How to spot a corked wine - Ask Decanter

The cork industry says it has invested heavily to cut cork taint levels. Credit: Photo by Andres Siimon on Unsplash

Corked wine at-a-glance:

How do you spot a corked wine? Look out for a damp cardboard, mouldy or wet dog smell that also dulls the fruitiness of the wine.

What causes it? TCA, also known as 2,4,6 – trichloroanisole, is the main culprit but it has other family members.

Is it bad for you? It might put a dampener on your dinner party, but cork taint is not considered harmful to health.

How common is it? That depends on who you ask, but the natural cork industry says it has significantly reduced the risks in recent years.

Can screwcap wines be ‘corked’? Technically yes, you can have ‘cork taint’ aromas because contamination can happen in the winery, but this isn’t thought to be as common.

Myth buster: This problem is not related to bits of cork floating in your wine, albeit this isn’t a strong look and may mean the cork has dried out in the bottle or wasn’t of great quality in the first place.

Where does cork taint come from?

There is a grey area about exactly what constitutes a fault in wine; you’ll find widely divergent opinions on brettanomyces, for example.

But cork taint, commonly known as ‘corked wine’, is one of the ‘undeniable flaws’ as Natasha Hughes MW wrote in her Decanter article on wine flaws a few years ago.

A potent compound with the catchy title of 2,4,6 – trichloroanisole (TCA) was identified as the main culprit of cork taint by researchers writing in the Journal of Agricultural and Food Chemistry in 1982.

They conducted tests on European red and white wines and found that even tiny quantities of TCA could spoil your wine enjoyment.

TCA is part of a group of compounds known as haloanisoles and it can be formed following a reaction between plant phenols, mould and chlorine.

Cleaning products containing chlorine were considered a major problem in both the cork industry and in the winery, but efforts have been made to reduce this source of contamination. Using chlorine to help make corks is banned, according to Apcor, the Portuguese cork association.

However, studies have shown that TCA can also form on tree bark, prior to cork production, and can also contaminate equipment in the winery.

Other compounds in the same family have been associated with cork taint-like aromas in wine, albeit less frequently.

Among them, TBA – or 2,4,6-tribromoanisole – has been traced to preservatives used to treat wood in the winery, for example. Again, wineries have changed processes to help avoid the problem.

How to spot a corked wine

Does your wine smell like a damp cardboard box or a wet dog? Has this aroma masked the fruitiness of the wine so that it’s all a bit dull on the nose?

If so, there’s a good chance that you’ve got a corked wine on your hands.

Yet it’s impossible to speak in absolute terms. Cork taint happens by degrees and some wine lovers, whether by sensory training, experience or natural sensitivity, may pick it up more easily than others.

Cork taint can sometimes cause debate among even the top experts during a tasting.

Estimates vary on how significant the issue still is. The cork industry has estimated around 1% of wines are affected, but other estimates have ranged between this and around 8%. It may partially depend on when the wine was produced.

Prevention and developments

Cork taint is very hard to spot in the winery before it’s too late, because only a small amount of contamination is needed to spoil the wine.

Prevention has been key and some top wineries, notably in Australia and New Zealand, have switched to screwcap in the last 15 years or so – citing cork taint as a motive.

But, the cork industry says it has invested heavily to reduce the problem.

Among the most recent developments, natural cork producer Amorim launched new technology that it said would improve its ability to check for TCA on its own production lines.

Amorim said the technology, known as NDtech and officially launched in 2016, allowed it to deliver corks with a ‘non-detectable TCA guarantee’.

Cork producer Diam also offers a guarantee on its stoppers, by using what it describes as a patented ‘de-aromatisation’ process, as examined by Decantercolumnist Andrew Jefford in 2014.

Translated by Leo / 孔祥鑫