Oak barrels are an essential part of Whisky making. They house the liquid during the maturation process but they also lend some of their woody flavour to the overall taste.
Oak is perfect for Whisky barrels, as it is sturdy yet porous. It will hold the liquid without leaking but is also permeable enough to allow the Whisky to absorb its flavours.
Types of Oak used in Whisky production
There are several different types of Oak and each one imparts a different flavour. The three main ones used in ageing Whisky are:- Quercus Robur (European Oak),
- Quercus Alba (American Oak) and
- Quercus Mongolica (Japanese Oak).
The two most popular types of European Oak are Spanish and French. French Oak creates a fruity flavour that is often very desirable in Whisky.
Sherry Casks
Sherry Casks also give a wonderful spiciness to the Whisky, with cinnamon and cloves really coming through. Think The Macallan, The Glenrothes, Glengoyne or Benromach.
Bourbon Casks
By law, Bourbon barrels cannot be reused to mature Bourbon itself but they are very commonly reused for maturing Whisky.
Charred American Oak gives a great smoky yet sweet flavour. Flavours like vanilla, honey and caramel, along with nuttiness and some spice, are the tell-tale signs of an American Oak cask. Think Irish Whiskey, Kilchoman, Laphroaig, Ardbeg 10 Year Old or Girvan single grain.
Japanese Oak
And that just leaves Japanese Oak or Mizunara, which is of course mostly used for Japanese Whiskies. In the 1930s Japanese Oak became the most popular wood for maturing Japanese Whisky, but unfortunately, it is very soft and porous, making it more likely to leak. As such, like most of the rest of the Whisky world, Japan turned to Sherry and Bourbon casks to mature their liquid. They still use the Japanese Oak casks for finishing their Whisky, giving it honeyed, floral flavours with a slight hint of wooded spice as well. Check out Bowmore's Mizunara Cask Finished Whisky from 2015 to see how it differs from a classic Bowmore Whisky -- delightful!
So yes, the Oak is vital to get right if you want to make a great dram.
