plant phenols found in cork, with mold and chlorine that give rise to TCA, which can then be transferred into the wine after bottling.
To make matters even more complicated, TCA taint can also originate in the winery where chlorine based cleaning products are occasionally used along with phenols originating from barrels, wooden pallets, wood beams, and cardboard boxes. So if you thought using synthetic cork closures would completely eliminate the presence of cork taint, think again!
How to identify it?
At higher levels, TCA can produce musty, moldy, aromas that smell like wet cardboard or a damp basement. At lower levels TCA can strip a wine of its flavor making it taste flat and dull. It is important to note that different wine drinkers will perceive TCA at different concentrations depending on their genetic background or their overall experience tasting wine.
Preventing Cork Taint?
Although there is no way to completely eradicate TCA taint in wine production, there are methods to reduce the chances of it contaminating your wines.
- Do not use chlorine based cleaning products, such as household bleach, but instead use percarbonate based cleaners such as OxyClean or Oxy-San, PBW, and B-Brite Cleanser
- Never soak your corks in sulfur dioxide solutions as this can pull certain off aromas from the corks, giving the wine a moldy or earthy aroma.
- If you sanitize the corks prior to use, place them in a container filled with sulfur dioxide gas. To accomplish this you can mix ¼ teaspoon of sulfite and ¼ teaspoon of citric acid in 1 liter of water. Place the corks just above this solution in a strainer to ensure the corks stay dry.
How common is Cork Taint?
Some reports have cited as much as 15% of all wines will have some level of TCA taint, while other reports claim that only 1% of wines are tainted. Fortunately, the majority of wine drinkers are unable to detect TCA or, at least they don’t know how to identify it. Nonetheless, we will all drink better wine if we can eliminate it. If you have any concerns about possible TCA taint in your wine, I would be happy to review your processes to help you minimize your risk.
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Chris Holman has been making wine professionally since 2006, which has led him to work in regions such as the Niagara Peninsula, Okanagan Valley, McLaren Vale South Australia, and Tasmania. Chris earned a 2 year diploma at Niagara College in Winemaking and Viticulture in 2008 and more recently he received a 4 year B.Sc degree majoring in Oenology and Viticulture at Brock University in 2015. His academic achievements in addition to his technical winemaking experience will allow him to provide our customers with excellent technical support and new ideas, helping them continue to make excellent wines.