Trichloroanisole

Trichloroanisole (TCA) is a volatile chlorinated anisole, commonly identified as 2,4,6-trichloroanisole. It is best known for causing cork taint in wine, imparting a musty, moldy, or damp cardboard aroma at extremely low concentrations.

Chemically, TCA is C7H5Cl3O. It forms from chlorination of anisole or related phenolic precursors such as guaiacol in cork, wood, or packaging materials, often in the presence of chlorine-based sanitizers used in production and storage. The compound readily migrates into wine from closures or contaminated surfaces.

Occurrence and impact: TCA is most associated with natural cork closures but can also be present in synthetic closures and bottles handled with tainted packaging. Its odor is detectable far below typical sensory thresholds, often in the nanogram per liter range in wine, making even tiny amounts noticeable to sensitive tasters.

Detection and analysis: Because the odor threshold is extremely low, confirming the presence of TCA typically requires instrumental methods such as gas chromatography–mass spectrometry (GC-MS) or GC-olfactometry, in addition to trained sensory panels.

Prevention and management: The wine industry has shifted toward alternative closures, including synthetic corks and screw caps, to reduce cork taint. Practices that minimize chlorinated exposure—such as using non-chlorine-based cleaners and avoiding chlorine in cork processing—help lower TCA formation. Selective cork sourcing and quality control are also employed to mitigate risk.

Summary: Trichloroanisole is the primary chemical associated with cork taint, capable of rendering wine undrinkable at very low concentrations. Understanding its sources, detection, and prevention informs closure choices and production practices in the wine industry.