CORK TAINT:
Do you have to exchange 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.

TCA can also arise at the winery

Which brings us to the last source of error. The winery itself. Here the guilty word is wood preservative. Which brings us from TCA to TeCA (tetrachloroanisole). One more letter - identical effect. Here, natural corks and wood preservative, which contains pentachlorophenol (PCP), form a compound that is responsible for the off-tone in the wine.

Und das kann sehr schnell gehen. Wenn in der Lagerhalle gerade die Regale frisch mit Holzschutzmittel behandelt wurden, eine Charge mit Naturkorken daneben liegt und der Raum nur unzureichend belüftet ist, zack! Korkschmecker! Wenn sich TCA oder eben auch TeCA erst einmal gebildet hat, können übrigens auch andere Verschlussarten damit verseucht werden. Zum Beispiel wenn TCA-Korken auf einer Palette lagen auf denen dann wiederum Schraubverschlüsse kurz zwischenlagern, kann es diese auch erwischen. Wobei das tatsächlich nur sehr, sehr selten vorkommt. Möglich ist es aber.

Action is required for defective goods

Which means we have now clarified that it is ultimately not possible to determine which production step can ultimately be held responsible for a corkton. In case of doubt, your customer doesn't care at all. She or he is disappointed and annoyed. You then have to react. In stationary retail, customers usually return the corked wine and receive a replacement bottle in exchange. This is exactly how it is regulated by law in most countries with regard to the warranty rights. In Germany, for example, Section 434 of the German Civil Code (BGB) applies, followed by other sections. However, as we do not provide legal advice, if in doubt, please contact a lawyer specializing in consumer law. Just as an aside.

If the wine or the vintage of the wine with cork is no longer in stock, the customer can insist on a refund of the amount paid. And if the replacement bottle is also corked, a partial refund is usually due. However, many wine shops will then refund the full amount as a gesture of goodwill. This is particularly common for premium wines that have been maturing for a long time.

You have the right to check the corkton

Of course, as a wine merchant you also have rights - and not just obligations. You can, of course, demand to check the faulty wine yourself. This is quite easy in the stationary trade. The customer just has to come by with the wine. Incidentally, if the wine is still drunk or the bottle is less than half full, you have some leeway. After all, consuming faulty goods is also consumption.

In online retail, handling a cork is more difficult. Of course, you also have the right to demand the return of a bottle that is at least half full. However, you will then also have to pay the transportation costs, i.e. the postage. The same applies if you send a replacement bottle. In this case, it is usually more economical to talk to the customer and offer a refund. You then simply write off the wine bottle with the cork. Whether online or stationary. This is still the best way to build a good relationship with your customers instead of engaging in endless discussions. This can destroy trust much more quickly than you would like.

290 million bottles of wine with corkton every year

Of course, it can still happen today that the entire batch of a wine has a cork. Such large quantities cannot be completely written off, even with an excellent tax consultant. In this case, a solution must be found with the next higher authority in the value chain. In other words, wholesalers, importers or wineries.

Incidentally, it may be that you personally only have to deal with the issue of cork in wine from time to time in your business. In 2022, around 29 billion standard bottles of wine with natural corks came onto the market worldwide. Statistically, one percent of these are said to be contaminated with TCA. That makes 290 million wine bottles with cork. That's not exactly a small number. It is therefore worthwhile for wine merchants to be clear in advance about how to deal with this problem with their own customers. And what the legal situation is regarding products with quality defects in your own country. After all, a cork is just such a quality defect. You should react accordingly.