These three foundational ingredients are uniformly utilized in all nations that produce whiskey. The world's premium and super-premium whiskeys are matured in oak barrels for a legal minimum of time, depending on the country of origin and its laws. In the U.S., the law demands that Bourbon must spend a minimum of two years in new, charred oak barrels. Alcoholic beverages that have been fermented then distilled using fruit of any type, including grapes, are technically categorized as Brandy. Whiskey is made only from grain , water, and yeast.
Fermentation always occurs prior to distillation in the whiskey-making process.
Intervention by man is not necessary to have fermentation. In the case of Whiskey, the low alcohol, fermented, grain-based liquid is beer . In the case of spirits, fermented grain mash for whiskey or fruit juice for brandy is then distilled to a boil and the vapors are cooled back into liquid form at high alcohol levels. The more distillations, the higher the alcohol percentage. Pot stills are the original variety of still while continuous stills were introduced in the 1820s.