The Wine Column: Getting corked.....is the problem!

In the wake of Prince Charles' recent show of support for the cork industry, the Eden Project's cork piglets and stork may be joined by an Iberian eagle made entirely from cork too. For hundreds of years the cork oaks of Portugal and Spain have provided the material for plugging the tops of wine bottles, spawning by-products like the corkscrew industry and the cult of the supercilious sommelier. Why then, as the environmentally concerned Prince of Wales asked, should anyone want "to encounter a nasty plastic plug in the neck of the wine bottle"?

Because cork can't guarantee a fresh bottle of wine every time. Hence the growing use of plastic stoppers and screwcaps. With the huge demand for wine sold in bottles, the quality of corks has dropped and the cork producers of Portugal, although spending millions on trying to solve the problem of corked wine, have shown themselves incapable of coming up with a clean cork every time. The malodorous culprit in cork that produces offensively mouldy odours in some wines is the TCA compound.

One of the problems of a corked wine is that the off-odours of TCA can vary from the totally unacceptable to the barely perceptible. The difficulty of accurately gauging the percentage of corkiness allows the pro and anti lobbies to put their own spin on the number. So while the cork industry estimates that around three in 200 bottles are problematic, the wine industry puts it much higher. At this year's International Wine Challenge, the 12,000 bottles opened were closely monitored and one in 25 bottles were found to be corked. Either way, the number is unacceptable.

While acknowledging that some cork producers are genuinely trying to eradicate cork taint, Anne-Marie Bostock, who heads the Tesco wine-buying department, is annoyed by the cork industry's PR spin. Using its spring wine fair to launch 30 new wines with a screwcap in the £3.99 to £8.99 range, Tesco sold 1.5m bottles in 10 weeks. Meanwhile, independent in-store surveys showed that 60 per cent of customers thought screwcaps were a good idea, the majority preferring them because of the convenience.

The screwcap is not new but its slow progress as the obvious stopper, at least for everyday wines, is due to past association with cheap plonk. In fact, screwcaps, known by their brand name as the Stelvin closure, have been shown by scientific trials to be far the most effective seal for a bottle of wine. Contrary to myth, a cork should not allow a wine to "breathe" and air can get into the bottle if a cork contracts. The screwcap in contrast is airtight. Recognition of its benefits is behind the decision by a group of 13 Clare Valley Riesling producers, and latterly 27 producers of sauvignon blanc in New Zealand, to switch to screwcap for their premium aromatic white wines.

While Stelvin is considered particularly appropriate for aromatic whites, support is growing for screwcaps for premium red wines too. Australia's Jeffrey Grosset, for instance, has switched to screwcap for his top red Gaia "as a result of an urgent need to adopt a closure that meets the standard of quality control I employ in every other aspect of wine production". This is causing some producers anxiety that it might slow down the development of their top reds. Only the cynical would suggest that screwcaps might put a brake on the cash-flow from wine drinkers to the pockets of the wine trade.