Why is Wine Aged in Oak Barrels?
Many of us are aware that most fine wines are aged in barrels made of oak. What is less well known is the reason for this. What are the advantages of oak? What, if any, are the disadvantages? Are there different varieties of oak barrel? Do these affect the wine differently? What are the differences? How does the whole process work?
Aging Wine before Bottling
Once the fermentation process is complete, wine is repeatedly racked to remove the larger solid particles. This young wine is ‘green’. It’s rough and raw and needs time to age in containers that are made of neutral materials. Stainless steel, old casks or cement vats are ideal for this. Alternatively, the wine can initially be aged in small wooded barrels. These are not neutral and will affect the wine as it ages.
Oak Aging Wine
As the wine ages in wooden barrels, subtle flavors from the oak slowly start to affect its development. French or American oak are commonly used. These are sourced from different regions (eg. Nevers, Limousin, Troncais) to impart slightly different flavors (described as ‘vanilla’). Small chemical changes start to work on the wine as it rests in the barrel. The result is a softening of the harsh tannins present during fermentation and a more complex flavor. The different effect of specific woods is a fascinating subject, much discussed by wine makers all over the world. The barrel serves two purposes for the aging wine: it allows oxygen to enter the wine very slowly over time and imparts some of the flavor, or character, of the wood into the wine. A new barrel is best for this and the effect diminishes sharply with repeated use.