Ageing gracefully: the lowdown on maturation
AGEING GRACEFULLY
The Lowdown On Maturation
By Spirits Expert, Andrew Wilson
We want to take you on a whisky journey, sharing our knowledge along the way and some of our favourite tipples too. A question I’m often asked at events is about how the different taste profiles are created and how these can be so diverse, this naturally led me to the subject of this week’s blog and thoughts around the big topic of maturation.
There’s a lot of jargon in the industry, but simply put maturation is all about ageing.
The spirit is left to mature in wooden casks for anywhere between three years through to more than 50. This process allows different flavours to be extracted from the cask depending on the type of wood and sometimes the spirits that have previously been stored in it, together these influence the colour as well as the final taste. Whilst time is important these other factors play a crucial role in turning a relatively young whisky into a fine dram.
Oak wood is the preferred material for whisky casks in Scotland as they make good leakproof containers. American and European oak (Spanish and French) are the most widely used by Scotch whisky producers. European oak is more porous than its American cousin and contains more tannins, imparting woody, spicier notes. American bourbon barrels are likely to have heavily charred interiors whilst European casks are generally lightly toasted.
The image above shows three matching casks and how the different wood can influence and alter the clear liquid, straight (new make spirit) from the still in different ways. These casks are all ex-bourbon American oak hogsheads filled from the same distillation, highlighting the variation that can be achieved from the cask and the way it’s been stored.
Some oaks can be more porous than others, this is due to the growth rates of the trees and means that during the maturation process more of the whisky is absorbed into the wood. The less porous the wood, the less whisky is absorbed. Wood also expands and contracts during maturation due to variations in temperature and humidity.
For example, whisky casks are typically stored on racks in warehouses going up several storeys, the casks on the top storey are the hottest and least humid, while those on the bottom are coolest and most humid. Casks stored at the top are therefore more likely to lose water through evaporation (angels share), making them a higher ABV alcohol, while casks nearer the ground are cooler, but with a high humidity meaning it is less likely to lose water and will remain at a lower ABV.
Spirits tend to evaporate more quickly while they’re young, and slow down as they age. So, at the very beginning, the angels’ share will be right at the top of the spectrum – around 3.5-4% every year. As the years pass, whisky evaporation slows down (it will never stop) and by the end of the maturation period, a 20-year-old spirit for example might have lost 40% of its original volume.
But, with that evaporation, time and the elements of the warehouse the casks will take on distinctive characteristics that create very unique flavours and experiences. Personally, I love a whisky that has matured in a Pedro Ximinez sherry cask, the sweetness from the wood and the colour changes result in a wonderfully caramelly flavoured whisky. Ultimately, it’s all about experimenting to see what you like. Share with us your favourite cask finishes.