The great reds of the world, and the majority of notable whites, are aged in oak barrels before bottling. During this process, the wines become “larged”, much more complex, and rich in nuances. The New World countries often use wood chips (from different origins, and toasted) to give more commercial wines aromas of aging. This reduces their costs, labor requirements, and needed facilities… but obviously, the results are not the same as those obtained with true barrel aging.
Good aging consists of two phases: one in the barrel and another in the bottle. In the latter, the wine is polished, rounded and reaches its maximum potential. Therefore, the aging (not preservation) of a wine always involves two phases:
1) The first oxidative phase, which takes place in the barrel.
2) A second reductive phase, which takes place in the bottle.
During the period of maturation or aging, the wine begins to develop its taste qualities, in addition to gaining clarity and stability. Ideal aging takes place in oak barrels (in the past, the use of chestnut and cherry was due more to the availability of this wood than to their capacity to perfect the wine). Wine aged in tanks never reaches the same level of quality. However, before putting a wine in the barrel, we must consider whether the wine is of adequate quality and whether the added value we may get from aging justifies what we pay for the process. The costs of aging are due to:
-The hefty price of the barrel, which varies between €300 and €800 for a volume of 225-300 liters, and a recommended maximum life of 6 years.
– The high cost of labor for filling, cleaning, and racking.
– The wine lost due to its absorption by the wood in a new barrel, which is about 5 liters of wine.
– The investment in equipment.
However, a healthy aging in tanks is preferable to using old barrels of dubious origin and past use (microbial contamination, higher volatile acidity, souring, and the appearance of bad flavors are all potential results).
Among the positive aspects of aging, we must emphasize the critical role played by wood in the evolution of the wines. An oak barrel, made with new, aromatic wood, has a decisive bearing on the aging of wine, especially if it has a promising structure and a healthy tannic richness. The main benefits are:
1º) Transfer of aromas and flavor elements (tannins) in the wood to the wine
2º) Precipitation of unstable substances, increasing clarity
3º) Progressive and permanent micro-oxidation (evolution)
These aspects are in turn conditioned by the origin of oak, the drying process, the technique used to manufacture the barrel, its age, and its use.
The two main groups of oaks, from the enological point of view, are:
1) French oak. This encompasses two major production areas, with different species:
2) American Oak. American oak largely belongs to the species Quercus alba or white oak. It spans the states of Ohio, Missouri, Virginia, Wisconsin, Illinois and Iowa. It is an oak with a strong texture (density) and a fine grain. It is the oak with the lowest tannin content (35 g / kg), but is rich in aldehydes (vanilla scent) and lactones (aroma of coconut). However, it has very little eugenol (clove scent), and therefore gives a more forceful “boisé” (scent of wood) than the French oak, but with fewer tannins. It is certainly not a second quality oak, but its use must be adapted to the grape variety and style of wine you want to develop.
Drying the wood is of great importance. The tree is cut in winter, while it lies dormant, with an internal humidity ranging between 70 and 80%. Staves are prepared (by splitting or sawing) and dried until the internal moisture drops to 15-16%. This process could be achieved through artificial drying with the use of a kiln (which we clearly discourage). Ideally, drying is natural, with the staves stacked outdoors for three years for American oak (very dense), or 1.5-2 years for French oak. Along with a gradual decrease in humidity, the rains wash away the bitter resins and tannins, and UVA rays of the sun change the composition of various substances, rendering them aromatic.
Two factors are decisive for the final outcome: how the staves are created (splitting or sawing), and the toasting of the barrel in the process of constructing it.
1) Obtaining the staves. This process is done prior to drying the wood and depends on the type of oak with which we are working. Following the felling of trees, the trunk is cut into pieces between 0.9 and 1.2 meters in length. These, in turn, are cut into four quarters, and it is here that the differences begin.
2) Toasting the barrel. A Bordeaux barrel is composed of some 33-36 staves, each 27-28 mm. thick. These staves are not attached with nails or rivets, nor do they have joints between them; the only thing that makes a barrel tight and waterproof is the immense pressure between them, created when the staves are curved with the use of heat.
The process is as follows: first the barrel is pre-assembled without the top or bottom, and the staves are held in place with a loop or strap. This is placed over a brazier, whose fire burns the leftover cuttings and chips of oak. This begins to heat the inside of the barrel, which makes the staves more flexible. A rope is placed in both directions around the barrel, forming a crossed shape over the bottom, and is then stretched by a lathe. This begins to gradually bend the staves, which are constantly wetted to prevent cracking. In this way, the barrel eventually acquires the traditional potbelly shape.
The heat, as well as allowing us to shape the wood, also modifies the organoleptic qualities (sight, taste, touch and smell) of the barrel. During aging, the toasted oak transfers aromas to the wine which, in tasting terms, belong to the “empyreumatic” family, and include cloves, vanilla, toasted almond, coconut, smoke, and more. The degree of toast (low, medium or high) obviously determines the content in these compounds.
The ability to age in the bottle is a characteristic of great wines. The changes they experience are many, and very complex. The most obvious are:
-The changes in color. In the case of red wine, for example, we see the evolution of the bright red tone of the young wines to tile and brick hues of wine of greater age.
-The flavor changes. The tannins are softened, leading to a silkier and rounder wine.
-The changes in the aromas, with the development of the bouquet.
In Spain, the global aging (barrel plus bottle) is regulated by the Wine Act of 2003. The use of the terms Crianza (aged), Reserva (aged longer) and Gran Reserva (the longest aged) are protected and can only be applied to wines that belong to a Designation of Origin, and that have spent a certain amount of time in the barrel and the bottle. In the case of D.O. Navarra wines, in terms of aging, we have the following classifications:
Oak: Red wine whose aging period was at least 3 months in oak barrels. This statement was approved by the new regulations of the D.O. Navarra in 2008.
Crianza: Wine which was aged at least 24 months, including:
-For reds, at least 9 months in barrels (previously this was required to be 12 months, but the turnover of barrels and new market demands led to the change).
-For whites, at least 6 months in barrels.
Reserva: For reds, the wine must have been aged in barrel and bottle a minimum of 36 months in total, and at least 12 months of this time must have taken place in barrel.
-For rosés or whites, the wine must have been aged at least 24 months in total, and at least six months of this time must have taken place in barrel.
Gran Reserva: For reds, the minimum aging period must have been 60 months, of which at least 18 months occurred in barrels and the rest in the bottle.
-For rosés or whites, the wine must have been aged at least 48 months, of which at least six months have taken place in the barrel.
This classification of wine as crianza, reserva and gran reserva is given only in Spain and not the rest of the world. Therefore, when you see these terms (such as aged, or reserve wine) on French wines, Italian wines, Californian wines or others, they do not have the same meaning that they have here in Navarra.
Not all wineries have agreed to classify the quality of their wines according to the traditional crianza, reserva and gran reserva, etc. Strictly speaking, these names only indicate the minimum amount of time spent in barrels, and in tanks or bottles. Although a priori, many Spanish consumers think that a reserva is superior to a crianza wine, the new trends run a different gamut, and many winemakers prefer to talk about their high est end brand (their flagship), the second finest brand and so on, without associating the wines with the classifications mentioned above.
Because of this, some of the high quality wines are no longer using these classifications; they prefer to refer to their vineyards, their land, their barrels, etc., when characterizing their wines. This shift is also taking place in other Designations of Origin as well. Today, the two systems coexist in a large number of wineries in Navarra.