Removal of deleterious odor-forming impurities from hop flavors

Abstract

A novel method for the removal of hitherto unrecognized undesirable odor-forming impurities from hop flavors, including unreduced alpha and isoalpha acids and reduced alpha and isoalpha acids, by extracting the impurities from these flavors into water at a pH above 4, preferably above 6 or 7, with or without the presence of salt or solvent, and separating the aqueous phase containing the impurities from the purified hop flavor, as well as the important two-phase and salt-containing intermediate products and the final purified hop flavor which is essentially free of such impurities and which purified isoalpha acid or isohumulone will therefore not produce fruity, estery, sour aromas when used to flavor beverages, e.g., beer or ale, are disclosed. A rapid test for the detection of such aromas, involving dissolution of the hop flavor in ethanol at a concentration of one-half percent w/v and allowing the solution to stand for four days, allows accelerated determination of the presence or absence of such aromas and the odor-forming impurities which cause the undesirable odors.