What is the primary ingredient that must make up 51% or more of Bourbon whiskey?

The primary ingredient that must make up 51% or more of Bourbon whiskey is corn. Bourbon is a type of American whiskey that is specifically made from a grain mash that contains at least this percentage of corn. This high corn content is what gives Bourbon its distinctive sweet flavor and smooth character, distinguishing it from other types of whiskey such as rye or Scotch, which may have different primary grains and flavor profiles.

The legal definition of Bourbon also stipulates additional requirements, such as being aged in new charred oak barrels and distilled to no more than 160 proof. However, the key characteristic that defines it as Bourbon is the corn content, making it essential for anyone studying this type of whiskey to recognize the importance of corn in its production and identity.