2,4,6-Trichloroanisole Explained

2,4,6-Trichloroanisole (TCA) is an organic compound with the formula . It is the symmetric isomer of trichloroanisole. It is a colorless solid.

Occurrence

2,4,6-Trichloroanisole represents one of the strongest of off-flavors, substances "generated naturally in foods/beverages [that considerably] deteriorate the quality" of such products.[1] [2] It is also a component of some drinking waters.[3] It has also been detected in blood samples.[4]

Wine

As of 2000, TCA was considered the primary chemical compound responsible for the phenomenon of cork taint in wines,[5] [1] and it has an unpleasant earthy, musty and moldy smell.

Coffee

TCA has also been suggested as cause of the "Rio defect" in coffees from Brazil and other parts of the world,[6] which refers to a taste described as "medicinal, phenolic, or iodine-like". 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]

Formation

TCA is formed by the methylation of 2,4,6-trichlorophenol.[7] 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.[8] Species implicated include those of the genera Aspergillus, Penicillium, Actinomycetes, Botrytis (e.g. Botrytis cinerea), Rhizobium, or Streptomyces.[9] [10]

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.[11]

Notes and References

  1. 10.1073/pnas.1300764110. 1091-6490. Takeuchi, Hiroko; Kato, Hiroyuki & Kurahashi, Takashi . 2,4,6-Trichloroanisole is a Potent Suppressor of Olfactory Signal Transduction. Proceedings of the National Academy of Sciences. 2013-09-16. 110. 40. 16235–16240. 24043819. 3791788. 2013PNAS..11016235T. free.
  2. Book: Jackson, Ron S. . Wine tasting: a professional handbook . 2009 . Academic Press . 978-0-12-374181-3 . 2nd . Food science and technology international series . En . Chapter 3: Olfactory Sensations.
  3. 10.1016/0043-1354(95)00173-5. Taste and odour threshold concentrations of potential potable water contaminants. 1996. Young. W.F.. Horth. H.. Crane. R.. Ogden. T.. Arnott. M.. Water Research. 30. 2. 331–340. 1996WatRe..30..331Y.
  4. 10.1007/s002440010298 . Identification of Hydroxylated PCB Metabolites and Other Phenolic Halogenated Pollutants in Human Blood Plasma . 2002 . Hovander, t. Malmberg, m. Athanasia . L. . Malmberg . T. . Athanasiadou . M. . Athanassiadis . I. . Rahm . S. . Bergman . A. . Wehler . E. K. . Archives of Environmental Contamination and Toxicology . 42 . 1 . 105–117 . 11706375 . 2002ArECT..42..105H .
  5. Book: Marsili, R. . 2000 . Solid-Phase Microextraction: Food Technology Applications . Encyclopedia of Separation Science . Wilson, Ian D. . New Yor, NY . Academic Press . https://www.sciencedirect.com/science/article/abs/pii/B0122267702067910 . 10.1016/B0-12-226770-2/06791-0 . 4178–4190 . 9780122267703 . Over the last two decades, the incidence of mouldy and musty off-flavours in cork-sealed wines has increased significantly. 2,4,6-Trichloroanisole (TCA) has been identified as the primary chemical responsible for cork taint. The human olfactometry threshold for TCA is 4–10 ng L−1 in white wine and 50 ng L−1 in red wine. In the case of wine, a worldwide loss of roughly US$1 billion per year is attributed to cork taint..
  6. These include Central and South America.
  7. Spadone, Jean Claude; Takeoka, Gary & Liardon, Remy. Analytical Investigation of Rio Off-Flavor in Green Coffee. Journal of Agricultural and Food Chemistry. 10.1021/jf00091a050 . 1990. 38. 226–233. Note, at best, this source states that 2,4,6-trichlorophenol is "the probable precursor of TCA".
  8. Cravero . Maria Carla . Bonello . Federica . Pazo Alvarez . Maria del Carmen . Tsolakis . Christos . Borsa . Daniela . 24 June 2015 . The sensory evaluation of 2,4,6-trichloroanisole in wines: The sensory evaluation of 2,4,6-trichloroanisole in wines . Journal of the Institute of Brewing . en . 121 . 3 . 411–417 . 10.1002/jib.230.
  9. Web site: Crane . Louise . Trichloroanisole: Cork taint . 2024-01-14 . Chemistry World . en . 22 March 2019.
  10. With regard to circumstantial evidence, Spodone, et al., op. cit., note that Rio off-flavor is associated with "beans heavily infested with various fungi (Aspergilli, Fusaria, Penicillia, Rhizopus, etc.) and bacteria (Lactobacilli, Streptrococci)".
  11. NTP (National Toxicology Program). 2021. "2,4,6-Trichlorophenol", Report on Carcinogens, Fifteenth Edition. Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service. https://ntp.niehs.nih.gov/go/roc15

    DOI: https://doi.org/10.22427/NTP-OTHER-1003

    Further reading

    • Book: Marsili, R. . 2000 . Solid-Phase Microextraction: Food Technology Applications . Encyclopedia of Separation Science . Wilson, Ian D. . New Yor, NY . Academic Press . https://www.sciencedirect.com/science/article/abs/pii/B0122267702067910 . 10.1016/B0-12-226770-2/06791-0 . 4178–4190 . 9780122267703 . Over the last two decades, the incidence of mouldy and musty off-flavours in cork-sealed wines has increased significantly. 2,4,6-Trichloroanisole (TCA) has been identified as the primary chemical responsible for cork taint. The human olfactometry threshold for TCA is 4–10 ng L−1 in white wine and 50 ng L−1 in red wine. In the case of wine, a worldwide loss of roughly US$1 billion per year is attributed to cork taint..
    • Web site: Science Direct Staff . June 2023 . 2-4-6-Trichloroanisole . Science Direct citation sample/listing . June 26, 2023.
    • Buser, H.R.; Zanier, C. & Tanner, H.. Identification of 2,4,6-Trichloroanisole as a Potent Compound Causing Cork Taint in Wine. . Journal of Agricultural and Food Chemistry. 10.1021/jf00110a037. 1982 . 30 . 2 . 359–362. An early primary research report on the role of TCA in cork taint.

    See also

    References

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