Wine and Oak
by Jason Harris
Oak often contributes significant flavor to wine. Finding the right oak character for the wine variety can truly raise the complexity and flavor to the next level. Historically this combination of wood and oak occurred as vintners used barrels as the most economical way to store their wine. While it is no longer a matter of economy, the tradition of aging wine in oak barrels has become an integral part of many vintners winemaking techniques.
Keystone Homebrew offers home vintners many options on adding oak to their wine. Before using any oaking technique you should first evaluate the style of wine you are making and determine if oak is an appropriate additive. Consider your own personal taste preferences as well. Next, find the right species of white oak, with few exceptions, the only kind of wood used in winemaking barrels. The most commonly used oaks are American white oak (Quercus alba) and French oak (Quercus petrae Liebl), known for their soft tannins. Other oak used in barrel making comes from Hungry, Slovenia, and Portugal. Finally, determine what oak product to use. Options include oak barrels, soakers, cubes, chips, powder, and oak essence. Each product can be compared by cost, ease of use, amount of wine needed, time until result is achieved, and replication of barrel effects.
The most genuine oaking method is aging wine in a barrel. Owning a barrel is like owning a pet: it requires attention and care or things can go very wrong. The best way to keep your barrel in good condition is to keep it full of wine. Barrels that have too much ullage (air space) can be ruined along with your wine by the effects of microorganisms including mold, vinegar bacteria, and the effects of oxidation. Before being used, a barrel needs to be filled with water to make sure the wood swells and that there are no leaks. If, after being used, a barrel is going to be stored empty it is imperative that a sulphur source is burned inside to prevent the growth of microorganisms. As a source of oak flavor, the useful lifespan of a barrel is considered to be 4 fills, after which time most of the oak essence has been extracted from the wood. This “neutral” barrel can still be used to store bulk wine. Please note that if a barrel is contaminated by mold, vinegar bacteria or other spoilage organisms, it should never be used for wine again. This is because a barrel contains numerous nooks and crannies where these organisms can hide and getting rid of them is impossible.
Let’s start the comparison with the real deal, a 225L (60 gal., cost: $350-$1200) oak barrel; this is the most common barrel size used by commercial wineries worldwide. This size barrel seems to have the best surface to volume ratio for extracting the oak essence while reducing the effects of evaporation during aging. In order to utilize a barrel this size a winemaker must be committed to at least 60-70 gallons of one type of wine each year.
When winemakers use smaller barrels in the 5 to 30 gallon range, they have to take into consideration that the wine will only be able to spend a short period of time in the barrel. The high oak surface to wine volume ratio in small barrels increases the amount of oak tannin in the wine and also the amount of evaporation. One to three months is probably the longest you want to keep a wine in a new 5 or 6 gallon barrel. As the barrels get older and the remaining oak essence is reduced, longer aging may be possible. Nevertheless, the winemaker must stay vigilant and keep the barrel filled to prevent spoilage caused by too much evaporation. To use a small barrel, a winemaker should be committed to making six to ten batches a year, rotating the wines so that each batch gets only a short stay in the barrel. Oak barrels range from about $100 (2 gal.) to $400 (30 gal.).
Oak cubes and soakers are generally added to a wine after the primary fermentation and are allowed to soak in the wine; 1 ounce per 5 gallons for one month is typical. Oak soakers are toasted using a procedure that imitates the oak character of barrels: the outside edges are heavily toasted while the inside remains lightly toasted. This enables the soakers to contribute both the dark and light toasted oak flavors to maximize complexity. The soakers also have the added benefit of being easy to add and remove because of their spherical shape.
Oak chips are the least expensive way to add oak to wine. One ounce per 5 gallons for one month is typical. Unless you have an extremely discerning palate, these chips may provide an oakiness equivalent to the soakers or cubes.
Another fast method is oak powder, also called Oak mor, which is ground to the consistency of saw dust in order to quickly impart oak flavor. It is commonly found in wine kits and with time will settle out of wine in the fermenter. Multiple ounces are often added to wine allowing an even shorter contact time. At Keystone we do not favor the use of these products for several reasons: first, it is often impossible to determine the origin of what is essentially sawdust. Even though one can say the same thing about other forms of oak, the image of sawdust being swept up off a mill’s floor is disconcerting. Second, finely milled oak has a tremendous surface area, which, if not carefully monitored can lead to over-extraction of oak essences.
Last on the list of oak products is oak essence, commercially known as Sinatin 17. Oak essence is an extract of oak that can be added directly to the wine. This procedure can be done at the last minute before bottling. Using oak essence in wine is like using liquid smoke in cooking: you can get a good end result, but is it the same? Oak essence can also be difficult to control and once added, removal can be very difficult
Additional information on oak barrels and oaking your wine can be found in the comprehensive book Techniques in Home Winemaking, by Daniel Pambianchi.