Castoreum is a yellowish, strong-smelling secretion that comes from the castor sacs found near the base of a beavers tail. Its an FDA-approved food additive, and hey, you can now get whiskey thats flavored with the stuff. That knowledge comes courtesy of this piece from Food & Wines Mike Pomranz, which spotlights a nice little beaver musk whiskey made by Tamworth Distilling of New Hampshire.