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To Oak or Not To Oak

by David on April 1, 2010

In the early part of this century you may have noticed a movement toward low oak and no-oak Chardonnays and other whites. It’s not a surprising response to complaints about what have been called the over-oaked wines of the 1990s, those from the new world particular.

If the trend is to play down the oak character it takes us back to fundamentals: why do we barrel age the wine? These days, if oak flavor is the only goal we can save a lot of money and time by using oak chips or installing oak staves in tanks rather than buying barrels. And, given that a 60-gallon French oak barrel is over $1000.00 now, with the weak dollar, there has to be more to consider than just flavor addition.

The birth of the barrel
We believe that the ancient practice of hollowing out trees to build boats gave birth to the idea of bending wood to make barrels. By around 350 B.C. the Celts refined their building techniques to produce a container that was water-tight, could bear the weight of stacking and withstand the stress of being rolled around. It very much resembled barrels, as we know them, today. For over 2000 years the wooden barrel changed very little and was the sturdiest vessel available for shipping oil, grain, salt, pickles, even wine.

It’s hard to find any specific turning point but, apparently, the practice of aging wine goes back to the ancients. Before barrels were used, wine was stored in large, two-handled clay containers called amphorae. The Romans were known as great appreciators of aged wines and aged it in the amphorae, and later in wooden containers of various description including some that were called cupa. They even simulated aging by heating or smoking the wine in some cases. A contemporary of Julius Caesar wrote that wine was so valuable that Italian merchants could trade one amphora-full for one slave!

These cupa were probably larger than today’s standard wine barrel, but that’s the term that was eventually adopted for barrels. It’s not hard to imagine that ancient names such as the Latin cupa, French cupals and German kufers, were the origin of today’s word, cooper, for a barrel builder.

Wine quality fell with the fall of the Roman Empire

For the most part, the fall of the Roman empire meant the fall of both quality and quantity of wine, too, and the taste for aged wine seemed to disappear for nearly 1000 years. The church was the main thing that kept wine production alive at all, during those dark years, until the Renaissance brought about a renewed interest in wine. And, as it regained popularity, quality improved. By the end of the 18th century, in Bordeaux, the unwieldy wooden tonneau, which held 100 cases and was used for both aging and shipping was being replaced by the modern barrique, or 25-case barrel as we know it.

The taste for aged wine came roaring back with the introduction of the glass bottle with cork stopper in the 1600s. By the 1800s the bottles were of uniform-enough shape to push the cork all the way into the neck which created the need for the first corkscrews. The ability to bottle-age wine also led to the practice of vintage dating it so the consumer could keep track of what was in his cellar.

The wine business may have been dormant for all that time, the barrel-building business thrived through the centuries. That is, until a few coopers began to hang up their tools as the mechanization of barrel building began eliminating jobs in the late 1800s. Even more of them turned to other crafts when the 20th century introduced new, lightweight options for transport. As the century went on, increasingly wine, beer and spirits were bottled at the production facility rather than being shipped out in barrels. By now, the wine and spirits industry are almost the only remaining customers for today’s coopers and the sole purpose of barrels is aging.

Barrels as flavoring agents

It appears that barrels were relied upon for aging and storage, but not for flavoring wine until relatively recently, perhaps around the late 1960s, in Bordeaux. In fact, certain oak species were preferred for their neutrality of flavor and lack of bitterness, compared to other woods of similar holding capacity. Jancis Robinson places the emphasis on using a high percentage of new barrels in Bordeaux at around the 1980s and, of course, the trend traveled around the world rather quickly.

In California, we aged and stored most of the wine in redwood or concrete tanks until stainless steel and small cooperage came into the picture. Hanzell Vineyards in Sonoma is credited as the first California winery to use French oak to age their wine in the 1950s. They were followed by Heitz Cellars in the 60s.

Robert Mondavi came on strong with an extensive barrel research program that looked at regional barrel styles, oak sources and production methods. This new love affair with barrels is probably why it became fashionable to make the oak character so prominent. Being able to say “we use 100% new French oak” became a status symbol for some wineries and there are even those who boast about using 200% new oak, which means that the wine goes into a new barrel twice during barrel aging instead of staying in the same old barrel! There are wines with great enough concentration to balance the impact of new barrels but, in some cases, the oak flavor takes center stage. Since wine appreciation is completely subjective there are, and will always be, fans of the oaky style. But, it seems that somewhere around the turn of this century many of us began to become tired of these heavily-oaked wines.

Effects beyond oak flavor

Why would the winemaker use barrels if he doesn’t want the oak flavor? It’s almost like magic. We’ve known for a very long time that the wine becomes softer and more integrated with barrel time, even if we didn’t know why. There is much that we still don’t understand, but it boils down to very slow aeration, which causes maturation.

The wood is porous and wineries experience more or less evaporation loss, at least a few bottles per barrel each year, depending on the degree of humidity in the cellar. The loss is called the “angel’s share”. The aeration sets off a whole chain of chemical reactions that change color, aroma, flavor and texture. For instance, a newly-fermented Cabernet looks very much like Welch’s grape juice and also tastes awfully grapey. As it ages in the barrel the color evolves toward the ruby hue we’re accustomed to, and the flavors become more wine like as they evolve beyond primary fruit characteristics and gain complexity. The aeration softens the tannin and a wine that initially felt clumsy on the palate gains finesse. The evaporation loss concentrates the wine a bit, too.

Oddly enough, additional aeration is caused by a technique called topping, which is designed to protect the wine from excess oxidation and spoilage. Wineries top their barrels to replace the angel’s share, anywhere from twice a week, to every few months to never, depending on the amount of labor they’re willing to dedicate. Of course, each time the stopper, which is called the bung, is removed it exposes the wine to more air, so it’s hard to calculate what’s accomplished, all told. But, these are the most compelling reasons to barrel age the wine and flavor addition is a more recent preoccupation.

On a very practical note, the aeration in barrel aids in clarification by way of encouraging the residual grape solids and dead yeast cells to settle, nicely, in the bowl-like bilge at the bottom of the barrel. Then, the winemaker can easily siphon the clear wine off the top and move it into another container, a procedure called racking. Of course, racking exposes the wine to oxygen, too. It’s the slowest and most labor-intensive way of clarifying the wine, but many would argue the best and most natural.

Larger cooperage and alternatives to barrel aging

As mentioned, we’ve noticed a pull-back on oak flavor, especially for Chardonnay, in recent years and even no-oak Chardonnays and other whites. In fact, coopers have remarked that they’re selling more large containers, recently, which is an interesting return to the past and also a great way to tone down the oak.

For centuries many of the classic European wine-producing regions aged their wines in oak containers considerably larger than the 60-gallon standard of today. Beautiful oval casks can be seen in a number German and Italian wineries and large wooden tanks, almost anywhere. The larger the volume, the slower the aeration, and there’s less wine to wood contact so little or no oak flavor extraction. This seems to be making a comeback when producers of complex whites want the benefit of aging, but a subtle impact on flavor.

Up to very recently, there was no way to get the effect of barrel aging, other than to make the investment and do the work. And, there are those who insist that there is still no good replacement for barrel aging, but in the 1990s, the French introduced a technique they call microbullage, and we call micro-oxygenation. The inspiration came from the desire to soften some extremely tannic wines made in the south of France. Micro-ox, as they like to call it, allows the winemaker to introduce precise amounts of oxygen at any stage of winemaking depending upon the desired effect. For instance, some extra oxygen during fermentation can help to keep the yeast healthy although there are low-tech methods that accomplish the same thing. Micro-ox during aging helps encourage the suspended solids to settle nicely, so it moves clarification along and may even help the winemaker avoid filtration if that’s his goal. It also seems to offset green character that may exist due to under-ripe grapes.

Importantly, for low-end producers, micro-ox can mimic the effect of barrel aging right inside a tank, especially when used along with oak chips or inserted oak staves. When the winemaker chooses to use chips or staves he can select the forest, species of oak and the toasting level, just as he can when purchasing barrels. Not only does this save the cost of the barrel, it saves a great deal in labor, since the winemaker racks, tastes or analyzes a few batches of a large quantity instead of numerous smaller batches. And, in stainless steel, topping is unnecessary.

Why oak?

So, why is it always oak? In times past, if the barrel was meant for dry goods, usually the cheapest suitable soft wood was used, like fir and pine. For liquids it’s important to select a tree that has a tight enough grain not to leak and yet, for aging wine, beer or spirits enough porosity for aeration. It needs the physical strength to hold a great deal of weight and also durability for moving and shipping. Over the centuries dozens of different woods have been used, especially chestnut, but when you put flavor into the equation, oak seems to be the best timber to satisfy all the requirements. Many of the woods were coated with paraffin to block unpleasant flavor absorption but they minimized aeration at the same time. Oak was the closest thing they could find to neutrality of flavor.

And then there’s the choice of oak, for instance the odd, angular growth pattern makes the California Live Oak very beautiful, but unsuitable for barrels. Of the 250 different types of oak in the world, essentially, only three are commonly used in barrel making these days.

Oak species

American and French oak are not the same species, which is important to the cooper. Because of differences in physical properties he gets more barrels per log from American oak and there are flavor differences. Generally speaking, we find that American oak is stronger in aromatics and flavor than French and that the French oak lends the wine a little more structure. Like wine grapes, where it grows makes a difference. Eastern European oak, for instance, has gained popularity recently. It’s the same species as the French, but the growing conditions alter its personality toward more nutty and vanilla. It seems to be a good choice when the winemaker is looking for fruit-forward character. As of 2008, French oak barrels are approaching $1200.00 each, American are around $375.00 and Eastern European oak coming in around the middle.

So far, most coopers don’t seem to be terribly concerned about the potential impact of oak substitutes and micro-ox on their industry. In fact, they indicate that the sales of French oak cooperage are on the rise. We don’t have data on the long-term effects of micro-ox so we don’t know how wines subjected to this treatment will do over the long haul. Also, there are those who say that the difference between oak substitutes and oak-aged wine can be tasted. Barrel brokers surmise that the high-end producers aren’t moving away from barrel aging because they’ve spent so much on the grapes, and put so much care into the process, that they don’t dare risk anything that might compromise quality.

That’s where we are now. It would be interesting to fast-forward 100 years to see if the craft of coopering still exists and what other innovations have taken place in our ever-changing world of wine. In the meantime, enjoy your Chardonnay – oaked or otherwise.

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