Aside from grapes themselves, nothing influences the aroma and flavor of wine as much as oak barrels. The toasty aromas of Chardonnay, much of the spice found in Zinfandel, and clearly the cedar and tobacco notes in a fine Cabernet Sauvignon derive from oak wine barrels. Fine wine and oak barrels have historically been perfect marriage partners for centuries-barrels define tradition. In fact no other symbol so succinctly represents the mystery and quality of fine wine as the oak barrel.

Modern-day commerce has changed the regal wine barrel. Today's custom barrels are no longer produced by crusty, bow-legged coopers relying on years of tradition and experience. Today's coopers have embraced new technologies and years of chemical analysis, and have blended them with their long tradition and are now producing the most refined, specialized, specific products the wine industry has ever seen.

Today's coopers tend to agree on several facts: the oak species plays a big part in selecting barrels; the wood should be aged a minimum of 18-24 months; grain types are a prime influence in the reaction between wine and barrel; and the toasting method and level of toast influence the barrel's effect on the wine more than any other factor.

Alain Fouquet is a fourth-generation Maitre Tonnellier, with 40 years' experience as a cooper, and owns Alain Fouquet French Cooperage in Napa. Although he prides himself on tradition, he stays very up-to-date on research. "The cooper is at the service of the winemaker, but we must teach them. Winemakers used to think the wood breathed; wood doesn't breathe. There's a chemical reaction between the wine and the wood. That chemical reaction creates the aromas and flavors."

For winemakers, purchasing barrels no longer involves something as prosaic as simply selecting forests and toast levels. Today, winemakers can consult with research directors who study the chemical reactions between wood and wine, and measure the results and print colorful charts explaining what all the research means. They can design their own barrel-making methodology to provide specific aroma, flavor and tannic profiles. They can tailor-make their barrels to fit a grape varietal or even a specific vineyard.

Wine-Specific Barrels

Most recently, several companies have combined their research with selected specific wood types and modified technology to develop barrels designed especially for white wines.

David Llodrá, director of research and development at World Cooperage in Napa, claims that his company pioneered the research that led to developing different barrel treatments, beginning in 2000. "We developed a system called Barrel Profiling to monitor and follow aromatics and tannin levels throughout the toasting process. We can control the humidity of the staves, airflow, time and temperature. Then we quadruplicate the results in tastings with chemical analysis to verify our results. We have 80 different barrel profiles in our World Cooperage line. We also have a Cotes d'Or barrel in our T.W. Boswell line, which is designed for white wine."

Barrel profiling uses the latest sensors, a computer network and touch-screen monitoring to toast every barrel. The cooper simply inputs a barrel's wood specifications and desired toasting profile, then the computer directs the cooper to increase, decrease or maintain the barrel's current temperature to follow the desired profile.

Typically, World Cooperage asks a winemaker which varietal he is working with and to define his style. They present three or four toasting profiles to best achieve that goal. Winemakers must purchase a minimum of four barrels in each profile. After experimenting with the barrels, winemakers can adjust temperatures, grain types and toast levels to hone in on exact aroma and flavor components.

George Bursick, winemaker for Ferrari Carano Winery in Sonoma, has used the Cotes d'Or barrels for three years. "I went to the plant in Missouri and physically ran the system. It works. At certain temperatures you get different compounds, and they've been able to determine which temperatures give which compounds; and because of their computer system, they get repeatability. Every barrel run on your program comes out with the same flavors."

Bursick made minor changes in the barrel profile of his Cotes d'Or barrels, and these custom barrels were tagged "Big Bad Bursick" barrels by his cellar crew. Bursick uses the new barrels exclusively for Chardonnay although second-year barrels receive Sauvignon Blanc. "I buy the barrels primarily for their first-year influence. The barrels give elegant, integrated aromas and flavors of soft caramel with no coarseness in the finish."

Tonnellerie Radoux, located in Santa Rosa, California, is another cooperage that has been experimenting with specialized white wine barrels, beginning in 2001 when they worked with four wineries in the Languedoc Roussillon area. The trials focused on Chardonnay and Sauvignon Blanc. (Excel laboratory handled the specific chemical analyses in relation to the contribution of the barrels.) Radoux also used sensory analysis to judge the effects of the barrels on the wine.

Nicolas Mähler-Besse, director of marketing for Radoux, said, "If possible, we don't sell our barrels without knowing what type of wine is going inside and what style the winemaker hopes to achieve." Radoux's research points to the prime importance of wood grain to the finished barrel. Their research indicates that tighter grain wood gives more aromas and less tannin along with slower extraction. Medium grain wood gives more tannic structure, less intense aroma and quicker extraction.

Their research also focused on the toasting of the wood. They begin with a pre-toast, using water and heat to create suppleness in the wood. Next is the actual toasting, which involves a constant and slow heating. The final stage is the bousinage, which incorporates a lid over the barrel to concentrate temperatures. It is this temperature spike that gives the barrel the majority of its aroma profile. Radoux's Classique barrels use a short, intense bousinage while their Evolution barrels lower the maximum temperature and extend the length of bousinage. Radoux monitors temperatures during toasting with an infrared pyrometer with laser sighting and records the results to set up a database.

Their white wine barrel, Selection Vin Blanc, actually blends 50 percent tight-grain wood and 50 percent medium-grain wood. They do a medium toast using the Evolution method. Winemakers do have the ability to customize their barrels by changing grains, bousinage or toasting, to the point where Radoux claims to have 800 different choices. The Selection Vin Blanc barrel is available for sale in the United States this year.

Stephane Nadalié, of Napa's Nadalié USA, is more secretive about his process. He has created two Perle Blanche barrels: one emphasizes fruit character, the other brings out spice character. The barrels are created using two different proprietary blends of oak, blends that for now are a well-kept secret. Perle Blanche barrels, designed for the fruity component, use medium toast while barrels designed for the spice component use medium + toast.

Ken Deis, winemaker for Flora Springs Winery in St. Helena, started experimenting with Perle Blanche barrels in 2004. Deis has had a long-standing relationship with the Nadalié family and agreed to work with Stephane in evaluating the barrels. "The first year we worked with both barrels," he explained, "and in the beginning we all preferred the fruity barrel. But by the end of our seven-month trial we switched our preference to the spicy barrel. I suppose our grapes have so much inherent fruit character that the added spice makes it more interesting."

Philippe Michel, who owns the new Oak Tradition company in Santa Rosa, represents several barrel-makers. From the Tonnellerie du Sud Oeste comes a unique white wine barrel made from acacia wood, robinia pseudoacacia to be exact. This acacia barrel is made from medium grain wood with medium or medium + toast. "It helps bring out floral aromas in white wine along with a more refined complexity and softer tannins than oak," said Michel.

Gary Horner from Erath Winery in Dundee, Oregon, has experimented with a couple of the acacia barrels. He put Pinot Gris into the new barrels and discovered a dominant "honey" note. "It's an interesting component," he said. "A little goes a long way, and I mean that in a very positive sense." The second year Horner tried Riesling in the barrels. "Once again, we got the honey character; and just two barrels gave the blend a subtle but obvious concentration."

Mel Knox, who sells Francois Freres and Taransaud barrels, among others, is a bit skeptical, however, about the merits of barrel profiling. "I think varietal barrels are more of a cooper's gimmick. I prefer to let my customers choose which regimes regarding forests and toast levels are best for their wines." He agrees that grain width is important and points out that it is a function of species as well as location. Knox also points out that most burgundies go into barrels unfiltered to undergo malolactic in the barrel, which slows the intensity of extraction. This is evidently crucial to white wine development in barrels. In fact, every barrel representative mentioned in this article recommends having lees in the barrels and then stirring those lees to slow the extraction from the barrel.

Jeff Murrell, director of research for StaVin, a Sausalito, California-based company that produces handcrafted, toasted oak integration products, also feels that these unique barrels may be overrated. "I think that varietal-specific barrels are more marketing than actual reality. Winemakers have their own vision and notion of style for their wines." StaVin makes barrel alternatives.

StaVin oak beans are created by cutting toasted oak staves. Because the beans are smaller and release quicker extraction, winemakers can perform trials on their wines. They can check Hungarian, American and French oak with convection toasting or fire toasting in either medium, medium + or heavy toast levels. Based on those trial results, StaVin can then design programs with the winemakers specific to the wines in question, as can other providers of oak alternatives such as Sonoma, California-based Innerstave.

With oak alternatives the slower the extraction, the more gentle and married into the wine is the oak component.

Evaluating a New Generation of Barrels

Whether you are using oak barrels or barrel alternatives, the aging and toasting of the wood are critical. Several molecules exist in freshly cut wood. Cis G-Octa Lactone is the dominant aroma of rough timber and smells of coconut. Vanillin expresses vanilla aroma. Eugenol gives the aroma of cloves. Ellagitannins are the tannins found naturally in the wood. Except for ellagitannins, aging raw wood appears to concentrate these aroma molecules. Toasting almost doubles the concentration. (Ellagitannins actually reduce when the wood is aged, and the longer the wood is toasted the more these ellagitannins are reduced.)

Of course, measuring these compounds as they develop in the wood aging or toasting process is one thing, translating that information into actual winemaking is another. Some sensory work has been done using a five-point scale, but that's not exactly based on formal sensory models. Something as simple as different alcohol levels from one vintage to another could have a major influence on these aroma compounds and their interaction with one another. Winemakers will have to bring their own expert tasting ability to bear when evaluating this new generation of barrels.

If winemakers buy into the current research, then they need to forget about forests and focus on grain. Tight grain gives more aromas, less tannin and slower extraction. Medium grain gives fewer aromas but more tannic structure. Younger wood is more aromatic but also harsher. Winemakers can no longer rely on toast level, but must determine actual temperature and methodology; both influence which aroma and flavor molecules will develop.

When it comes to technology that allows winemakers to tailor-make barrels to elicit the exact aromas and flavors they want, coopers have different ideas about specifics, and they call their techniques by different names. They measure the chemical reactions in different ways, and they talk about working with winemakers to give them the exact flavors they want. But the bottom line is that it's all up to the winemaker.

It is true that winemakers are opinionated-every one of them has a different idea of what is right. While coopers claim they have the technology to customize barrels to fit each winemaker's needs, the ability of the cooper and winemaker to communicate with one another will determine the success of these specialized barrels. Over the next few years consumers will taste for themselves the flavors favored by different winemakers. Ultimately they will decide who's right.

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New York Oak Barrels Used to Create Greater Sense of Terroir

When Chris Stamp, winemaker at Lakewood Vineyards in Watkins Glen, New York, thought about how to get a greater sense of terroir in his New York wines, he turned to his barrel program. Although he was happy with his mix of French and American oak, he wondered if a New York oak program would work.

"When you are talking about terroir and then putting it in a French oak barrel, it's just not the same. It's not terroir that you're adding there," said Stamp. "If we want these things to speak of their origins, we can't do that with barrels from 3,000 miles away."

Stamp worked for Pennsylvania-based Keystone Cooperage, a barrel manufacturer that sources wood from the Appalachian region of the U.S. Lakewood Vintners had already been using Keystone Cooperage for their American oak needs, but the barrels did not have a specific regional designation. Stamp approached the cooperage, and they are now separately tempering the New York wood to use in the program. The staves are seasoned for three years.

"This has been a long time coming," said Stamp. "It's too soon to tell right now how it will work, though. I think it's going to be next year when they will really tell their story-and hopefully that story will be a good one. We try to use oak with an average age of two or three years old so the staves aren't too overpowering or too neutral. These first-year barrels are part of the whole scheme. It's going to be three years of evaluating before we can get a really good story on them."wbm

Lance Cutler  

quelle: www.winebusiness.com