Élaboration du vin et hygiène

[Don Max]

Voici un article intéressant sur lequel je suis tombé lors mes nombreuses recherches sur le déviations aromatiques dans le vin. On peut se rendre compte à la lecture de l'importance de l'hygiène dans les espaces servant à la vinification et à l'élevage. Il est aussi intéressant de lire comment la sensibilité au TCA peut varier entre dégustateurs et comment la perception peut varier, chez un même dégustateur, selon le profil aromatique du vin. L'exemple du Château Montelana qui est décrit dans ce texte montre bien tout le flou que peuvent induire les contaminations à concentrations se rapprochant du seuil général de détection. Dépendant des molécules impliquées, certains en détectent la présence, d'autre pas. Certains sont dérangés, d'autres pas. Voilà une zone grise qui forcément ne peut faire l'unanimité.

Don Max




Chateau Montelena Battles "Cellar Funk"

Posted: Wednesday, August 25, 2004

By James Laube



Chateau Montelena in Napa Valley has undertaken a major renovation of its cellar after discovering that both the winery and its wines have been contaminated by TCA (2,4,6 trichloranisole), a chemical compound responsible for the off-flavors in corky wines.

Winemaker Bo Barrett said Chateau Montelena, best known for its Cabernet Sauvignons and Chardonnays, began testing its facility for a possible TCA problem in 2002. Recent vintages had repeatedly shown a musty character, he said, which the winery believed came from TCA-tainted corks.

But after a Wine Spectator report in 2002 detailed how Beaulieu Vineyard's red-wine cellar had been tainted by TCA, Barrett said, Chateau Montelena hired a leading wine laboratory to test its cellar, equipment and wines. ETS Laboratories, based in St. Helena, Calif., determined the presence of TCA. "Then we realized it wasn't the cork thing," Barrett said.

Barrett admitted that it is likely that TCA was part of the winery's "house style" and that it was present in most of the wines at a low level. TCA "may have been one of the components of our wines dating back to the 1970s," he said, "especially when the wines weren't fruity."

TCA can form when mold interacts with chlorine and phenolic compounds in products such as wood, cardboard or cork; if it's not detected, it can spread throughout a winery, into barrels and wines. While TCA may impart a musty or moldy character to wines, or simply mute their fruit character, it is not a health threat.

Chateau Montelena produces 40,000 cases a year, and the Montelena Estate Cabernet bottling sells for $125 a bottle. Barrett declined to say how many of the wines had been tested by ETS. But he said early tests showed some of the wines had TCA levels near 4 parts per trillion (ppt), and the winery has been trying to bring the level down to 1.4 ppt or less in its latest vintages.

There is no industry-wide standard for an acceptable level of TCA in wines, and people's ability to detect TCA varies greatly. The 1.4 ppt level is considered below the threshold of perception for most tasters, though sensitive individuals can detect even lower concentrations.

Barrett acknowledged that the winery was battling TCA after Wine Spectator showed him lab tests done this summer that indicated some Chateau Montelena Cabernets, including the 2001 and 1997 Montelena Estate bottlings, had low levels of TCA.

Symptoms of TCA taint were first detected in blind tastings in the magazine's Napa office. Many Chateau Montelena wines, from the 1997 vintage to a 2003 barrel sample, showed either wet cement and chalky, chlorinelike flavors or other off-characteristics associated with TCA. So Wine Spectator had ETS Laboratories test seven Montelena Cabernet samples; five of them had levels of TCA ranging from 1.1 ppt to 1.7 ppt, and two had less than 1 ppt.

The ETS test results also found that all seven of the samples had low levels of tetrachloroanisole and pentachloroanisole, compounds which are similar to TCA and are associated with wood treated with certain preservatives; such chemically treated wood has been linked to taint problems in many European cellars.

Chateau Montelena had already begun overhauling its old cellar immediately after ETS confirmed the existence of TCA, though Barrett declined to estimate how much the cleanup has cost. He said the winery had replaced all suspect barrels and old cooperage, along with all wood barrel racks that had come in contact with chlorine in cleaning agents. The winery's interior walls were hand-scraped to remove accumulations, and wood catwalks and ladders were replaced with aluminum. The winery has been replacing oak fermentation and storage tanks, changing out 17,000 gallons of tanks in 2003 and 2004, he said.

Keeping Montelena's cellar clean has been a challenge, because the building is old, dating to the 1870s, and chlorine-based products had been used for years to clean the interior. Barrett said the winery had a "cellar funk" to it, and over the decades, he and his staff have battled microbial issues related to Brettanomyces, a spoilage yeast, along with bad corks.

Montelena is the latest California winery to have its wines marked by TCA. BV's tainted red wines dated to 1997 and may have involved several hundred-thousand cases; the winery has since revamped its entire cellar. Wine Spectator also discovered TCA contamination at Hanzell, a Chardonnay and Pinot Noir specialist in Sonoma, and Gallo of Sonoma, one of Sonoma's largest wineries. Hanzell has since opened new wine production and storage areas. And in an ongoing process, Gallo has made changes at its Dry Creek Valley facility that it reports have reduced TCA levels in the cellar and the wines so far.

[Caudalie]

Wow, bien intéressant....

Ca veut donc dire qu'effectivement, on pourrait trouver des vins bouchés avec une capsule à vis ayant des caractéristiques de vins bouchonnés... en raison de TCA dans les installations...

Merci bien Don max

[Don Max]

Salut Caudalie,

Pour plus de détails encore, regarde ce lien de Wikipédia à la section "Systemic TCA".

Don Max



http://en.wikipedia.org/wiki/Cork_taint

[Don Max]

Par rapport au TCA, j'ai eu une expérience intéressante cette semaine. Je parlais de vin avec un collègue de travail. Oui, oui, un autre vilain chimiste! Il me disait avoir ouvert une bouteille de vin blanc bouchonnée la veille et avoir remarqué des taches vertes le long de petites fissures sur le mirroir du bouchon. Le lendemain, il a amené la bouteille au boulot, avant de la retourner à la SAQ. Le vin était bel et bien bouchonné et comme il me l'avait décrit, il y avait des taches vertes, dans de petites fissures sur le mirroir. Ça ressemblait vraiment à des colonies microbiologiques. Finalement, j'ai vu que le vin était un Chardonnay du Jura, 2004, de Stéphane Tissot. La robe était très foncée, signe d'oxydation du vin. Tissot, parmi bien des choses, est un adepte de l'usage minimal de sulfites dans ses vins. Je n'ai pu faire autrement que me demander si colonies microbiennes ou levuriennes suspectées seraient apparues si le vin avait reçu une dose plus courante de sulfites, et donc, si le vin, dans ces conditions aurait été bouchonné? Il faut savoir que le TCA dans les bouchons provient du métabolisme de microorganismes, bactérie, levure ou champignon. Bien sûr, ce n'est qu'une hypothèse de ma part, Toutefois, elle est basée sur des observations et sur la théorie que j'ai pu lire sur le sujet. Pas de "hard science" là, donc....

Don Max

[Don Max]

Chile's Viña Errázuriz Confronts Contaminated Cellar
Problem with TBA may be widespread in Chile and Argentina

James Molesworth
Posted: Friday, February 09, 2007


A Chilean winery has joined the unfortunate ranks of wine producers in France and California who are battling contamination in their wine cellars, as it works to eliminate a rogue chemical that imparts musty, dry flavors to wines.

Viña Errázuriz, a well-established and highly regarded winery located in the Aconcagua Valley, has admitted that some of its wines contain elevated levels of TBA (2,4,6-tribromoanisole), a nearly identical compound to the more familiar TCA (2,4,6-trichloroanisole), which is known for causing cork taint in wines. Both compounds result in dry, musty odors in wines. Many wineries in France and some in California have spent the last decade dealing with the effects of TCA-related contamination in their cellars, and experts and other winemakers worry that the TBA problem may be spreading in Chile and Argentina.

TBA is typically derived from wood preservatives and flame-retardant paints used in cellar construction. The compound can then spread through a winery; porous materials like plastic hoses are particularly susceptible. TBA has become a problem for wineries in South America because the locally produced materials used to build their cellars contain bromophenols, which can create TBA. (In contrast, the building materials used by French wineries in the 1980s and '90s commonly contained chlorophenols, which can evolve into tetrachloroanisole and pentachloroanisole, which are similar to TCA. Those materials have since been banned.)

"[TBA] is a big problem in Chile and Argentina right now," said Pascal Chatonnet, a Bordeaux-based enologist who consults extensively in both countries. Chatonnet is one of the world's leading experts on TCA and TBA contamination; he is credited with isolating and identifying the cause of TBA after research he conducted in 2004. One of his earlier studies showed that TCA and TBA can be transmitted through the air.

The problem at Errázuriz first came to light when some of its wines repeatedly showed musty, dry flavors in Wine Spectator blind tastings. Subsequent tests conducted by ETS Laboratories in Napa Valley confirmed the presence of TBA in the Viña Errázuriz The Blend Limited Edition Aconcagua Valley 2004, an 800-case lot blend of Cabernet Sauvignon, Syrah, Carmenère, Petit Verdot and Sangiovese. The wine sells for $40 per bottle. ETS measured the presence of TBA at a level of 4.5 parts per trillion (ppt), higher than the 4 ppt considered to be the normal threshold for detection for that compound, according to Chatonnet. There are no health risks to drinking wine tainted by TBA or TCA.

Eduardo Chadwick, owner of Viña Errázuriz, admitted that his winery has had a TBA problem, and said that he is working to correct it. "We had some old wood sectors in the cellar that were potentially giving out TBA," Chadwick said. "We know The Blend is one wine that was bottled with an amount of TBA that could be considered above the normal percentage. Since the 2005 vintage however, we are confident that the wines are now totally clean."

Errazuriz winemaker Francisco Baettig is now checking for TBA every step of the way.
Chadwick said he has replaced all the old wood in his underground cellar in Panquehue, replaced all plastic hoses with rubber ones and installed an air circulation system (since stale air can exacerbate taint problems). The winery has also instituted a series of quality checks that test for TBA in each lot of wine through each stage of the vinification and aging process, in addition to testing for TCA and brettanomyces, a spoilage yeast that results in overtly gamy aromas.

Viña Errázuriz winemaker Francisco Baettig noticed the potential for taint soon after joining the winery in 2003. "I realized we could have problems since we used wooden chocks and logs to stack the barrels," said Baettig. "We started to take samples from all kinds of materials in early 2004, and we realized we had some level of contamination. When we checked the wines, we realized that the contamination level was increasing from [vintage] 2002 onward."

The hard part was pinpointing the source of the contamination, Chadwick said. "TBA can be in a single hose, or on some barrel bungs, making it very difficult to find. But once you know what it is and where it is, then it can be dealt with fairly easily."

Identifying TBA as the type of taint has also been difficult for Chilean wineries, as the molecule is so similar to TCA, the more commonly known source of musty odors in wine. According to Eric Herve, a scientist with ETS Laboratories in California, TBA and TCA are "virtually identical" molecules, with the exception that "TBA has bromine atoms where TCA has chlorine atoms."

Chatonnet explained that while many South American wineries realized there was a problem when their wines began to show musty notes, they were testing for TCA instead of realizing they had a different culprit on their hands. (Chatonnet would not disclose the wineries for which he is working.)

"Organoleptically it is very difficult to tell the difference. They are both musty," Chatonnet said. "There is a little more bitterness prevalent on the palate with TBA, but the threshold is also a little higher than TCA--4 parts per trillion for TBA versus 2 to 3 parts per trillion for TCA."

But TBA contamination is a particularly serious problem for infected wineries, since it indicates a problem with the winery facility itself, as opposed to flawed corks or closures on which TCA developed. (In tainted California cellars, the problem is not typically linked to the building materials but to the use of chlorine-based cleaning products, which react with plant-based phenols such as those in corks, to form TCA.)

"TBA wouldn't originate from the cork," said Herve. "Cork can be a vector, if the corks were stored in a TBA-contaminated room. But its presence [in a wine] is more likely a factor of widespread airborne contamination."

Chatonnet agreed. "If TBA is in a wine, it means the winery is probably contaminated."

Consultant Aurelio Montes says a growing number of wineries are seeking advice on cellar taint.
Viña Errázuriz is only the latest example of TBA rearing its ugly head in Chile. Viña Santa Laura recalled 300 cases of its 2001 Cabernet Sauvignon Colchagua Valley Laura Hartwig after owner Alejandro Hartwig Jr. began finding samples that exhibited musty, dusty notes, which were attributed to TBA.

"TBA didn't kill me, so I hope it made me stronger," said Hartwig. "I lost a lot of business thanks to that. When you don't know where it's coming from, it's especially frustrating and expensive to deal with. Once I figured out it was coming from the wood beams that separated my barrels, I got underway with solving the problem."

Aurelio Montes, one of Chile's most respected winemakers and consultants, who also works in Argentina, said he has been fielding an increasing number of calls from wineries looking for his help with potential TBA problems. "It's a growing problem," asserted Montes, who also speaks from personal experience. "I started seeing some strange flavors in my own wines three years ago. And after testing, the problem was TBA--not TCA--which was something totally new to us."

Montes said the wines, which were being aged at his older winery facility in Apalta, were from one vintage and in a select number of barrels. To deal with the problem, Montes did not release the wines into the market, threw away the offending barrels and installed an automatic ventilation system that moves 10 times the total air volume in the winery each day.

"We didn't want a problem with our wine in the marketplace--so we dealt with it before they got to market," Montes said. "It takes a pile of money to get rid of [TBA]--and it's a very difficult decision to make, especially if you're a small winery. But you have to make that decision."

Montes also noted that sometimes winemakers have trouble detecting TBA taint problems because they become used to the aroma after working in an infected area for so long.

Other top consultants who work extensively in South America--Paul Hobbs and Alberto Antonini--also said they had faced problems with TBA. "Unfortunately, I've had to deal with this first-hand on several occasions," said Antonini. "I'm now very strict with my clients when it comes to this subject, and I force them to get rid of all the potential sources of contamination. Sometimes the producer doesn't want to do it because it is an expensive decision to make. [But] it is a lot cheaper than damaging your brand."

"The message is there, in capital letters, in red and underlined," said Montes. "You have to attack it--there can be no half measures."


http://www.winespectator.com/Wine/Featu ... 35,00.html