Whiskey, cognac, wine, Armagnac, sherry, the list continues. Well known for the maturation of alcohols, Oak wooden casks have become a vital component in the alcohol business. The slightest variation in wood type and finish can have a big difference in the flavour of the finished product.
The Oak is chosen initially depending on its shape and seasoning period. Top-quality straight grained butt oak that has been riven or sawn on the ray is required to ensure the staves bend in the correct way and maintain a watertight cask. The headers and head of the barrels are still made using oak, however, the wooden hoops have since been replaced with iron, as less hoops are then required.
Boards that have been seasoned for longer contain far less tannins. Tannins are responsible for a bitter taste, and so sweeter bourbon liquors are matured in casks using well-seasoned oak. The oak gives a distinct flavour to the liquor through contact, and also partly oak’s more complex ability to allow the cask to breathe slightly. The addition of tyloses in the Oak, adds not only a sugar flavour when the barrels are toasted, but improves on the water tightening of the barrel.
The toasting of the barrel also forces the sugar within the timber to come to the surface and create a caramel. This, when mixed with the raw whiskey dissolves into the fluid, and is the reason for the dark brown colour of matured whiskey.
Charring of the barrels is required for Bourbon and Tennessee Whiskey, which heats up the interior of the barrel to produce charcoal- which subsequently acts as a filter removing bitterness and unwanted flavours from the raw whiskey.
In both events, certain liquors made in oak casks are universally claimed to be superior over those made in other types of container.