A song to the oak, the brave old oak,
Who hath ruled in the greenwood long;
Here’s health and renown to his broad green crown,
And his fifty arms so strong.
There’s fear in his frown when the Sun goes down,
And the fire in the West fades out;
And he showeth his might on a wild midnight,
When the storms through his branches shout.
— Henry Fothergill Chorley
“The Brave Old Oak”
Fashion comes and fashion goes in winemaking as in life. Hank Chorley got it right though, because oak has ruled for a very long time. The use of oak in the right amount can turn a merely average wine into a prize-winner. The delicate scent of vanilla, toastiness and smoke enhances the fruit flavors and aromas already present, forming a complex bouquet. Beyond adding aromas it can also be a more subtle enhancer, lending structure, tannin and balance to otherwise simple wines. Oak can also do yeoman work covering up flaws, reducing green or vegetal character in under-ripe wines. A small dose can lend a wine maturity and character.
On the other hand, the inappropriate or heavy-handed use of oak can damage wine, sometimes beyond repair. An oak overdose can take so many years of aging to mellow that the wine passes from fickle youth, through maturity, to feeble old age before the flavors are softened enough to make it drinkable. Anyone who has ever drank an over-oaked wine will recognize the flavors and aromas of “Chateau Plywood” immediately.
Traditionally, only full-bodied red wines and richly-flavored whites like Chardonnays — and occasionally Sauvignon Blancs — are treated with oak. Floral or more delicate wines aren’t helped by oak, the coy charm of these subtle wines becomes lost in the blast of smoke, toast and vanilla.
Unfortunately, some time back in the mid-to-late 1980’s a certain winemaking nation full of kangaroos and poisonous fur-covered ducks discovered a niche for bookcase-flavored wines and went absolutely nuts with the oak. Because the wines released were in a very good price-point and aggressively marketed, they garnered a lot of fans who drank splintery Chardonnay and sawdust Shiraz, and loved it.
Today the pendulum has swung back, at least a little, with unoaked (sometimes sold as “unwooded”) versions of popular wines being seen, and even the Aussies have pulled way back from the bad old days of woodshop winemaking.
Many factors influence the type of oak and the method of application in wine. Forward-thinking commercial wineries try to achieve an oak flavor profile that is appropriate to the wine description, without overwhelming it. After all, their goal is for you to be able to enjoy the wine more or less immediately, come back, and give them more money for another bottle — so expect the oak character to be mellow as opposed to brutish.
And you too can customize your wine to your taste. Some people prefer a hearty wallop of oak character, especially in New-World style Chardonnay or California Cabernet Sauvignon. For these sylvanophiles, a little extra oak can go a long way.
First Things First: Oak Barrels
The traditional image of the winemaking cellar is of the cellar master, his face lined with the wisdom of experience, drawing a crimson stream of wine from his massive, sturdy oak barrel. Behind him, row after row of barrels sleep with their precious contents growing more potent, rich and valuable with each passing year, phenols slowly seeping from the wood into the wine, making vanilla magic in the cool dark.
Part of the unseen influence of oak barrel aging lies not only with this ability to impart wood flavors and aromas, but also from a process called elevage. This includes a plethora of biological and chemical reactions between oak and wood, the most important of which causes water and alcohol to evaporate from the wine in roughly equal measure. It varies by local humidity, oak type and barrel size and construction, but can amount to 6.0 gallons (23 L) from a standard 60-gallon (227-L) barrel in a single year. This concentrates the remaining wine, intensifying all of its flavors. This also makes it necessary to top up the barrel periodically to prevent the ullage (airspace) from oxidizing the remaining wine.
It’s all a very pretty picture, but the truth is that between the cost of the barrel itself (some premium French oak barrels can go for $2,000+ each) and the 10% loss of yield per year, it can be tough for some winemakers to go the barrel route. Some fine wineries don’t use any barrels at all, relying on processed oak products to add wood character to their wines instead.
As a home winemaker, you don’t need to use barrels either. There are a whole host of oak-alternative products out there which will lend toast, spice and vanilla flavors to your wine, stabilize color in
reds, reduce green tannins and enhance mouthfeel, all without putting a barrel in the dining room.
Lumbering Through the Forest
All of the oak used in alternative products is derived from the same sources as those used in traditional barrels: oak trees from France, Eastern Europe and the United States. Selected trees are harvested, sawn or split and dried, either in the open air or in special kilns. (Those dried in the open air are more expensive.) They are then typically allowed to “season” for several years. During this time, the naturally-occurring tannins mellow and become less aggressive. The wood is then cleaned up and processed. (For an detailed account of oak and barrel manufacture, see Frank J. Lipski’s article, “Building Barrels” in the February-March 2004 issue of WineMaker.)
Trying to make a judgement on the character of your oak is a tough game: few oak products are labeled with the specific forest they were grown in, and the minutiae of Limousin versus Nevers and Missouri versus Oregon is mind-numbing and really only applies to barrel construction due to details of grain tightness and growth rings. (Limousin and Nevers are places in central France that are home to the most famous oak orchards. American oak largely comes from the US states of Missouri and Oregon.)
As a very general rule of thumb to guide your oak choices, American oak products will have a more aggressive character, more vanilla, tannin and “woodiness” than their French counterparts, which are smoother and perhaps a bit more delicate. New American oak barrels also cost roughly half that of new French oak barrels.
The Grind: Chunks, Chips, Sticks, Powder, Cubes and Staves.
Processed oak comes in five main forms: powder, shavings, chips, cubes (sometimes called “beans”) and sticks or staves. They are available with a dark, light, or medium toast and you can sometimes choose between the woods of different countries and regions. They can be split into two categories, pre-fermentation and post-fermentation use, with a little overlap in between.
Powder and shavings (and sometimes beans and chips) are commonly added prior to fermentation. This allows the yeast to react to and modify the tannins and aromas of the oak. The yeast actually transforms the more intense oak compounds into less aromatic ones, making the oak smoother and less aggressive. In addition, fermenting with oak encourages the formation of polysaccharides, a type of very complex sugar, which adds weight to the wine and increases mouthfeel and the perception of length on the wines finish.
Staves and sticks (and sometimes beans and chips) are added post-fermentation. While pre-fermentation oak is mellower, post-fermentation oak is another ball of wax. Instead of being transformed by yeast action, the oak aromatics and flavor compounds are simply extracted from the wood by the alcohol (almost all of the compounds are alcohol soluble as opposed to water-soluble). Without the influence of the yeast the aroma and flavor profile is much more aggressive and more tannic, and the level of toasting shows through to a greater degree.
Oak That’s All Wet
The one form you’ll want to avoid is the liquid underbelly of the oak alternatives, oak extract. It really is the instant coffee of the genre, complete with stale and unpleasant character. The only thing it really offers is instant gratification, and if you fall for its thin charms, the next thing you know you’ll be eating spray-cheese from a can and buying scratch-off lottery tickets. Just say no.
There’s no doubt oak extract is the most convenient way to get oak flavor and aroma in wine. Made by soaking oak chunks or chips in high-proof alcohol, all you do is add a measured amount of the liquid to your finished wine and stir. The trouble is that the flavor is harsh, with a “burnt” nose and not a lot of fresh, toasty oak. This is partly due to the high alcohol content of the extraction medium (neutral ethanol) and partly because nobody has seriously developed a high-quality shelf-stable version.
This isn’t to say there’s no place for extracts in winemaking. This is how big wineries add a touch-up of oak to their wines, by infusing a portion of the wine in with a huge dose of oak powder (imagine using a snow shovel to add oak to your carboy). After the oak flavors and aromas have been extracted, they filter the oak base wine and run trials to see how much they need to blend in to the main batch to hit the right character. Neat, easy, and they don’t run the risk of over-oaking the entire batch.
While it’s possible for home winemakers to make their own extract and use it in the same way, it’s usually just as easy to add oak directly to your carboys — keep in mind that the oaked base-wine isn’t good for anything else if you have any left over, unless you know of any beavers who like to drink.
Jammin’ on Toastin’
A note on toast levels: all oak products are toasted to a greater or lesser degree, usually in natural gas or oak-fired ovens. Although natural gas is easier to control, oak-firing gives and extra layer of smoky complexity, which replicates the way barrels are traditionally toasted, over an open fire. This toasting is very rigorously controlled to produce a variety of flavors and aromas. In fact, it can be fine-tuned to make oak products with high levels of vanillin, tannin, 5-methyl furfural (a chemical that lends a sugary-creamy character that is very nice in Chardonnay) or even guaiacol (smoke). How about that, smoke has a science-name!
Choose a specific toast level to complement each wine. Usually light toasts go into whites, dark toasts into heavy reds. Sometimes a blend of lighter and darker toasts is used, to give both sweet vanilla notes and a layer of smokiness.
Quercus Pulvis: Taking a Powder
Looking like little more than sawdust, oak powder is a convenient and easy way to get oak flavor and aroma into your wine. The nicest thing about the powder is that it’s so convenient; throw it in and ignore it. When you rack your wine, almost all the powder gets left behind in the bottom of the carboy. You get oak flavor, and no fuss.
One of the other nice things about powder is the high surface-area-to-mass ratio. Because the powder exposes so much surface area your wine will extract almost all of the flavor from it within a very short time: often less than 48 hours! That’s why it can be added to the primary and racked away from in less than a week — its work is done almost immediately.
Quercus Fragmentus: Shavings and Chips
Made by pushing pieces of oak through a planer or a chipper, shavings and chips are in many respects similar to oak powder: no fuss or maintenance — oak flavor without the investment and worry of a barrel. Aside from the shape (shavings look either like curls from a plane, or like woody shredded wheat, while the chips look like the byproduct of a clumsy wood chisel session), the main difference lies in when you choose to use them, pre or post fermentation. While they don’t have the extreme surface-area-to-mass ratio of powder, chips and shavings still have a high enough level to release virtually all of their character within a week or so of immersion in the wine.
Quercus Virga/Legumen/Ferula: Beans, Sticks and Staves
Beans, sticks and staves deliver the same yummy-toasty oak goodness in different configurations, making them either easier or harder to handle, depending on your point of view. The sticks are straight sections of oak staves, usually less than a foot long and looking a lot like paint-stirring sticks that spent too much time in the oven. They can be simply plunged into a carboy and allowed to soak and sink, and some of them even come with little holes drilled into each end, so that they can be strung together and hauled out as a piece. Staves are the same thing, only in Jolly Green Giant size, and often look like a barrel stave that left home to seek its fortune. They operate in the same way as sticks, but more slowly due to higher mass-to-surface-area ratio.
Oak beans are interesting: on the surface, these little cubes perform much as any other chunked or chipped oak material. However, due to their uniformity of size, they can actually be subjected to graduated toasting: that is, they can be toasted on one side to a depth of a little less than 3⁄8ths of an inch (a few millimeters), with the remaining oak cooked, but not darkened. Manufacturers claim that this configuration gives a more natural “barrel-like” experience, since barrels are only toasted to a shallow depth, and wine penetrates well beyond this.
Of course, this toasted/untoasted effect can be replicated by using a mixture of light and dark toasted oak products of any kind, so it might not be an exclusive advantage, but it really is a neat trick.
The much lower surface-to-mass ratio of these products means that they take longer to release their oak character, often over the course of several months. This makes them attractive as a “touch-up” oak, to increase the oak profile of a wine gradually. They can be added to a carboy and the wine can be checked at regular intervals to see if it’s hit the right level of oakiness, when they can be removed.
The Bottom of the Barrel
A note on handling oak products: they are all packed in a completely sanitary manner. There is no need to boil them, or soak them in a sulfite solution or cook them in the microwave. Oak and other nicely- grained woods have a fascinating property of being able to maintain their sanitary character, as long as they are kept dry. The capillaries in the wood act like miniature bacterial dehydrators, killing off potential spoilage organisms. Store them cool and dry, and pitch them straight into the wine. If they do get damp, you can either poach them in boiling water, dry and microwave them on high for one or two minutes, or simply toss them out to be on the safe side.
Some people like to put their oak into a sock or a muslin sack or a nylon stocking (new, please!) in order to make it easier to retrieve and discard. This only works in an open primary fermenter — sure you can stuff a knee-high nylon full of oak chips through the neck of your carboy, but try getting it back out after the wood has had a chance to swell! The oak floating in suspension can be a bit tricky, clogging your racking tube when you go to siphon. You can get a bit of muslin or some such and tie it over the end of the racking tube, but that’s tricky as well. The best solution is to simply wait until the fermentation has subsided. This will allow the oak powder or chips to settle out where they won’t affect your racking cane.
If you are intent on a more aggressive oak profile, start slow: rather than add a lot of extra oak powder or chips to the primary fermentation, start with half the amount you expect to use, and after your batch is finished primary fermentation (and substantially de-gassed!) add more oak to the carboy. The oak you choose will depend on the type of wine and the style that you are trying to emulate.
If you were trying to make a big oaky California Zinfandel, you would want heavy toast American chips. If you are aiming for a delicate Pinot Noir, you’ll want medium toast French chips, and so on. If you want more advice on choosing the type of oak best suited to your wine, ask the people who sold you your grapes, juice or kit or check out what experience other winemakers have had with oaking schemes.
Start slow, with perhaps an extra half-ounce per 6.0 gallons (14 grams per 23 liters). You can always add more oak later but over-oaking is like over-salting the stew: there’s definitely a diminishing return! Check the wine on a regular basis: every other day or so. If you suddenly find it approaching too much oakiness, you can rack the wine away from the oak, or yank the sticks out of the carboy, and rest easy knowing that a month or two of aging will mellow it down.
This article really only scratches the surface of the role of oak in winemaking. In addition to the flavor effects that oak has on wine, and the biochemical changes it induces, the whole history of winemaking — and indeed the history of wine in civilization — is intertwined inseparably with wood. From the barrels used to age and transport it, to the trees the ancient Greeks used to train their vines along and every post and stake used today, wood and wine have gone together. So the next time you’re enjoying a pleasantly oaky Chardonnay or a rich, smoky Zinfandel, remember the brave old oak that helped make the wine in your glass.
Tim Vandergrift is Technical Services Manager for Winexpert and WineMaker’s regular kit columnist. He once experimented with oaking his wine with Norwegian Wood, but woke up in a bathtub. He blogs mercilessly at www.timswineblog.com.