How to detect cork taint by smell?

Cork taint is wine's most common fault, and learning to spot it is one of the most useful skills any wine drinker can develop. Once you've smelled it, you'll never forget it.

The classic descriptor is 'wet cardboard.' That's spot-on — it's a musty, damp, basement-like smell that immediately kills any fruity or floral character. Other descriptions include mouldy newspaper, damp dog, and old cellar. In severe cases, you'll notice it the instant you pull the cork. In mild cases, it's more subtle — the wine just seems oddly flat and lacking in fruit, without an obviously 'off' smell.

The molecule responsible is TCA (2,4,6-trichloroanisole). It forms when naturally occurring fungi in cork bark come into contact with chlorine-based cleaning products — a reaction that produces this incredibly potent contaminant. How potent? Humans can detect TCA at concentrations of 1.5-3 parts per trillion. That's astonishing sensitivity — roughly equivalent to detecting one drop in 800 Olympic swimming pools.

Here's a three-step detection method. First, pour a small amount and sniff without swirling — a major taint will be obvious immediately. Second, swirl and sniff again — this releases more volatile compounds and may reveal subtler contamination. Third, taste — a corked wine will taste flat, with muted fruit, a short finish, and possibly a bitter aftertaste.

An estimated 2-5% of wines sealed with natural cork are affected — that's potentially one bottle in every case of twelve. This is exactly why the wine world has moved toward alternatives: screw caps (dominant in New Zealand and Australia), synthetic corks, and treated cork products like Diam (which uses supercritical CO₂ to strip TCA from natural cork).

If you suspect a bottle is corked at a restaurant, don't hesitate to send it back — any good restaurant will replace it. At home, if you're unsure, try pouring a fresh glass after 30 minutes. A truly corked wine will smell worse as it opens up (unlike reduction, which fades with air).