2,4,6-trichloroanisole
2,4,6-Trichloroanisole
Chemical primarily responsible for cork taint in wines (TCA)
2,4,6-Trichloroanisole (TCA) is a chemical compound that represents one of the strongest of off-flavors, substances "generated naturally in foods/beverages [that considerably] deteriorate the quality" of such products.[1][2] As of 2000, TCA was considered the primary chemical compound responsible for the phenomenon of cork taint in wines,[3][1] and it has an unpleasant earthy, musty and moldy smell.[2]
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Chemically, TCA is a chlorinated derivative of anisole, and it is a formed by the biomethylation of 2,4,6-trichlorophenol.[4][5] More generally, it may be produced when naturally occurring airborne fungi and bacteria are presented with chlorinated phenolic compounds, which they then convert into chlorinated anisole derivatives.[6] Species implicated include those of the genera Aspergillus, Penicillium, Actinomycetes, Botrytis (e.g. Botrytis cinerea), Rhizobium, or Streptomyces.[7][8][6]
The chlorophenol precursor, 2,4,6-trichlorophenol, is used as a fungicide; more generally, related compounds can originate as contaminants found in some pesticides and wood preservatives, or as by-products of the chlorine bleaching process used to sterilize or bleach wood, paper, and other materials.[9]
TCA has also been suggested as cause of the "Rio defect" in coffees from Brazil and other parts of the world,[10] which refers to a taste described as "medicinal, phenolic, or iodine-like".[5] In investigation of the mechanism of its role in producing off-flavor effects, it was found to "attenuate olfactory transduction by suppressing cyclic nucleotide-gated channels, without evoking odorant responses."[1]