Cask ageing is not recommended for all wine-types. White, Rose and young Red wines are meant to be consumed before ageing begins so that we can enjoy the freshness of the primary aromas and flavours. Unlike the above, great White wines and most of the Red ones require ageing in wooden casks or after bottling, so as to improve their character and soften their tannic taste.
During cask ageing, a series of complicated reactions, collectively known as "arranged oxidation", are taking place. The wood, which is porous enough, allows the slow and continues passage of oxygen causing phenolic development, which softens the wine's rough and aggressive character. Moreover, the wood transfers to the wine numerous substances that develop the nose, making it more complex.
Maturation of the wine is further continued in the bottle, known as "reductive ageing" as the cork ensures the absence of oxygen. During this stage, which lasts from a few months to many years, the bouquet of the wine is developed.