ONE of the most important factors on wine quality, after the grape juice itself, is the proper use of oak in wine aging. Describing wine with lovely bouquet, tobacco flavors, and long vanilla-like finish is not possible without the influence of oak aging. Wine develops flavors and complexity when aged in oak barrels.

The use of barrels in wine started centuries ago, but more as storage and as transport vessels for the precious wine, rather than for its flavor enhancement qualities. It was just in the late 18^th century that the role of oak barrels in wine aging was truly established.

Barrels come in different sizes, ranging from over 2,400-liter capacity in the case of traditional extra-large cask called botti used in Italy’s Piedmont region, to smaller ones like a 100-liter Hungarian barrel. Standardization of barrel-size eventually took place in the late 19^th century, specifically in 1880s, when the French Bordeaux model of 225-liter barrel was made the “de facto” size and remains at present the most common barrel size used for aging wine.

These wine barrels are crafted from white oak trees found in France, eastern European countries like Croatia (specifically in region of Slavonia), Hungary and Romania, and the US, particularly from the state of Missouri. The companies making wine barrels are known as cooperage or in French as tonnellerie.

There are major considerations to look at in oak aging:

• The Grape Varietal — Oak aging can used for both red and white grape varietals depending on the style and intention of the winemaker. Most red varietals, from Cabernet Sauvignon, Syrah, Zinfandel, Merlot, to Pinot Noir, are very oak-friendly and benefit a lot from ample oak aging. On the other hand, other red varietals similar to Gamay (Beaujolais, France) and Dolcetto (Piedmont, Italy), are less conducive to oak aging and may be better off without its influence.

Oak aging adds extra flavors to the wine and contributes to richer textures. Oak barrels are porous and breathe during direct contact with wine, that helps develop the secondary flavors over a period of aging.

For white wines, the omnipresent Chardonnay benefited the best from oak-aging as evidenced by those beautifully crafted but ultra-expensive Grand Cru and Premier Cru from Chassagne Montrachet and Puligny Montrachet in Cotes du Beane, Burgundy. White varietals like Moscato, Torrontes, Riesling, Gewurztraminer, and, for me, new world Sauvignon Blancs are best made without oak-influence.

• The Type of Oak — Is it French or American oak? This is the most popular debate amongst winemakers when they choose to purchase oak barrels for aging their wine, though we can throw in Hungarian and Slavonian in this discussion too.

Taransaud, Beaune, Allier, Demptos. Sequin Moreau are just some of the more famous French oak brands from renowned cooperages that you hear from wineries and chateau owners. The French oak costs between $800-$1,000/barrel (225-liter size). The American oaks on the other hand can cost just around $400-$600/barrel. So, why opt for more expensive oak barrels then? The flavors imparted by these different oaks differ one from another.

French oak barrels in general, with their tighter grain structure, can soften wine better and manifest flavors of milk cream, spices, cloves, and, when toasted, chocolate and vanilla. American oak barrels, on the other hand, have a looser grain structure and are more robust. This structure enhances stronger influence on the wine, showing flavors of vanilla, coffee, toffee, and nutmeg. It is popular practice to use both American and French oaks in a wine to garner the good qualities of both worlds.

• The Usage of the Oak — Since oak barrels are pretty expensive, not all oak barrels used for aging are new, or virgin. There are those that are second-used and hand-down, up to the third use, depending also on the period of time wine spent in the barrels intended for re-use. There may no longer be flavors left after the third use.

The virgin oaks would impart the most intense flavors, as expected, while only very subtle nuances will be detected from the third use.

An in-house cooperage could, however, re-toast and re-stave the barrel (termed as “hogsheading” in some places), but this will not be as good as the virgin oak, as the barrels will be thinner and devoid of their original flavor intensity.

The most expensive wines in the world —  from classified growths of Bordeaux to new world icons Penfolds Grange, Screaming Eagle and Opus One —  all use virgin oaks exclusively.

• The Toast Level — When oaks are lightly toasted, the wine acquires a subtle creaminess and butter elements, and as the toast gets heavier, the wine will acquire more charcoal-like flavors, developing tobacco, toffee, coffee and dark chocolate type nuances.

The toast level has a lot to do with the style of wine intended. If the winemaker is looking at making bold, full-strength, and masculine wines made from Cabernet Sauvignon or Syrah, the tendency will be to have a heavier toast level. But if the intention is more finesse and an elegant type of wine, the toast level will be light to medium only, like what you will get from the French Meursault (from Burgundy) made of 100% Chardonnay.

• The Aging Period — Only Spain as a country has a law governing the oak aging period in all their wine regions and mandate terms corresponding to the periods of time wine spends in oak. This is an all or nothing rule, meaning the entire wine should be under oak, not a certain percentage of the wine, otherwise this classification cannot be used and manifested in the label. Under the Spanish Denominaćion de Origen (D.O.) laws, below are three general oak aging classifications:

Crianza — defined as wine that had undergone a minimum of six months of oak aging, with another 18 months in bottle aging prior to commercial release; or, another way of putting it is two years minimum cellaring prior to release, of which a minimum of six months should be in oak barrel.

Reserva — defined as wine that had undergone a minimum of 12 months of oak aging, with another 24 months in bottle aging prior to commercial release; or three years minimum cellaring prior to release, of which a minimum of one year should be in oak barrel.

Gran Reserva — defined as wine that had undergone a minimum of 24 months in oak aging, with another 36 months in bottle aging prior to commercial release; or five years minimum cellaring prior to release, of which a minimum of two years should be in oak barrel.

These classifications may vary from region to region, like Spain’s proudest Rioja region, through their Consejo Regulador (regulatory board), bumped up their minimum oak-aging requirement for their Crianza wines to 12 months, six months more than required by this law.

Other than Spain, neighboring Italy and Portugal are doing something similar with their labels. Famous ones include Tuscany’s Chianti Riserva with a minimum of 24 months of oak-aging (and an extra three months bottle aging) and Piedmont’s Barolo with minimum 18 months in barrel (and an extra 20 months bottle aging) before commercial release.

While oak aging cannot cover for a bad harvest, it can still mask some flavors that can improve a wine from bad to tolerable. That is also why only good vintages in Spain normally go through Reserva and Gran Reserva stages, as no bodega (winery) will risk patiently waiting for their inventory to reach higher required cellaring, if their wine will not improve with prolong aging to commercially succeed.

There are many cheaper but nefarious ways of duplicating real oak-aging, including the use of oak chips, oak staves, and even oak essences. Oak chips and oak staves (bigger portions), taken from real oaks are submerged into stainless steel tanks for days and then filtered off upon bottling. Oak essence, on the other hand, is a liquid form of oak flavor concentrate that is added to the wine after fermentation and before bottling.

The New World wine-producing countries, especially Chile and Argentina, are notorious for this. These superficial oak practices in these South American countries are not illegal. These same practices are, however, banned in Europe.

Despite the best “doctored” efforts, all these deceptive means are easily exposed during tastings, especially by discerning wine drinkers. The tendencies of these deceiving oak methods are to overwhelm you on the “nose” side — promising rich flavors, complexity, and texture — but once tasted, the wine will show a light diluted body, a missing mid-palate sensation, and an uneventful aftertaste, totally unlike what real oak aging can truly do.

So next time we drink some premium wines, take note of the flavors imparted by the oak aging, and learn to appreciate the added depth and complexity from the nose or what we call “bouquet,” to the supple texture and lingering finish. The key to an excellent wine is the synergistic integration of wine and oak. Good oak aging, after all, does not lie in the glass and may likewise manifest itself loudly on the price tag.

The author is the only Filipino member of the UK-based Circle of Wine Writers (CWW). For comments, inquiries, wine event coverage, wine consultancy and other wine related concerns, please e-mail the author at wineprotege@gmail.com, or check his wine training website https://thewinetrainingcamp.wordpress.com/services/.