<P> Other than an age statement, which is a direct reference to the age of the youngest spirit in a bottle, the only other special labeling dealing with the age of a straight whiskey in the U.S. is bottled in bond . All bonded whiskeys are required to be straight whiskeys, and are additionally required to be aged for at least four years . Bonded whiskeys must also fulfill several other requirements.: </P> <P> When at least 51% of the content of the mash used in the distillation of a straight whiskey consisted of corn, rye, barley, or wheat, the designation can be coupled with a special name associated with the type of grain and whether the grain was malted . For example, a straight whiskey may be a bourbon whiskey (using a mash of corn), malt whiskey (using a mash of malted barley), rye whiskey, rye malt whiskey, or wheat whiskey . An especially prominent variation is the labeling "Kentucky Straight Bourbon Whiskey", used to indicate a straight whiskey made in Kentucky from a mash of at least 51% corn grain . </P> <P> For a straight whiskey to be called corn whiskey, it must use a mash with at least 80% corn and be aged in used or uncharred barrels . </P> <P> Extra ingredients, such as caramel coloring, are forbidden in straight whiskey . To contrast, even the regulations governing single malt whiskey production in some countries allow the addition of caramel coloring to enhance appearance . </P>

What is the difference between burbin and whiskey