The expensive mystery of cork taint - the musty taste that has offended the palates of drinkers for centuries - is about to be solved.

The expensive mystery of cork taint - the musty taste that has offended the palates of drinkers for centuries - is about to be solved.

Wine experts are fed up with poseurs trying to impress their dinner companions in fancy restaurants by sending back perfectly good bottles - and ignoramuses who cry wolf because there are little bits of cork floating in their glass.

Now supermarkets and suppliers are to establish the first league table of wines susceptible to corking, which happens when a fungus gets into the bottle. The problem costs importers and retailers an estimated £300m a year - but the waste is exaggerated because so few ordinary drinkers can recognise corked wine properly.

"Over the years we have been sent hundreds of samples in which people have alleged cork taint when it isn't," says Geoff Taylor, whose company Corkwise analyses wines and spirits for the drinks industry.

The Wine and Spirit Association has commissioned the largest ever study of its kind, using quality-control experts from retailers such as Tesco and Somerfield to inspect thousands of bottles. The first results are expected in the spring of 2001.

A sommelier should detect the problem before the bottle reaches the table by smelling the cork and pouring the wine, says Antonio Carluccio, the television chef whose restaurants include Neal Street in Covent Garden. "When we encounter it, we immediately remove the bottle."

Unfortunately, the customer is not always right. "If a man is out with his new girlfriend or mistress he likes to show off and will say the wine is off when it may not be. That can be very awkward."

The musty taste associated with corked wine fungus is 2-4-6 trichloroanisole, or TCA. It often arises because of a badly fitted or impure cork but can also enter wine sealed with plastic, particularly if the bottles are not correctly washed. Cork taint seems more frequent than ever because of the huge growth in UK wine consumption in the 1980s. It is thought to affect up to ten per cent of all bottles sold, but the new survey will provide authoritative figures.

The London restaurateur Gordon Ramsay once had a customer who claimed that a £3,000, 1957 bottle of Petrus was corked. "I don't mind arguing with people, but if you've got a talented sommelier then you know what you're talking about." That wine needed to be left open for 45 minutes, but the customer insisted on drinking it immediately. "He was just trying to create a bit of a scene," says Mr Ramsay. "After half an hour he appreciated the flavours. Had we been weak then, we would have binned a very expensive bottle of wine."