TCA or 2,4,6-trichloroanisole is a potent taint compound associated with musty odours and flavours in a range of food and beverages. It is the unpleasant-smelling compound most commonly considered responsible for cork taint. The formation of TCA begins when chlorine reacts with organic phenols to form chlorophenols such as trichlorophenol (TCP). These in turn react with mould in the presence of moisture to form TCA. The enzyme methylase acts as a catalyst. Such phenols are present in all organic matter and are highly prevalent in the winery—in corks, barrels, wooden pallets, and in wood used in the structure of the building such as beams. TCA is extremely potent, with an aroma threshold in wine of 2–5 ng/l in red and white wines, reduced to 1–1.5 ng/l in sparkling wine because the carbon dioxide volatilizes taint compounds. A recent study by Chatonnet found evidence of TCA in new barrels, a finding fiercely contested by French coopers.
