Blog

Why does a wine gain aroma, flavor and structure, when it passes through an oak barrel?

Sep 08, 2020

Aging in wood barrels is an important process to enrich the drink and, in turn, stainless steel tanks are beginning to gain some importance.

For centuries, wines belonged to kings and queens who kept their production in places guarded by guards in wooden barrels. Now and then, when they went to check the drink, they saw that the barrels were no longer as full as they initially were, and often the guards lost their lives for that. One beautiful day, one of them came with a great desire to live, invented a story that wine was so good that the angels came to drink it during the night. Little did they know that this process of – concentrating the wine and decreasing the quantity – was one of the benefits of storing it in oak barrels.

The oak barrel is an essential item in the beverage aging process and has several functions. One of them is the intensification of the color, since the barrels are burned from the inside to seal the wood and decrease the oxygenation and possible oxidation inside the wine and when it is burned, it changes color to the wine, which tends to get darker. It also increases the life span. When a wine begins to oxidize, the color fades.

The other benefit of barrels is the softening of tannins, phenolic compounds that remain in the grape skin. They are sharp, brittle micro-crystals. Therefore, when you try a wine of lesser quality, it “descends” looking like it “scratches” what is unpleasant.

When placed in the barrel, the tannins collide with each other, break into smaller pieces and the drink becomes softer. The wood itself has tannins and the oak is more round, resulting in a more velvety wine.

Another advantage is micro-oxygenation. As much as the barrel is toasted, it remains with micro-pores, generating an exchange of external oxygen with the internal liquid. It is a small amount of oxygen, not to oxidize the wine, but to “tune” it.

The final benefit is the increased structure, which has to do with the chemical part, making the drink richer (the “angels” part, according to the legend). Because of the micro-porosity, the water tends to evaporate, leaving the wine more concentrated, some even becoming almost liqueur.

Oak is ideal
Wine also gains in aromas, but it is not that simple. They are the result of the combination of fruit aromas and the smell of wood. When the two come together, new aromas appear, such as coconut, caramel, …. so it is said that having taste and aroma literally and only from wood is wrong, is considered an error from the oenological point of view. It is from the junction of the two that “aromas” emerge.

Oak is the wood that makes the best interaction. There are even others, such as Portuguese chestnut wood, but this usually ends up with strong aromas and flavor and stands out in front of wine.

And there are two types of oak that stand out: the American and the European. The American is of the Quercus Alba species, which gives a very striking aroma of caramel, even looks like whiskey.

French oak is of the Quercus Robur species and it is more refined, it makes drinks softer. It brings more “elegance”.

The standard wood barrels store 225 liters and this number is not for nothing, as they yield 300 bottles of 750 ml. There are also Spanish wood barrels with 300 liters, which yield 400 bottles.

What about stainless steel tanks?
Stainless steel tanks started to be used in Australia, around the 70s, following the example of milk producers. The big benefit is that they are inert. They don’t taste, taste, it’s just a container. And temperature control is another advantage, allowing the wine to be stored for months without loss of quality. In addition, maintenance is easier and cheaper ”.

However, modern enology technology is changing the importance of stainless steel tanks. Today techniques have already been developed to simulate micro-oxygenation in stainless steel tanks, with oxygen cylinders and everything very balanced.