Inquiring Winemaker


Is Barrel TCA the New Cork Taint?

January 2011
by Tim Patterson
Is contamination of French oak barrels by TCA the new cork taint? Or is this just old news wrapped in fresh press releases? That question may be the biggest 2010 year-end controversy in the wine trade, overshadowing old reliables like whether screwcaps make for clean wines or reduced wines, or whether genetically modified yeast is a swell idea or a non-starter. The eruption of interest in barrel taint began in late summer, when Pascal Chatonnet of the Excell Laboratory in Bordeaux announced research indicating that the incidence of TCA contamination in new French oak barrels was higher than previously assumed, that the problem was increasing and—worst of all—that the origin of the troubles was as yet unknown. The findings were accepted for publication in the Journal of Agriculture and Food Chemistry and made available on the journal’s website.

While research to identify the source of the problem continues, Chatonnet and the Excell Lab also offered a temporary fix: a testing protocol that could help cooperages and wineries separate the bad barrels from the good for anywhere from $5 to $15 per barrel.

Needles to say, the oak folk were not amused.

Grumpy coopers
Since Wines & Vines is a family-oriented wine trade magazine, I can’t reproduce some of the comments being made about Monsieur Chatonnet and his lab mates. However, you can construe the flavor from my conversation with Francois Peltereau-Villeneuve, president of Seguin-Moreau Napa Cooperage, which started with, “It’s nothing but a scam, a way to make money by scaring people off. Here you have a guy who says, ‘Look at how bad this problem is, how terrible the issue.’ And on the other hand, ‘Relax, I have a solution. It’s the end of the world, but…’”

Chatonnet’s announcement was immediately countered by a statement from the French Federation of Coopers, calling the allegations that coopers underestimate the risks of cork taint in new barrels “inaccurate and demeaning to the French cooperage profession.” The Federation’s press release went on to detail their own findings about the extremely low rate of barrel contamination and the variety of steps they and member cooperages—representing virtually all of France’s wine barrel production—have taken for several years to deal with problem.

In the journal article, press releases and interviews, Chatonnet has repeatedly raised the analogy to the problem of cork taint. In the 1990s, as evidence mounted that a significant proportion of natural corks were damaging the bottles of wine they stoppered through the presence of TCA (2,4,6-trichloroanisole), the major cork suppliers—as they now readily admit—responded at first by denying that the problem existed, denouncing critics and relying on their effective monopoly of the closure market. It took nearly a decade, multiple wake-up calls and the emergence of synthetics and screwcaps as major market forces to get the cork companies to seriously address the problem.

As Chatonnet told the Wine Spectator in early October, “It’s like the same situation with corks 15 or 20 years ago....The cork-makers were very resistant, especially the cork-makers with a high percentage of problems. I am not saying we have bottles tainted on the table now because of a problem of the barrel. I am saying if the cooper doesn’t do what’s necessary to do today, maybe in 10 years it will be too late.”

It’s almost impossible not to apply the cork taint analogy to the current barrel TCA flap. In both cases contamination can happen from a wide range of sources and in a wide range of situations: the use of chlorine in processing, or even in the vicinity; residues from wood preservatives and pesticides in production facilities; during production, storage and transit. In both cases, there are a number of chemical pathways to get to the same disagreeable result—and a whole family of unpleasant anisoles and their precursors besides TCA itself: TCP, TeCA, TeCP, TBA and so on. And in both cases, the problem can never be reduced to zero incidences, since cork and wood are natural, porous products unlike plastics, aluminum or stainless steel.

The cork story contains two more crucial elements. First, the problem was quite substantial when it was identified in the early 1990s. (Estimates ranged from 5%-10% of corks being infected, and complaints from both consumers and industry professionals were widespread.) And second, the cork industry tried to stonewall the problem for years before deciding to invest tens of millions of dollars in new technology and processes. The question is, do these two legs of the cork taint analogy hold up for the barrel taint flap?

How big is the problem?

The Federation of French Coopers says that based on its research and monitoring in recent years, somewhere around 0.03%-0.04% of new oak barrels carry some TCA, which translates to a little more than 100 barrels per year in the overall French production of 500,000 new barrels.

Chatonnet’s estimate is that the incidence is five to 10 times higher, probably in the 0.15%-0.25% range, but that since we do not know all the sources of the problem, every barrel is at risk. He argues that the problem has been underestimated because TCA may be present only in small, localized, unpredictable areas of staves, and it can be found deep enough inside staves to be unaffected by the toasting regimen for barrel production. His hypothesis is that the contamination is happening somewhere during the drying of staves, and some form of microorganism is involved.

Neither of these figures is very large—certainly not the same order of magnitude of cork taint in its glory days. But it is certainly possible for a bad barrel to doom a small producer’s boutique cuvée, or knock the fruit out of a whole tank. One bad cork ruins one bottle; one bad barrel can multiply its effects.

One difficulty in gauging the extent of the barrel taint problem is that no one really knows how you sample half a billion barrels. (OK, you could use the Excell Lab test.) The Federation of French Coopers has an oversight commission that collects and analyzes data about suspicious barrels. Chatonnet’s research analyzed several barrels from several coopers over several years—all of them bad barrels, in search of the origins of the taint—and his broader estimates are based on his general sense of t he industry, not rigorous sampling.

I did some non-rigorous sampling of my own. Mel Knox, who brokers barrels from Taransaud and Francois Frères in Northern California, says he has gotten “very few complaints about barrel TCA, ever,” including two calls in recent years claiming 2 parts per million TCA in wine in barrels. (That’s enough to create a sensory problem.) He contrasts the current standards for winery products in general, not just barrels, with those of 20 years ago: “In the old days, when I sold bottles, you would get containers, open the door, and it smelled like the eighth grade physical education boys locker room. I’d have to get the bottles washed.”

Gordon Burns at St. Helena, Calif.-based ETS Laboratories, which has much experience working with wineries in testing for TCA contamination in various forms, agrees that the problem of new barrel TCA, while real, is comparatively small. “Barrel TCA is one potential source of contamination, but not a major source. There’s nothing new on the front that barrels can be a source, but also no increasing incidence that we have seen. Barrels are a small part of the source of anisoles.”

Enologist Christian Butzke at Purdue University has spent years on the trail of TCA, primarily in corks. He agrees that there are many ways new barrels could become tainted, but he sees no evidence that it actually happens on a large scale. “We’re not seeing whole batches of wine tainted,” he says, “and there’s no history of TCA contamination in all those years of Bourbon barrels.” He acknowledges that barrel TCA can happen, just like cork taint, but offers his own distinctive analogy: “Serial killers are not a major source of homicides.”

One possible reason why barrel-tainted wine has not shown up in the marketplace, at least not in any volume, is that TCA contamination is fairly easy to sniff out in the winery. Winemakers and cellar staff use their own sensory equipment to spot suspect barrels long before they have samples go through laboratory testing. This may entail dumping some wine, but there is less likelihood that the moldy taint will head for the shelves. Genuine cork taint, by contrast, only shows up after bottling.

But even with this final line of defense, TCA-infested barrels are clearly something coopers need to worry about. Aren’t they?

Cooperage practices
The suggestion that cooperages are asleep at the switch is undoubtedly what has them most peeved. Singly and collectively, the major French cooperages insist that they have been on top of the problem for years, working on it vigilantly, and that they certainly know as much about barrel TCA as Chatonnet.

Besides the work undertaken by the Federation of French Coopers, individual cooperages have run their own research and imposed their own controls during the past few years. “My two cooperages (Taransaud and Francois Frères),” says Mel Knox, “have gotten religion, gotten to work.” He says that in 2001 Taransaud started to take protective measures: They stopped buying wood from anyone who also made wood for construction work, since that could be contaminated by sprays. Wood coming into the yard is quarantined and tested first, and the cooperages have TCA air traps. They also test for TCA in shipping containers.

Bruno Remy, sales manager for Canton Cooperage, which is owned by Taransaud, says that it’s a nightmare to find the source of TCA contamination, but that Taransaud, Canton and their Hungarian affiliate have gone to some lengths to develop techniques and controls. “Besides the staves, we check the heads, too. For every barrel, we have a tracking system for every part. We track the bungs, the packaging and the flour paste that holds the heads on. We test all the containers for shipping.”

“We’ve been working on this for years,” says Francois Peltereau-Villeneuve of Seguin-Moreau, even working for a time with Chatonnet and Excell. “Since 2006 we have instituted drastic specifications for all our suppliers—for wood, for metal, for anything that comes into the cooperage. We audit those suppliers once a year. All the water used to spray wood staves goes through sterilization and filtration; the water we extract (during heat-drying) gets analyzed, every lot. We have air traps and air filters. The protocols are thick as a phone book.”

One thing most cooperages do not do is retest barrels once they arrive in the U.S. In the case of cork, the Cork Quality Council, a consortium of major cork suppliers, supplements the efforts of cork producers by testing incoming batches of corks through a sampling protocol. The French cooperages mainly do quality assurance in France. At ETS, which has worked with the Cork Quality Council on its U.S. testing program, Gordon Burns says, “We have not seen evidence that the problem is significant enough to justify routine sampling on arrival in U.S.”

It’s entirely possible, as Chatonnet argues, that there are novel sources of contamination for which no one is properly controlling. But it’s clear that the cooperages are taking the problem more seriously than their cork cousins did in the 1990s.

Tainted reputation
Returning to the cork analogy one last time, complaints about corked wine eventually meant that natural cork had not just a technical/chemical problem but a major reputation problem. Wineries that may not have encountered serious trouble of their own got scared by horror stories. Natural corks became an all-purpose villain. “Waiter, this bottle is corked,” is routinely invoked by consumers for everything from real, live TCA to a bad vintage in Pomerol. Still today, natural cork has a reputation in some quarters that is arguably worse than the product’s actual performance.

Chatonnet’s article cites an object lesson in tainted reputation. He references an unnamed French cooperage that received complaints from California users concerning 0.15% of their barrels, which resulted in a 50% loss of share in this market. Major changes in production methods put an end to the complaints, the article continues, “but this only resulted in a slow recovery in sales. Consequently, even a small percentage of defective products may have major mid- to long-term repercussions on an industrial and business level.”

The Wine Spectator article, which received wide attention, contains a balanced treatment of which side says what in the dispute. But it ran under a rather alarmist headline—“Are French Barrels Corking Your Wine?”—and offered that teaser to a huge audience of non-technical consumers.

There’s little chance that high-end wineries will abandon barrels and make all their wines in TCA-free tanks; there’s no choice for fine wine production equivalent to the rise of synthetics and screwcaps. But this controversy is likely to mean that wineries will be asking their barrel suppliers about more than simply toast level and forest geography from now on.

Tim Patterson is the author of the newly released Home Winemaking for Dummies. He writes about wine and makes his own in Berkeley, Calif. Years of experience as a journalist, combined with a contrarian streak, make him interested in getting to the bottom of wine stories, casting a critical eye on conventional wisdom in the process.

Posted on 01.05.2011 - 13:18:12 PST
One note: At Taransaud we check for TBA in the containers, not TCA.
Mel Knox
San Francisco, CA USA

Posted on 01.15.2011 - 16:00:43 PST
The Taransaud point out that they also test containers for TCA. And I may even said that. But I meant to say that they test for TBA.

Too many initials.

Mel Knox
San Francisco, CA USA