246trichloroanisole

2,4,6-Trichloroanisole, often abbreviated as TCA, is an organochlorine compound with the chemical formula C7H5Cl3O. It is the chlorinated derivative of anisole and is best known as the principal chemical responsible for cork taint in wine. TCA is detectable by the human sense at extremely low concentrations, often in the parts-per-trillion range, producing a musty, moldy aroma that is considered undesirable in wine.

Formation and occurrence: TCA is not an intended additive. It forms during cork manufacturing and storage when chlorinated phenolic compounds are transformed by environmental fungi and other microorganisms into the odorant. Sources of chlorinated phenols include wood preservatives, bleach residues, and chlorine-based sanitizers used in cork processing. The compound can migrate from cork stoppers or other packaging into wine during bottling and aging.

Sensory impact and detection: In wine, TCA can mask varietal characteristics and diminish perceived quality. Its odor is commonly described as musty or damp-cardboard, sometimes with earthy or moldy notes. Because the threshold is extremely low, routine sensory evaluation may miss contaminated lots, making analytical testing important for quality control.

Analytical methods and mitigation: Detection and quantification typically involve gas chromatography–mass spectrometry (GC-MS) or GC–olfactometry, often after sample preparation by solid-phase microextraction (SPME) or headspace techniques. To mitigate cork taint, wineries increasingly use alternative closures (synthetic corks, screw caps) and stricter screening and processing of cork stoppers.