A bad-tempered debate is raging in the wine business over corks. In a recent issue of the trade magazine, Harpers, the wine writer Malcolm Gluck snarled about another that "his nose is so much in the air he can barely see the mud in which he is so inelegantly stuck." The trade is worried about the number of bottles which are spoiled. For the public, "corked" is a generic term for a faulty bottle of wine. This is wrong. To be precise, "corked" refers to cork taint, caused by a reaction between a penicillium mould in the crevices of the cork and the chlorine-containing chemicals used in the sterilising process. The result is TCA (trichloroanisole), which has a fungal or mouldy aroma. This is not the same as oxidisation, another cause of bad wine (although it may also be caused by a defective cork letting in oxygen). An oxidised white wine is yellow or brown and can smell like madeira (hence it is "madeirised"), a red wine goes brown, and badly oxidised wines both red and white can have a vinegary aroma.
There is no agreement on how many corked bottles of wine there are, although everyone agrees there must be lots of them. The Wine and Spirit Association recently carried out a study which appeared to show that about 1 per cent of bottles are corked, but this result, and the methodology used, were widely rubbished, with other sources claiming that the true total is between 4 per cent and 8 per cent. At this year's International Wine Challenge, of the 12,000 bottles which were entered, 4 per cent were corked-480 bottles. If one in 25 tins of baked beans were found to be faulty, there would be an outcry.
What should be done? There are currently three main ways to close a wine bottle: natural cork, plastic stoppers, or screwcaps. Natural cork-the bark of Quercus Suber, the cork oak-gradually replaced wooden stoppers, beeswax or oil-soaked rags from the early 17th century (although cork stoppers had been known to the Romans, the knowledge was lost during the medieval period). For its defenders, only natural cork ensures the proper ageing of a good wine. They argue that minute quantities of air seep around and through the cork, allowing the wine to mature gradually; conversely, the tight fit of plastic corks prevents this. Who knows? There is no long-term comparative research to support their argument. Still, there is widespread agreement that for wines with the potential for long ageing, such as the great clarets or Rh?ne wines, or German rieslings, natural cork should be used.
However, in the early 1990s, supermarkets became tired of the high proportion of corked bottles, and put pressure on producers to find an alternative. Over the following few years, more than ten different types of synthetic cork crowded onto the stage and more continue to be developed. There are problems, of course: there is some loss of flavour, technically known as "scalping"; there can be plastic taint; plastic-stoppered bottles lose sulphur dioxide too quickly, thereby encouraging oxidation and premature ageing; and plastic corks are hard to extract from the bottle and almost impossible to push back in. Yet overall, they are better at protecting freshness and flavour than low-grade corks. The main problem is ageing. At 18 months the state of the wine does begin to decline, but since relatively little supermarket wine is much older than this, it does not much matter. And for fast-moving, lower-value wine, such as that of large-scale new world producers or the supermarkets' own labels, plastic closures are what they want.
And then there are the screwcaps, the most successful of the three in preventing oxidation. They give a perfect seal, do not cause taint or suffer from quality variation and can be opened with the bare hand. Indeed, they have been known to protect white wine for ten years, and their dependability has convinced Villa Maria, New Zealand's second largest winery, to go over entirely to screwcaps from the 2002 vintage. Villa Maria is a quality producer, and it will be interesting to see if they are followed by many other producers selling wine above ?5, the upper limit for 90 per cent of the wine bought by British wine drinkers. Or do screwcaps still remind too many consumers of opening a bottle of vinegar?
Most producers of premium wine, especially of red wine, use natural cork, not least because they believe that their traditionally-minded customers would be outraged if anything other than cork stoppered their bottles of wine. At a lower price level, and for wines which are meant to be drunk young, the use of plastic corks is widespread and will probably continue to grow. Screwcaps are largely used for the cheapest wines, although here and there, especially in Australia and California, the occasional quality wine producer is having a go.
But the status hierarchy is likely to remain between the metal screwcap, the length of extruded plastic and, top of the pile, the piece of bark. The ceremony of removal of a cork by a skilled wine waiter is a wonderful one, down to his suspicious sniffing of the cork. It will be with us for many years to come.
