What is the primary ingredient in straight bourbon whiskey?

The primary ingredient in straight bourbon whiskey is corn. By law, to be classified as bourbon, the mash bill, which is the mixture of grains used to produce the whiskey, must contain at least 51% corn. This high corn content contributes to the distinct sweetness and rich flavor profile that bourbon is known for. The other grains—such as barley, wheat, and rye—can be included in the mash bill, but they do not represent the primary ingredient. The emphasis on corn is a defining characteristic of bourbon, differentiating it from other types of whiskey.