What is spirit maturation?
Cask maturation of a spirit is the effect of innumerable chemical reactions. There are three main influences on the raw spirit –
▪ Wood extraction
▪ Air interaction
▪ Recombination and breakdown within the liquid
Wood extraction is responsible for the colour of the spirit and also donates aromatic components such as vanilla or nutty flavours and aromatic spices. When casks are used that previously held other liquids, as is common for Scotch whisky, their residues in the wood pores will also contribute.
The air in the warehouse can penetrate the casks and interact with the spirit. It is mainly the oxygen that changes the spirit over time by oxidising many different compounds. And finally the various molecules within the liquid are reacting with each other to form new substances.
Speeding up things
There are quite a few distillers who use special methods to speed up maturation. Also there are wooden gadgets sold that are supposed to “enhance” already bottled spirits. But what many do not know is that these methods focus on the wood extraction part of maturation only.
Many distilleries use smaller casks to benefit from the increased surface to volume ratio. If a higher proportion of spirit is in contact with wood, then more wood components can dissolve in the spirit in a given period. A lot of distillers use wood chips to increase wood contact of the spirit.
The speed aged products are often described as having undergone years worth of maturation in only a few months. It is indeed possible to extract a lot of wood flavours in a very short time. But all the other maturation processes are not accelerated at all. Young whisky for example typically has a somewhat rough cereal character that is generally regarded as not very pleasant. This will only mellow out in the cask over the years. Strong wood flavours can mask this youthful character but they can not make it disappear.
All in all, wood extraction does not equal maturation. Due to the laws of chemical kinetics, it is indeed impossible to create the exact same spirit in a shorter time by any method of acceleration.