Cork taint is probably by far the most common wine defect in the world. Also known as cork taint, cork taste or simply TCA. As a wine merchant, you have to deal with it very often. But what are your rights and obligations when customers complain about a corked wine?
Yes, it can be a minor disaster. Sometimes even a big one. You're looking forward to enjoying a wine, pull the cork with relish, pour, swirl - and then this! The wine smells like a musty, damp cellar. Or like wet and perhaps moldy cardboard. This unmistakable musty note makes it easy to recognize the wine's fault immediately: Cork taint. Or cork taint. Professionals also like to simply call it TCA.
These three letters stand for trichloroanisole. 2,4,6-trichloroanisole, to be precise. This substance is produced by microbial methylation of trichlorophenol (TCP). That sounds terribly complicated at first. Welcome to the world of chemistry! But it can also be simpler. Roughly speaking, TCA is formed when chlorine-containing substances come into contact with the phenol in natural corks. And this can happen in several places at once, as Professor Hans Tanner from the Swiss Federal Research Institute in Wädenswil, Switzerland, first discovered in 1981.
Corkton: How TCA can develop
On the one hand, TCA can be found on the cork oak itself. This is because the cork oaks in Portugal in particular were literally fleeced until the 1980s. In order to allow new bark to form unhindered, a pesticide containing chlorine was increasingly used at the time. Today, this is only used to a limited extent, but this does not change the fact that the infamous corkton can develop. On the other hand, forest fires can also produce similar chemical compounds, which then introduce TCA into the bark of the cork oak. Such large wildfires unfortunately occur regularly on the Iberian Peninsula.
However, there are two other possible sources of corkton. Until the 1990s, closure manufacturers bleached wine corks with chlorine. After that, they switched to hydrogen peroxide on a large scale, but the number of faulty corks did not decrease, as similar chemical compounds are also produced here. Only further high-tech processes and artificial corks ensured that the number of corked wines fell.