The Institute of Masters of Wine, in conjunction with Christie's Wine Department and Taransaud Tonnellerie, examined the sensitive and compelling subject of oak use in winemaking during a four-hour seminar entitled "Oak: Crucial and Controversial" in June 2005. Orchestrated over a year and a half, the impeccably run, comprehensive tasting featured top industry insiders. Anthony Hanson, Master of Wine and senior consultant to Christie's International Wine Department, moderated the panel of experts.

Five tastings delineated discussion points. All products of the 2004 vintage, the samples of unfinished French and American wines were aged in specially crafted 30-liter (eight-gallon) Taransaud barrels, with the exception of David Ramey's Chardonnays, the first tasting of the day.

Tasting 1:
Fermentation—Steel vs. New Oak and Used Oak

Understanding the interaction of wine, oak and lees enables Ramey to create a well-rounded package for his consumers. Since grapes taste different every year, these trials help him understand how best to showcase them. He can vinify in oak or stainless steel, use new or old barrels and employ different types of oak to achieve different taste profiles. "Wine is preserved fruit. I pick at the point where the fruit is most delicious. These grapes were picked at 23.7 Brix," he said. What occurs post-picking is clearly vital as the three resulting wines were strikingly different.

The wine aged in stainless steel presented the least aroma, with only delicate grapefruit and grass scents emerging. This wine boasted the most acidity, but the resulting sensation was not particularly pleasing. Moving on, Stephan von Neipperg, owner of several French wineries, noted the wine from the second-fill barrel, coopered by Louis Latour, seemed "most Burgundian." Indeed, the barrel imparted lactic, cheesy qualities on the nose and a mellowed, yet still defined acidity that melded to form an attractive whole. By contrast, the wine aged in a new, Francois Frères-coopered barrel exhibited overt oak on the nose and palate. Pronounced almond essence denoted the leaching of furfural (sweet smelling) components from the barrel.

Preferring the wines aged in oak, Ramey said, "The import of phenolic material into the wines as well as the exchange of oxidation creates wines I prefer." The wine from the new oak barrel topped his charts. "This offers the most complete mouth feel of all the wines. It seems more like a finished wine than any of the others."

Ramey's comment concluded a very basic but informative starting point. The panel acknowledged that while the oak barrels each received 24 months' natural aging outside and medium-plus toast, they were sourced from two different coopers, adding a potential variable in results. However, all agreed that this factor was insignificant because the variation in barrel age—regardless of the cooper—consistently produces similar results.

Tasting 2:
Origin of Oak—
France, Europe, USA

Displaying tart lemon-lime characteristics and very light body and color, the reference wine was mercifully intended to be nothing more. The sharp, grassy finish resulted in an unpleasant aftertaste. The French oak was well integrated, allowing floral notes to shine through while providing a smooth mouth feel. Hints of butter nodded to oak aging as did flavors of rich fall fruits, such as pear and apple. The American oak produced a wildly fragrant nose bursting with dill. Also boasting a smooth palate, the more lusty flavors of caramel and baking spice also pointed directly to the oak's American origins. The wine aged in Polish oak proved disjointed. Its alcohol seemed magnified compared to the other wines, and a touch of aggressive acidity at the back of the palate hinted at volatile acidity. The long finish did offer attractive nuances of caramel and spice; however, the tactile awkwardness of the wine proved disconcerting. Nonetheless, many tasters could clearly discern Polish oak's most readily identifiable trait: cardamom.

The reds, from Château La Lagune, received the same oak treatment as the whites. Here, however, the tannin element blurred some of the individuality of the oaks. The tannins proved most moderate on the American oak wine while the French and Polish showed more, though not unpleasant, astringency and structure. European oak, be it Polish, Hungarian or Russian, offers nuances similar to French Sessile oak (see commentary in Tasting 3).

Interestingly, the alcohol proved more prominent on the Polish oak-aged wines for both white and red experiments. Many participants mistook the French for the Polish oak and vice versa, but the American oak proved hard to miss with its distinctive dill and cucumber overtones. However, the wine with American oak treatment won few compliments. Michael Silacci, winemaker at Opus One, declared the wine "the harshest," and von Neipperg slowly constructed a "PC" statement: "I cannot understand it, but perhaps in time I will come to learn it. I find American oak can be interesting for certain wines."

So how does a winemaker know if he's getting the oak he ordered? "You don't," said Ramey flatly. "You have to entirely trust your cooper because you can't tell by looking from where the oak originates." While you can visually differentiate tight from wide grain, as well as toasting level, there is simply no way to count fibers or observe grain patterns to determine provenance.

Tasting 3:
French Oak Regions—Tronçais, Vosges, Centre

Sampling from barrels (aged outside for 24 months with medium toasting), tasters tackled with delight four glasses (one a stainless steel "reference" wine) of Corton Charlemagne Grand Cru from Bouchard Père et Fils. The climates of the oak aligned precisely with their origin. Sources further north afforded more structure and less overt oak influence. More temperate climates evoked more oak expression. The Tronçais oak showed greener tones and brighter acidity while sporting the lightest body. The Vosges oak also provided solid structure as well as agreeable spicy notes of pear and apple fruit. The Centre sample resulted in leaner, green apple fruit than the Vosges but still turned out the most overt oak overtones on the palate and finish. Of the three, Centre oak came closest to American, with its milky undertones and cinnamon spice, but the lack of coconut or dill and the ultra-smooth palate would have steered any discerning blind taster toward the eastern side of the Atlantic.

Did the panel's winemakers find a compelling difference between the three varieties? "There is no difference in the analysis of the different barrels," said Silacci. "Actually, there is, but it's only nuance." Ramey concurred, "The results are inconsequential." He did point out, however, that all of the wines aged in French oak up to that point provided a much smoother palate than did the American oak-aged wine from Tasting 2. Ramey also offered a few other markers for determining oak source: intense smoke and clove prove most common in French oak while vanillin is more pronounced in American oak.

Tasting 4:
Influence of Open-Air Seasoning Duration

Seasoning stabilizes wood so that it can be formed into barrels. That means the moisture content of freshly split wood must drop from 55 percent to 15 percent. Coopers procure such a dramatic decrease in three ways: A kiln dryer, which extracts moisture through the circulation of hot air through an enclosed space; a combination of kiln dryer and natural exposure; or 100 percent natural-air seasoning.

Wood for the highest quality barrels comes from 100 percent natural-air seasoning. This method takes the longest because the wood actually takes on moisture from rain, fog, snow and other precipitation during the process. Seasoning at approximately one centimeter per year, coopers usually wait three-to-four years for the material to reach its prime state. "Prime" is the point at which the wood loses all of its gross tannins. Because of stocking large amounts of wood well in advance of use and special palletizing requirements, this method is extremely expensive. The reward, however, is the contribution of elegant spice and richness to the wines. Kiln drying is more economical and allows coopers to rush big orders, but their use can "bake in" green tannins, which impart bitterness and astringency.

Samples of Château La Lagune from oak aged outside for 24, 12 and six months proved insightful. (Note: all wines were aged in these barrels for the same period of time. The aging variation only applies to open-air seasoning prior to the barrel's construction.) Astringency and tannins followed a bell curve. At the peak of the curve, Silacci said the 12-month-seasoned wine showed the "leanest and driest of samples." Oak aroma and flavor also showed most noticeably on this wine. Surprisingly, instead of showing harsh, green notes, the six-month-aged sample imparted soft tannin and little astringency. At the far end of the chart, the 24-month-aged oak sample offered the smoothest mouth feel, with a more pronounced character than the six-month-aged wine.

The seminar then reverted to refreshing whites, scrutinizing the same outside seasoning effects on the Sauvignon Blanc of Château Malartic Lagravière. Puzzling even to the winemakers, the 12-month-aged wine again showed the most pronounced oak. The bell curve held consistent here, with the six-month-aged sample withdrawn and showing little fruit, and the 24-month-aged sample proving well-rounded with mineral and waxy notes and a smooth, long finish. Ramey declared the 24-month-aged wine a good sample and proposed tasting the same wines in another 12 months to look for better potential integration.

Tasting 5:
Toasting Level

• Light or Medium-Minus
• Medium
• Medium-Plus
• Heavy or Strong
• Intensive Toast or Grande Chauffe

Light toasting is achieved when the wood temperature reaches 120-180° C (248-356°F), and the wood begins to soften. After 10 minutes, the staves' surface temperature reaches 200°C (390°F) and qualifies for medium toast. Another five minutes ratchets the surface temperature to 225°C (437°F) as the staves receive a heavy toast.

During the toasting process, wood structure degrades and transforms into aromatic compounds. Wood tannins soften and disappear as the heat index rises, and smoke and clove notes become more pronounced. At the highest toast levels, however, aromatic compounds begin to disappear. Long, soft toasting produces the most aromatic barrels. Finally, the length of toasting, not the intensity alone, contributes to the roundness and length of finish barrels can impart.

Four samples each of a Sauvignon/Semillon blend from Domaine de Chevalier in Pessac-Léognan and a Merlot from Château d'Aiguilhe in Côtes de Castillon composed the final tasting. The reference wine received only stainless steel aging while the three others absorbed "raw," medium and heavy toast. As with all levels of toast, different coopers have different standards for "raw." In Taransaud terminology, raw wood is heated only enough to bend the staves into shape.

In both trials, the heavy toast barrels resulted in the most complex wines. The reds showed no color differential; the whites showed deepening yellows with increased toasting. Jean-Pierre Giraud commented, "When you have no toast, you have no link between the wine and the wood." David Ramey concurred, "The untoasted oak has a coarse, short effect on the palate." The white wine aged in raw oak tasted of bitter nuts on the finish while the red exhibited green pyrazine flavors. No classic oak aroma or flavor characteristics were evident, though tactile sensations were. The medium toast red showed just as much tannin as the raw, but the wine was less drying. At the medium level, notes of vanilla, caramel, cream and clove surfaced in the white.

In sum, while the raw and medium wines seemed somewhat incomplete, the heavy toast combined the most appealing aroma and tactile qualities of the first two and raised them to a much higher level. Interestingly, a winemaker in the audience pointed out that most French barrels have non-toasted heads. "So, you're getting the benefit of complexity right in the same barrel," concluded Hanson.

As the tasting wrapped-up, Ramey gave the group a wise reminder: "Winemaking is like a film, and the wines we are looking at are snapshots in time." With the possible exception of some of the whites, few of the wines tasted would be commercially available at such a young stage of their development. While their youth permits the study of the effects of variations on oak, drawing anything more than tentative conclusions on the taste profile of a finished wine could rule out some commercially viable styles. The oak effects were clearly exaggerated by the wines' age as well as the small size of barrels used. Milliliter per milliliter, the wines would not have absorbed as much oak in more standard operating procedures.

Covering 31 wines over the course of the afternoon, a more comprehensive tasting is hard to imagine. Were a few more glasses added to the crowded tables, a study across oak alternatives, such as staves and powder, would have proved another interesting comparison. However, as the brief discussion on alternatives pointed out, oak substitutes, even when supplemented by micro-oxygenation, simply cannot produce the benefit of slow oxygenation that barrels provide.

While the official commentary was unfolding, hushed whispers and muttered declarations among the trade in the audience revealed deep, dividing lines on oak treatment. New or Old World, light or heavy toast, under-oaked or under-wined, the conflicting messages from the heart of the conference room pointed precisely to the intrigue of oak use in wine: differing opinions and room for them all. wbm

Toasting develops aromas. Both the intensity of and the duration over the flame contribute to the overall sensory experience. The classic scale is:

Taransaud's Jean-Pierre Giraud introduced this tasting. He indicated that when oak is not properly seasoned, the wood's green tannins can show up in a wine. Not only does the seasoning length play a determinant, so does the method in which the wood is seasoned. A tip to those buying barrels on a budget: If you choose less expensive, shorter-aged oak, splurge on heavier toast, which can cover up the wood's shortcomings to a degree.

Oaks grown for barrelmaking come from north, east and central France. Oak from the cooler northern and eastern areas typically belongs to the Sessile family and possesses more complexity. Oak from the north-central Allier forest tends to the spicier side while oak from the Tronçais forest is known for offering a refined mouth feel. Pedunculate oak from the south-central Centre region of Limousin is more aggressive, quickly adding vanillin notes and deepening color.

Trials were conducted on both whites and reds. First, four variations on Sauvignon Blanc from Château Malartic Lagravière in Graves, Bordeaux, were presented blind: a stainless steel wine for reference and three samples aged in French, European (Polish) and American oak. All wood received 24 months' outside aging and medium toast. From a poll of the room after this tasting, the oak treatment of the whites was evidently easier to identify as follows:

In his Hyde Vineyard (Carneros) Chardonnay experiment, Ramey Wine Cellars winemaker David Ramey compared the effects of fermentation and aging in new oak, second-use oak and stainless steel barrels. Ramey also looked at the effect of lees aging and stirring, and noted that "yeast still do things even though they are dead."