In order to be called Scotch whisky, it must obviously come from Scotland, but it must also lie in oak barrels for at least 3 years. These barrels can’t be new, they must have some other alcohol in them before. Bourbon, sherry, red or port wine or rum. In addition, there are two other ways to influence the taste of charring. The barrels can be made of American or European oak and can be toasted. By burning, the wood sugars are converted into vanilla or caramel flavors.