Whilst the maturation of whisky is often discussed in terms of the pre-seasoning of the casks, the type of oak itself plays a fundamental role in the final character. With the Isle of Raasay Distillery's four-part Oak Species Maturation Series Tasting Pack, the curious will learn first-hand how virgin oak casks create complex and deep flavours in single malt. Matured entirely in Quercus humboldtii, rare Colombian oak, Raasay's whisky develops delicious flavours of crème brûlée and heather smoke. Widely known as European oak, Quercus petraea originates from Hungary. Robust and densely grained, this oak species lends the raw spirit a spicy flavour and wood smoke aromas. The insular single malt owes its warm and lush fruity flavours, caramel and lingering spiciness to the Quercus robur from France, which has a more open and wider grain. With the Quercus muehlenbergii, a Chinkapin oak also takes centre stage. The barrels made from this type of North American white oak are heavily toasted. The effect? A rich colour and a strong aroma of dark fruit and smoky bacon.