Wine: The importance of the cork

Why should we still favour cork as a closure?
January 18, 2017

When does the enjoyment of a glass of wine begin? When you sip it? When you swirl it round in the glass to coax out its aromas? For me, it begins when you hear the cork being pulled from the bottle. The gentle squeaking as the cork is eased out followed by the satisfying pop when the aromas are first released. All this is part of the ceremony of serving and savouring a good bottle of wine.

Of course, not every bottle closure is made of cork. There are screw tops and plastic closures, which struggle to be in any way part of the ceremony or experience of enjoying a wine. I was once presented with the screw cap, which a sombre sommelier had slowly unscrewed from my chosen bottle. What was he expecting me to do? Smell it?

Of course, there are also Stelvin closures, which use a synthetic material to imitate natural cork. They adapt themselves perfectly to the shape of the aperture in a bottle’s neck; and of course they are removed with a corkscrew. But just try to get them back in the neck if you want to reseal the bottle.

The use of these alternatives to cork arose because of the hazard of contaminating the wine by a faulty cork. Cork taint, or TCA (2,4,6 trichloroanisole), is the highly volatile compound that dulls a wine’s aromas and lends it the smell of wet cardboard. The mere whiff of TCA and the wine is ruined for the drinker. This usually leads to a chain of compensation claims from a restaurant to a wine merchant to a winery, with all the fuss of sending back a faulty bottle or case. So why haven’t cork manufacturers eliminated it?

The answer is that it is extremely hard to detect and wine faults brought about by TCA may come from materials in the winery and not the cork. Cork manufacturers put a lot of work into detection. Specially trained noses are deployed to sample corks at random in a large batch and to put aside any that cause suspicion. Guaranteeing the health of each and every cork is possible but it costs much more to pass each cork under the nose of highly trained and sensitive sniffers. Technology is also being mustered with the DS100 process from Cork Supply Portugal, designed to ensure every cork is healthy.

With this risk, or expense, why should we still favour cork as a closure? Apart from the ceremony and the history, what other reasons are there for preferring cork? The answer is that cork is a natural substance, and has much more to give than it takes. Firstly, it allows the wine to breathe slowly in the bottle as it matures. That’s not because it allows the wine to interact with the outside environment but because there is oxygen in cork itself. Other airless closures do not afford the wine this capability, and as Randall Grahm of Bonny Doon explained to me, winemakers would have to make the wine differently for bottling with an airtight closure.

There is also the smell of good cork when it is released from the bottle. As the sommelier hands you a wine-stained cork to sniff this is your first acquaintance with the wine’s aromas, and they are delivered against the beautiful woody background note of a quality cork. No other closure plays this enhancing role.

The other reason to favour natural corks has to do with the whole ecology of the cork industry. I’ve heard it said that we should move away from corks to save the trees, but just the opposite is true. The cork forests of Portugal survive because we use corks in wine bottles. These forests with their unique flora and fauna thrive because the trees are nurtured for their bark, which is stripped every nine years, and grows back to become the next harvest of cork. The layers of bark are washed and cut into pieces. These are then punched to create corks that will be assessed for quality and colour before heading to wineries all over the world. The residue of this process is sent on to be ground into granules that will be glued together to make mats, flooring and Champagne corks. If Portugal didn’t make natural cork for the world of wine, it would be hugely more expensive to make other cork products. And as Californian wine grower Paul Draper has written, if we stopped using cork in wine bottles it would be an environmental disaster for the forests of Portugal.

So the next time you pull the cork from a bottle you will be playing your part in a time-honoured way of sustaining part of the nature and culture of the world of wine.