Drinking wine is usually about slowing down and savouring a moment, whether you’re at the dinner table with loved ones, or enjoying a sunset all by yourself. But, every once and a while, that joy is sabotaged because your wine is corked.
What is corked wine?
Cork taint contaminates fewer than five percent of wines with natural corks. When it strikes, it gives wine a smell similar to wet newspaper or wet dog, and a taste many describe as dull and flat. That’s hardly the “bottled poetry” Scottish writer, Robert Louis Stevenson, was talking about.
The science behind the scourge
The presence of six chemical compounds causes cork taint. These are guaiacol, geosmin, 2-methylisoborneol (MIB), octen-3-ol, octen-3-one, and most importantly, 2,4,6-trichloroanisole (TCA).
TCA forms when natural fungi – many of which reside in cork – mix with chlorides found in winery sanitation and sterilisation products. Cork taint occurs when the TCA molecule infects a wine cork.
It only takes a level of two parts per trillion (0.000000000002 grams in a litre) of TCA in dry-white and sparkling wines to cause cork taint. In red and port wines, the level is five parts per trillion of TCA. Other, less common causes of cork taint (like MIB) strike after breaching a sensory threshold of 20 parts per trillion.
What’s that smell?
If the presence of TCA has caused the taint, the wine will usually have a musty, mouldy or wet hessian character. MIB and geosmin give off an earthy or muddy aroma, while guaiacol smells smoky or medicinal. Octen-3-ol and octen-3-one, on the other hand, smell a lot like tinned mushrooms.
Are you sure it’s corked?
Even experienced wine tasters might argue over whether or not a wine is corked. Why is that?
Well, to begin with, one person may be more sensitive to aromas than another. So, if the taint exists at a low level, it’s a given that many people won’t pick it up. In fact, the level of cork taint might be so low, it won’t be noticeable as a distinct smell. It will suppress the wine’s aroma and flavour, though. Under these circumstances, comparing the underwhelming bottle with other wines is the only way to tell whether it’s tainted.
People also adapt to the musty aroma of TCA very quickly, meaning that after continued sniffing, a wine’s perceived mustiness can fade. The take-away is that if you think a wine is corked after the first sniff, chances are you’re right.
And remember, though you won’t enjoy corked wine, it is safe to drink.
What to do?
Sadly, there’s no way to remedy cork taint because TCA is a very stable compound. Once it infects wine, it stays put – even outliving the wine. Also, allowing the infected wine to breathe won’t clean it up.
One solution is to return corked wines to stores or wineries. Another is to switch from corks to screw tops.
Corks vs. screw tops
Winemakers prefer to use corks for full, complex wines that benefit from the bit of oxygen they naturally let into bottles. The oxygen helps smooth out the tannins, leaving the wines feeling like velvet in the mouth.
By contrast, many winemakers prefer screw tops for white wines, and reds that are best drunk young. The screw cap doesn’t allow oxygen into the bottle, so the wine stays crisp and well-preserved.
Even the best wines are vulnerable to cork taint. So, as a wine drinker, it’s pretty much inevitable that you’ll open your fair share of contaminated bottles. But, like the best vines that thrive during some difficult harvests, your overall wine-drinking experience is what matters. And that is sure to be wonderful.