Irish whiskey & the licence to experiment with non-oak maturation

The maturation requirements for Irish whiskey echo many of the Scottish requirements outlined in The Scotch Whisky Regulations 2009.

Both the Scotch Whisky Regulations and the Irish Whiskey Technical File 2014 strictly outline that their whisky/whiskey cannot be matured in barrels that have a volume in excess of 700 litres. Both require maturation to take place for a minimum of three years and neither allow any additives except for caramel E150A.

There is one significant aspect pertaining to Irish whiskey, however, that you will not find permitted in Scotland. That is the allowance of wood species other than oak for maturation, i.e. non-oak maturation.

The Scotch Whisky Regulations require “the mandatory use of oak casks” for maturation. Whereas the Irish Whiskey Technical File simply requires the use of “wooden casks”.

This gives Irish distilleries and brand owners an incredibly liberal licence for experimentation with their spirit that cannot, realistically, be rivalled by most other whiskey producing regions. Irish whiskey producers arguably have an incredible advantage in terms of flavour, innovation and competition globally.

Non-oak species of wood are becoming increasingly popular for both full maturations as well as cask finishes. As more and more Irish distilleries experiment with these rare, non-oak barrels the understanding and confidence of how each type of wood interacts with the whiskey grows. It is therefore becoming a strong category differentiator.

Showcasing the industry’s zeal for experimentation and innovation, honing the unique flavours produced by non-oak species of wood will hopefully allow these unusual barrel types and flavours to become one of the key successful hallmarks of the Irish whiskey market in years to come.

One limiting factor of these non-oak species, however, is their availability. As there are very few industries that are legally allowed to utilise non-oak species of wood, there are very few cooperages in the world that are actively crafting the casks. Thankfully, some industries – such as wine and white spirits such as craft gin – have begun utilising these unique casks in recent years which is improving the supply and accessibility.

Currently, in Ireland, there are numerous distilleries experimenting with a myriad of non-oak species of wood for both maturating and finishing spirit. Here's a selection of the hard and soft wood trees that are being coopered into casks and used for maturing Irish whiskey:

Most of these non-oak species of wood are currently being sourced from continental European managed forests. Some species are sourced further afield, however, such as Amburana (a hardwood sourced directly from Brazil). 

At this exploratory stage into non-oak species of wood, casks are usually delivered freshly coopered, with the level of char or toasting specifically chosen by the distillery. As such, these casks are usually not seasoned before use which delivers a great wood influence from the cask, unmasked by the presence of a previous spirit or wine.

This material is taken from the Maturation module of the Certificate in Irish Whiskey. Exploring the world of Irish whiskey across eight modules, this fun and accessible online course - written by Irish whiskey experts Fionnán O’Connor and Matt Healy - will boost your appreciation of all things uisce beatha. Buy the course or try a Free Preview here.