Cork taint

This article talks about TCA, aka Tricloroanisole.

Cork taint is a broad term referring to an off-odor and off-flavor wine fault arising from the presence of 2,4,6-trichloroanisole (TCA), a chemical compound that represents one of the strongest off-flavors, and one "generated naturally in foods/beverages", in particular wines, that considerably reduces the quality of these products.

Cork taint is characterized by a set of undesirable smells or tastes found in a bottle of wine, especially spoilage that can only be detected after bottling, aging and opening. Though modern studies have shown that other factors can also be responsible for taint—including wooden barrels, storage conditions and the transport of corks and wine—the cork stopper is normally considered to be responsible, and a wine found to be tainted on opening is said to be corked or "corky". Cork taint can affect wines irrespective of price and quality level.

The chief cause of cork taint is the presence of the chemical compounds 2,4,6-trichloroanisole (TCA) or 2,4,6-tribromoanisole (TBA) in the wine, which in many cases will have been transferred from the cork, but which also can have been transferred through the cork rather than from it. TCA is a compound which does not occur naturally; It is created when some fungi are treated with chlorinated phenolic compounds, which are types of antimicrobial agents used in the processing of wood. This class of compounds is a chief factor responsible for the problem associated with mold liable to be found in corks; very small amounts of this compound, on the order of nanograms, can be responsible for this defect.

Corked wine containing TCA has a characteristic odor, variously described as resembling a moldy newspaper, wet dog, damp cloth, or damp basement; in almost all cases of corked wine, the wine's native aromas are reduced significantly, and a very tainted wine is quite unpalatable, although harmless. While the human threshold for detecting TCA is measured in the single-digit parts per trillion, this can vary by several orders of magnitude depending on an individual's sensitivity, where the detection limit is also complicated by the olfactory system's particularly quick habituation to TCA, making the smell less obvious on each subsequent sniff.