Waiter, this wine tastes like crap!
If you've ever suffered the appalling indignity of opening your favorite bottle of vino only to discover that it's "corked" on your first sip, you know that "wet cardboard" or "moldy, damp newspaper" are more appropriate descriptors. Cork taint is one of the most often discussed and also unforgettable defects to afflict the humble juice of the gods. Today cork blight is though to contaminate anywhere from 2-10% of the world's wine, which extrapolates to the sound of $650 million dollars worth of wine gurgling down the kitchen drain. (And now a moment of contemplative silence). The chemical implicated in this musty mess is "TCA," one 2, 4, 6-tricholoranisole. Its scent profile ranges from wet, moldy newspaper or cardboard to damp basement to moldy, dirty socks to musty mildew, and even "nasty chlorine-y" and wet, dirty dog, none of which elicit any sort of olfactory pleasure. In fact, severe cork taint renders most wine resolutely undrinkable. And the biggest problem is that we humans have a rather low sensory threshold for this chemical, noted as 5 parts per trillion per online sources and 4 ng/L in my textbook. At 10ng/L of TCA, a wine is considered significantly damaged. In other words, a little TCA can go a long way. It is also worth noting that other chemicals, like TeCA (2, 3, 4, 6-tetracholoanisole), also cause moldy, unpleasant off-odors in wines, but it is TCA that originates most specifically from cork. But do understand dear readers that TCA doesn't happen into existence on the back of some hapless, sad-sack, unsuspecting sheet of cork. To release its evil odor requires a partner - fungus.
In my 5 minutes of very extensive internet research, I discovered numerous wine websites that incorrectly indicted TCA as the responsible fungus, when in reality the chemical compound TCA is a by-product of fungus metabolism. As it turns out, common airborne, wood and soil dwelling fungi, like Penicillium, Aspergillus, Trichoderma, and Streptomycetes, are plucky enough to salvage "edible" carbon energy from unusual substances like cork. When desperate for food, the fungi degrade the cork's long carbon chains into usable energy, and in the process, liberate volatile phenols (smelly chemicals) that integrate with the wine and alter its aroma. Eliminating either their food source or the fungi is not that easy. Even after corks are boiled and chlorinated for sterility, fungi still eat them, especially in a damp, humid, poorly-ventilated cellar, where the hungry, microscopic critters generally lurk. And the story stretches even further back into the dark haunches of the soil-packed cellar wall. In fact the TCA actually evolves from a chlorinated derivative, called chlorophenol. In other words, fungi spin an odorless chlorophenol into 2, 4, 6-trichloroanisole. A-ha! If you think it sounds like "chlorine," then you're right. Researchers speculate that the very chlorine based disinfectants and sterilizing/bleaching agents used in wineries provide the "Cl's" that the fungi need to manufacture TCA. Today wineries in the know are phasing out chlorine-based chemicals in favor of high temperature autoclaving.
Tenacious molds may discover good eats not only in the carbon sources of cork but also in the carbon found in wooden containers, the walls of a humid wine cellar, or even in wooden transport pallets, storage crates, and timber accented roofs. In other words, once entrenched, the fungi can contaminate an entire winery and ruin batches and batches of wine. Indeed this is what happened at Beaulieu Vineyards which let 3 vintages lapse (1997-1999) before laboratory tests confirmed that BV was infected with TCA. Even our new favorite winery, Hanzell, once suffered in the clutches of TCA - an expensive problem that briefly halted sales of the 2000 chardonnay and required a complete winery overhaul with new hoses, equipment, ventilation systems, and alternative sterilizing techniques. They've since shared their extensive knowledge with other wineries, teaching other TCA-plagued wineries how to cope with this irksome problem.
Most often, corked wine is carried out to sea by way of our trusty sewage system, but back in January, Harold McGee (my favorite food scientist) divulged some intriguing data. In a January New York Times column, Mr. McGee talks with UCD wine chemist Andrew Waterhouse who claims plastic saran wrap can remove the offending odor of cork taint. Apparently, the chemical structure of plastic wrap, known scientifically as polyethylene, is pretty similar to TCA. Waterhouse counsels to simply pour ones blighted beverage into a bowl and toss in a smooshed up sheet of plastic wrap. Mix, pause, and then poof! The TCA "sticks" to the plastic wrap and malodorous phenols disappear; wine's as good as new. In the article, Mr. Waterhouse admits, "It's kind of messy, but very effective in just a few minutes." Another wine writer's column, The Cellarist, put this theory into action and found the "corkiness" indeed diminished but the fruity characteristics were reduced as well. But better reduced than undrinkable, right? At least you can still spike your spaghetti sauce.
Ever timely, even the latest issue of Wine Spec weighs in with a short bit on TCA and your health. The mag assures its readers that consuming TCA-tainted wine poses no known health risks. Pascal Chatonnet of University of Bordeaux notes, "Don't worry about your health, there is absolutely no risk. However, there is also no pleasure in tainted wine." Here, here! So the next time you dine in a fancy A-list restaurant and you find yourself nose-to-nostril with a strong whiff of TCA, by all means, send that wine back. Or better yet, embrace your inner Mr. Wizard and ask the wait staff for a sheet of plastic wrap from the walk in behind the kitchen. You may impress the sommelier enough to garner a free bottle of booze on your next visit!