Move Over Hops, Yeast Can Give IPAs Their Signature Flavor

The craft brew revolution is fueled by an earnest pursuit of hoppiness.Many craft beer enthusiasts are drawn to the potent, bitter, aromatic flavors of a primo India Pale Ale (IPA), and brewers take pride in delivering a roundhouse kick to mouth in every bottle. Indeed, the names of IPAs often connote a cataclysmic struggle between man and beer: Hoo Lawd, Hopslam Ale, Pound Town, Hoptrocity, Ruination. You get the point.As the names suggest, hops—the flowers of Humulus lupulus—are ke