OXIDATION PRODUCTS OF ISOHUMULONES

Abstract

A complex mixture of oxidation products is formed from iso-α-acids during wort boiling. These substances are already present in hops and persist to beer. Seven major constituents of such a mixture, obtained from pure humulone, were isolated by countercurrent distribution and their structures were elucidated, mainly by mass spectroscopy. The bitterness of the new beer substances was evaluated against trans isohumulone as a reference standard. These oxidation products of iso-α-acids are not extracted with iso-octane and they therefore escape the usual beer bitterness assay.