Whisky Scotch whiskies are generally distilled twice, although some are distilled a third time and others even up to twenty times. Scotch Whisky Regulations require anything bearing the label "Scotch" to be distilled in Scotland and matured for a minimum of three years in oak casks, among other, more specific criteria. Any age statement on the bottle, in the form of a number, must reflect the age of the youngest Scotch whisky used to produce that product. A whisky with an age statement is known as guaranteed age whisky. Scotch whisky without an age statement may, by law, be as young
Whisky compound in sherry, and contributes fruitiness to the aroma. The diketone diacetyl (2,3-butanedione) has a buttery aroma and is present in almost all distilled beverages. Whiskies and cognacs typically contain more of this than vodkas, but significantly less than rums or brandies. Polysulfides and thiophenes enter whiskey through the distillation process and contribute to its roasted flavor. Whisky that has been aged in oak barrels absorbs substances from the wood. One of these is cis-3-methyl-4-octanolide, known as the "whisky lactone" or "quercus lactone", a compound with a strong coconut aroma. Commercially charred oaks are rich in phenolic compounds. One study