Before there is bourbon, there is beer. At the Woodford Reserve Distillery in Versailles, Kentucky, this is an impressive sight, and wonderfully aromatic: the unhopped wort from a corn mash fermenting in an open vat constructed of Florida cypress wood. Distillers call this beer a wash.
Corn is deficient in the enzymes necessary to convert its native starches to fermentable sugars during a mash rest. Barley, however, is chock-a-block with the necessary amylases. Thus, there always will be barley malt in an American whiskey grist, although less than 49% and usually much less than that. Scotch whisky (without the 'e'), on the other hand, is distilled from a wash of mostly barley malt.
Bonus pic: a closeup.
Pic(k) of the Week: one in a weekly series of personal photos, usually posted on a Saturday, and often of a good fermentable as subject.