Relative Bitterness of Reduced and Nonreduced Iso-α-Acids in Lager Beer

The relative bitterness of reduced and nonreduced iso-α-acids in lager beer was measured using a time-intensity protocol in which a trained panel evaluated seven concentrations of each compound in an unhopped lager beer. The peak intensities were measured, and within each panelist, a nonlinear dose-response curve was fit to the data. Equal–bitter relationships over a range of concentrations were created within each panelist for each reduced iso-α-acid/iso-α-acid pair. The parameters of these models were compared statistically using a one-sample, two-sided t-test, and combined groupwise relationships were generated. Accordingly, rho-iso-α-acids were significantly less bitter than iso-α-acids, and tetrahydro- and hexahydro-iso-α-acids were approximately equal in bitterness to iso-α-acids. Results were validated by a consumer panel.