Cork or No Cork? The Science of Sealing Wine Bottles

Most of us couldn't identify a corked bottle of wine if it bit us on the nose, which is what concerns winemakers. Californian producer Carol Shelton says she would rather get a bottle returned than have the customer say to their friends, 'I don't much care for it.' "I suspect a lot of people decide they don't like our wine, when really, they don't like the taste of cork taint," she says. With an estimated 5-8% of bottles tainted, it's hardly surprising that winemakers are frustrated.

Some cork companies are working on ways of either removing TCA from corks or stopping the TCA moving from cork to wine (such as the membrane covered ProCork), but many winemakers are taking a more radical approach and abandoning the ubiquitous cylinder of tree bark altogether.

Alternatives to cork

Currently, synthetic cork and screwcaps are the two alternatives to cork that are widely-used. Synthetic cork is a squidgy bit of plastic that replaces the spongy bit of cork. It eliminates TCA contamination, but it's not for wines intended for long aging, since synthetics don't seal as well as natural cork, and wines under synthetic cork oxidize within a few years. If wine is oxidized, it means that oxygen has reacted with the ethanol (alcohol) in the wine resulting in ethanal - which makes the wine taste flat and dull. Around 90% of wine is consumed within 24 hours of purchase, however, so synthetic corks have a viable future, even if they will never replace natural cork entirely.