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james laube's wine flights

New TCA Study Confirms Suspicions

The cork taint compound actually shuts down our ability to smell a wine
Photo by: Greg Gorman

Posted: Sep 19, 2013 5:00pm ET

A new study has revealed that 2,4,6-trichloroanisole, or TCA, the compound often responsible for corked wine, is responsible for more than just that off-putting moldy aroma: TCA actually blocks our olfactory senses. That cork-tainted wine impedes our sense of smell is no surprise to me. It's something some of us have been witnessing for years now, even if we didn't have the scientific backing.

The study out of Japan advances our understanding of TCA taint and how individuals perceive it. Mainly, the study asserts that it's not TCA that smells bad, but that TCA prevents us from smelling wine.

Those of us who have dealt with TCA and cork taint going back to the 1980s came at this equation from a different perspective, both because some of us are more sensitive to TCA, but also thanks to our experiences in blind tastings.

That individual corks were tainted could be observed by tasting other bottles that weren't tainted. But what struck many of us was what we called the "muted" aromas found in wines we came to suspect had low levels of TCA, or some other defect. Knowing that TCA taint can register in amounts as low as parts per trillion, making it difficult to detect, some of us suspected that some wines had a very low level of TCA that might not be readily identifiable as cork taint but that was nevertheless somehow interfering with our ability to smell a wine. Tasting a second bottle that showed fine convinced us of that possibility.

I routinely retaste wines all the time, perhaps as many as 10 percent. The primary reason is because I suspect something is off in the first bottle, be it cork taint, oxidization or heat damage. The cause matters less than realizing a wine might be off and a desire to be as fair as possible to any given wine. Most of the time, retastes merely confirm the original perception. But there are enough subtle nuances from time to time to remind us that each bottle sealed with a cork is a unique bottle and the possibility for bottle variation is higher than anyone of us would like to believe. It can readily explain why one person, or one critic, raves about a wine while another is non-plussed, or indifferent.

It's also a reason many of us favor alternative closures, such as twist-offs.

This study should be another warning to winemakers and consumers alike. Each week I talk with a dozen or more winemakers, and virtually all of them acknowledge the problems of cork taint and bottle variation. Many are also keenly aware of low-level TCA taint, the kind that isn't easily identified. Most don't change their closures, even knowing that corks are problematic. They're worried that a twist-off closure would cheapen their image. I wonder: If we knew exactly what percentage of wines truly contained those tiny 1 or 2 parts per trillion of TCA that are enough to mute a wine's aromas and flavors, but that might not set off most people's cork taint alert, would the wine industry finally stand up and do more to address this rampant flaw, by changing closures or by attacking it at the source, wherever that might be?

Robert Camuto
France —  September 20, 2013 2:27am ET
James: Enjoyed this post. But there's something none of the articles on the subject address that I am curious about. Does TCA alone indeed give off a perceived strong odor? IE Does TCA in otherwise odorless water solution create the same newspaper or cork taint impression as it does in wine? Or does it smell like something else?
Harvey Steiman
San Francisco —  September 20, 2013 12:18pm ET
Robert, kits of aromatics common to wine include one bottle with 2,4,6 TCA in solution. It reeks of the wet newspaper/mildewy character without any wine.
James Gerace
Phoenix, AZ, USA —  September 24, 2013 11:25am ET
James, thank for this. The number of flawed wines is far greater than anyone wants to admit. Sometimes so subtle we don't pick it up right away. Sent a bottle back to a winery, they did not agree and sent to a lab which confirmed 3.3ng/L. I keep hoping for fewer corks and less wine down the drain.
Don Rauba
Schaumburg, IL —  October 3, 2013 9:44pm ET
What I find most objectionable is the resistance to twist-off (and other alternative) closures. There's nothing "cheap" about wanting to ensure an unmarred experience for the customer. In fact, NOTHING could be of greater value to a wine consumer! If you make wine that's drinkable in 5 years, even 10 or 15, there is zero benefit to corking it. All you're doing by remaining "traditional" is ENSURING that 5-10% of your customers get a bad bottle. Why not ENSURE the OPPOSITE? A LOT of good brands have switched, in Australia, Germany, Austria, and even California (isolated examples literally everywhere). What sorry delusion stops everyone else from putting the customer first?

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