The ideal gift! Buy the best american whiskey online. Price and reviews available for Mellow Corn American Whiskey – 750ml Bottle. Mellow Corn is authentic American Corn Whiskey, a unique kind of straight whiskey that is rarely seen. As corn whiskey, it must be at least 81% corn grain in the mash bill and can be aged in new uncharred or used charred barrels. The forerunner and kissing cousin to Bourbon, American Straight Corn Whiskey has a recipe or mash bill that includes the minimum of 81% corn, the rest being malted barley and rye.