Kentucky Straight Bourbon is a type of whiskey made from a mash of at least 51% corn, with the remainder typically being rye, wheat, and malted barley. It is aged in charred oak barrels for at least two years, and is bottled at a minimum of 80 proof. Kentucky Straight Bourbon is a type of American whiskey that is produced in the state of Kentucky. It is known for its smooth, sweet flavor and is often used in cocktails and mixed drinks.