Are French Barrels Corking Your Wine?

Study finds significant levels of TCA in barrels; French Federation of Coopers calls foul and alleges conflict of interest
Oct 6, 2010

Are those months of respite in French oak actually unhealthy for your wine? A controversial new study conducted by researchers at Lab Excell in Bordeaux, led by Dr. Pascal Chatonnet, posits that barrels can be a significant source of 2,4,6-trichloroanisole (TCA), the compound behind "corked" wines. The study, published in the Journal of Agriculture and Food Chemistry, says the problem is growing. But French barrel makers are crying foul, accusing Chatonnet of self-serving findings.

TCA is the leading cause of cork taint, the dirty, musty taste wine drinkers associate with defective corks. But it can also develop when certain compounds come into contact with wood products used in the winemaking process, such as barrels.

In some Lab Excell tests, the team found that very localized incidences of TCA—as little as 5 percent of a barrel’s inside surface area—could ruin the whole volume of wine. Chatonnet, who believes that the “barrel taint” problem is a recent one limited to French cooperages, is pessimistic that the problem can be fixed until the source of the contamination is ascertained, something Excell has been unable to do. “The problem is increasing because we don’t know exactly what the origin is," he said. "So until we will be able to identify clearly the most important origin of TCA on the [barrel] stave, there is no reason for a decrease in the problem.”

Some have found the motives of the Excell research suspicious because the lab has also patented a procedure to check barrels for TCA at the cooperage, flushing them with a mixture of hot water and alcohol and then testing the mixture for TCA levels. Critics point to an e-mail memo Chatonnet has sent to multiple wineries both explaining his findings and offering his services. The diagnostic test costs between $5 and $15 per barrel.

The Federation of French Coopers, whose members produce more than 95 percent of the wine barrels in France and include respected tonnelleries such as Francois Frère, Seguin Moreau, Taransaud, Radoux, Saury and Vicard, has accused Lab Excell of bearing a problem in one hand and a solution in the other. “This publication is [aimed at] the wineries,” said Philippe Rapacz, Federation president and CEO of Seguin Moreau. “It says, ‘Look, there is a risk, maybe. But don’t worry, guys. I have a solution. I have my patent, if you just pay a couple of bucks, for each barrel of course. And then I can guarantee that your barrels are not contaminated.’ Really? Really?”

According to Rapacz, the Federation has worked vigilantly since 2002 to screen barrels for TCA, in tandem with several French labs. (In a case of tainted love, Lab Excell was among the Federation’s partner institutes.) The group's technical commission has developed guidelines to minimize the infiltration of TCA into barrels, including auditing the wood supplier, testing the water used for seasoning the barrels at least three times a year, inspecting the containers and packages the barrels are transported in and even checking the oil in their machinery for chemicals that might lead to TCA.

The guidelines are unenforced and perhaps unenforceable across France’s many cooperages, but the Federation collects statistics of TCA incidences from its constituents every year. The percentage has remained steady at about 0.03 percent for the last three years, or 100 barrels out of France’s annual production of 550,000. “When [Chatonnet] says that we don’t take care of this problem, that is wrong,” said Rapacz. “We are very upset about this.”

But Chatonnet’s paper paints a different picture. “The extent of this problem is still severely underestimated by coopers and barrel-users, due to the extremely unpredictable, localized contamination of the staves,” the text reads. Chatonnet's team studied about 10 wineries and five cooperages during a five-year period. “I think we have maybe 0.15, 0.25 percent of the barrels with problems detected,” he said. “But I think that 100 percent of barrels are [at risk].” Chatonnet said small wineries are especially vulnerable, as five tainted barrels could ruin a “micro-cuvée” aging in 10 or 20 barrels total. In larger wineries, he said, it is unlikely that barrel-tainted wines would reach the consumer’s table or cellar but could create a headache for winemakers forced to throw a batch out because of a flawed barrel.

Rapacz agreed and cited this as proof that the current quality-control methods have been adequate. “When you have a problem of TCA—and it happens, it happens—I can guarantee to you that the [wineries] react very quickly and very tough," he said. "The first guys who are going to react are not Mr. Chatonnet. It’s our customers.”

Chatonnet counters that the greater TCA threat may be on the horizon. “It’s like the same situation with corks 15 or 20 years ago,” he said. “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.”

Both interests acknowledge that the cause of TCA formation in barrels is unknown. Chatonnet believes the problem is a new and spreading one, possibly linked to the large amount of wood collected in the aftermath of Europe’s major storms of 1999; Excell is planning follow-up studies about the provenance of the taint.

Wine Flaws TCA Winery Taint France News

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