Oak & Aging
With wine, beer and most spirits, the special characteristics of the flavour tend to come from the combination of grapes, hops or sugars. Whiskey, however, relies on the quality of the water used during the distillation process and the type and length of cask aging employed.  In many cases, that cask, or barrel, will be made of oak.

The natural question that may follow is, why oak?  What makes this wood the barrel material of choice for most whiskey-makers?

Well, not only does oak have a unique physical and chemical nature, it is a strong wood physically, and its wide radial rays provide strength when it’s shaped for a barrel.  Oak is also considered a "pure wood", particularly when compared against pine or rubber tree wood, which contain resin canals that can pass strong flavors to maturing whiskey.

The natural aspects of oak, once it’s gone through the seasoning and heating treatments required to make it into a barrel, result in the production of pleasant-tasting lactones.  Oak, then, tends to add to the taste and aroma of the whiskey by providing desirable elements from the barrel, such as vanillin, coconut and a bourbon character, as well as toastiness, wood sugars and color. It also has the ability to remove or lessen undesirable elements from newly made spirits, including sulphur compounds and immaturity.

There are thought to be several specific aspects of oak that can influence the maturing spirit.

Hemicellulose, which consists of simple sugars that break down when heated to provide:
• Body, from the addition of wood sugars
• Toasty and caramelized aromas and flavours
• Colour (un-aged whiskey is a clear liquid)

Lignin, the binding agent that holds the cellulose in wood together, when heated yields:
• Vanillin
• Sweet, smoky and spice aromas

Oak Tannins, the naturally occurring preservative compounds that can leave a slightly astringent taste in the mouth (similar to that of strong black tea or fresh walnuts), which play an important role in the maturation process.  Oak Tannins enable oxidation and the creation of delicate fragrances in spirits.

So, it’s easy to see that the barrel, and the type of wood it’s made of, has a significant impact on the taste, aroma, colour and nature of the product that’s aged in it.