Have you ever opened a bottle of wine just to find out that it smells rather like mold from wet paper, absolutely killing your aroma expectations raised by the claims on the back label? Such a frustration! But the truth is that corked wine is an unfortunate experience that many wine lovers have been through.
The contamination of wine from cork smell is mainly caused by a chemical compound called TCA, AKA trichloroanisole.
TCAs, as well as other undesirable odors that may occur in water, soil, the cork itself and any other source during the bottle production process (containers during transport, warehouses, etc.), are associated with fungi spread to the wine, dramatically affecting its smell and taste.
The most important part of the story is this: Cork is not necessarily the source! It simply is the conduit through which the contamination occurs. And most of the times it is extremely difficult to locate the primary source of the infection! The use of traditional cork always leaves a small possibility (sometimes bigger) for unpleasant surprises during opening the bottle, even when referring to high-end wines.
Cork manufacturers claim that the quality of the corks used is constantly improving and they might be right. In today's market, expensive cork solutions are in place to ensure that wine is not affected by the cork itself, still those quality stoppers haven’t yet managed to fortify against infections from other sources. This is why more and more wine-makers around the world adopt screw caps.