THE MARRIAGE OF WINE AND WOOD
Since ancient times, oak barrels have been used to create essential flavour compounds
Most wine drinkers are aware that oak barrels are used in the aging and fermentation process, but how oak impacts wine and the flavours it imparts is often another matter. There was a time, as early as 10,000 BC, when wine was no more than smashedup grapes allowed to ferment in clay amphoras naturally, and some natural wines are still made this way (hence the chunky bits in the bottles).
The use of oak is thought to have been introduced by the Romans around 400 BC, most likely to transport the essential beverage during times of war and trade. The barrels were much easier to transport and sturdier than clay amphora, but understanding how the vessels could impact flavour didn't come until sometime in the 17th century in Europe.
The skill itself, the craft of soaking, heating, and bending wooden staves, is known as coopering and was likely a byproduct of shipbuilding. Archeologists uncovered a fully intact ship in the Great Pyramid of Giza that dates to 2500 BC, and it demonstrated the early stages of constructing vessels out of wooden staves.
Technology has changed the world in ways we could never imagine yet the craft of coopering has remained relatively unchanged save for the inclusion of power tools.
Electing to age your wine in oak barrels is a costly investment these days as a new French oak barrel will run you about $1,800 a pop, and about $600 less for American oak. A standard 225-litre barrel yields approximately 300 bottles of wine, which means if you are a medium-sized winery producing upwards of 50,000, 12-bottle cases a year, the investment is considerable.
French oak is desirable because it imparts subtle flavours like vanilla, spice, nuts and even herbs. American oak tends to be more obvious, adding elements of coconut, cocoa, smoke, and sweet vanilla. It also has two to four times as many lactones (wood esters) than its French counterpart.
The style of wine you want to make plays an important role in barrel selection. For example, robust, fruit-forward styles of wine like Zinfandel and Australian shiraz are typical candidates for American oak whereas Bordeaux, Napa Cabernet and Burgundy are better suited to French. French oak (Quercus Robur) is physiologically different than its American counterpart (Quercus Alba) in that it's more open-grained and must be split by hand.
It starts with the wood being milled into staves and then dried, either in a kiln or, preferably, by air, and up to three years in some instances. The inside of completed barrels are toasted to varying degrees based on the customer's needs. A light toast will impart sweet and creamy characteristics and is typically employed for white wines while a medium toast will impart bolder, smoky flavours, along with spice, vanilla, nut, and yeasty notes. Heavily toasted barrels are typically used for fortified wines and spirits as the flavours would overwhelm most wines. White wines can also be fermented in oak barrels (reds can as well although it's rare) which can add depth and texture to the wine, but there's a risk of overwhelming the wine with wood flavours.
The great British wine writer Hugh Johnson has stated that if oak is obvious in wine, it's excessive, and I tend to agree. When handled with a deft touch, it adds an intriguing component to wine, and the barrel itself does a great job of harmonizing flavours, but can easily dominate a wine's taste profile, especially with white wines. Over time it's become a tool for winemakers to mask the flaws in what would otherwise be a thin and unremarkable wine. California ran with the ball back in the '80s with brands like J. Lohr Seven Oaks and Rombauer that offered oak in spades, the quintessential “buttery” style of Chardonnay that still exists to this day, although many producers have backed off on the amount used.
Fermenting and aging wine in barrels is an expensive undertaking, so winemakers look to affordable alternatives such as oak chips, staves, and oak essence. These additives are used far more commonly than most of us are aware of, but the odds are if you are tasting oak flavours in an inexpensive wine, you are tasting oak flavouring of some description. I've always maintained that if you want to really taste what a great Chardonnay can offer, try a bottle of good Chablis. Oak is rarely used in Chablis, except for some of the pricey Grand Cru examples and, as such, the wine has nowhere to hide. In a good vintage, the wine offers loads of minerality along with a complex array of citrus flavours. If you get a buttery characteristic, it's typically a result of malolactic fermentation, the conversion of malic acid to lactic acid. For this to happen, the wine may be seeded with the required bacteria or by allowing a natural source of the bacteria (uninoculated) to take over.
Red wines can handle more oak without it dominating but it's always worthwhile tasting reds that have gone from stainless steel tank to bottle, sans barrel. Beaujolais is a great example as the fruity, zesty red wine would lose its charm and character in the presence of wood flavours. Bardolino, a blend of corvina, rondinella and molinara grapes from Italy's Veneto region, is another good example. Serve it lightly chilled in the summer with a simple tomato salad and some grilled bread, lightly drizzled with good olive oil and a little sea salt, a classic example of less being more.
Oak barrels do have a life after their initial voyage, however, as used barrels provide a great vessel for the integration of flavour compounds. Second-fill barrels can still impart some oakiness but much less of it, ideal in many cases. Beyond that, if they're well maintained, they can be used for many years, as is common with many German Rieslings. Puncheons and demi-muids, which hold 500 litres and 600 litres respectively, can be used for decades in some cases.
Understanding what oak contributes to wine is one of the least understood components of wine appreciation among consumers, and as such it's worthy of exploration, from the naked to full-blown California butter bomb, vive la difference. Cheers! Geoff Last is a longtime Calgary wine merchant writer, instructor, and broadcaster. He can be heard every Friday on CJSW'S Road Pops program between 4 -6 p.m. He was awarded a fellowship at Napa Valley's Symposium of Professional Wine Writers for articles that have appeared in this column.
Media inquiries can be directed to lastcallforwine@gmail.com