Whiskyfässer

Whiskyfässer

What happens in the cask

The reactions that go on in the cask and create whisky are still not fully understood. Ian Wisniewski takes a close look at the most recent research on the subject to see what it can tell us
It’s a ritual for the senses: colour, aroma, texture, flavour and follow-through, making the experience of a dram complete in itself.

But I also relish another form of fulfillment, based on analysis and research: to know how a malt achieves its apotheosis. And that means looking inside a cask, to see what actually happens during maturation.

As a combination of complex reactions that are still not fully understood, the ‘alchemy’ of maturation imbues malt whisky with an irresistible mystique. It’s only since the 1970s-80s that more detailed research into the influence of oak ageing has been undertaken. And as this is something of a work in progress, there’s always a current discovery to discuss.

Maturation can be divided into three elements: subtractive, additive and interactive, which occur simultaneously, albeit at differing rates.

Subtractive maturation deals with the loss of immaturity, while additive maturation sees the oak endowing the spirit with colour and character.

Interactive maturation refers to the complex reactions occuring between the spirit and the oak of the cask, yielding an additional range of characteristics that neither possess individually.

As oak ageing can account for 40-70 per cent of flavour, and the ageing potential of different malts varies, achieving a balance between the distillery character embodied in new make spirit, and the influence of oak ageing, is obviously variable.

How a cask influences maturation depends on various factors. This includes the ‘fill’ (whether filled with spirit for the first, second or third time – the cask’s influence diminishing and changing with each successive fill), the type of oak, American or European, the cask size, ageing environment, and of course the nature of the new make sp....