Refinement and aging of wine.

After the fermentation of the grapes and once the various steps of clarification and stabilization have been completed, the wine needs time to mix its components well.  The wine aging process changes, at times drastically, depending on the product in question, the grapes used to produce it, and the intended use of it. 
During the wine aging phase, the wine is kept in containers made with materials that contribute to enriching the aromatic profile of the product.  The wine refinement, be it in steel, wood, or other materials chosen by the producer, allows the chemical reactions in the wine to take place without external elements influencing them.  If this were not the case, uncorking a bottle of wine would be a bit like opening an Easter egg: you never know what you can find there!  The more a bottle of wine is left to age, the more the chemical components it contains will interact with each other, influencing their organoleptic characteristics which, in the meantime, will be enriched with elements given precisely by the contact between the wine and the material in which you keep it.  The duration of wine aging may depend, for example, on the rules dictated by the wine production regulations or on the style desired by the expert winemaker.  A classic example is the various appellations of the Tuscan region, in which they are found from the freshest and most fruity wines such as the Rosso di Montalcino DOC to the austere and structured wines such as the Brunello di Montalcino DOCG. It demonstrates how the different aging can affect the same grape variety, that is Sangiovese.
Let's for example compare wo disciplines: Chianti Classico DOCG and Brunello di Montalcino DOCG. The producer can choose the type of material and shape that best suits the style and result to be obtained.  French and American woods are the most common.  What characterizes the French one is its porosity, which means that it offers greater oxygenation in favor of aromatic complexity.  It is used to produce wines rich in smooth tannins and with sweet spicy notes, such as those of cinnamon and coffee beans.  The American one, on the other hand, is used when you want to give priority to expanding the aromatic range of wines.  Notes of caramel, vanilla, and coconut are common.  In addition to the type, the toasting of the wood plays a fundamental role.  By toasting we mean the exposure of the wooden plates that form the barrel to a flame: depending on the duration of the exposure there is a different influence on the wine.  The final characteristics to be taken into consideration are the size and age of the wooden container: the younger it is, the more the influence of the wood will be predominant and recognizable in the glass.  As for the dimensions, among the most common we find the French barrique of 225 liters, the French foudre, which can reach up to 20,000 liters or the barrels.
Source: European School of Sommeliers, Vini a Tavola