The characteristic bitterness imparted by the addition of hops to the brewing process is mainly due to the presence of the bitter acids, which are prenylated acylphloroglucinol derivatives. Bitter acids are divided into the alpha-acids, with humulone the major compound, and the beta-acids, with lupulone the major compound; the alpha-acids isomerize during the brewing process to form iso-alpha acids, which themselves have a bitter taste. These hop acids are vinylogous acids, with acidic ring enols in conjugation with ring and substituent carbonyl groups. Plants in the genus Humulus produce terpenophenolic metabolites. Hops also contain xanthohumol, a prenylated chalcone, and other compounds.
The characteristic bitterness imparted by the addition of hops to the brewing process is mainly due to the presence of the bitter acids, which are prenylated acylphloroglucinol derivatives. Bitter acids are divided into the alpha-acids with humulone the major compound, and the beta-acids, with lupulone the major compound; th,e alpha-acids isomerize during the brewing process to form iso-alpha acids which themselves have a bitter taste. These hop acids are vinylogous acids, with acidic ring enols in conjugation with ring and substituent carbonyl groups. Plants in the genus Humulus produce terpenophenolic metabolites. Hops also contain xanthohumol, a prenylated chalcone, and other compounds.