Anotace:
Beer is an alcoholic beverage consumed worldwide, which is given its typical taste by the presence of hops. Hops contain an array technologically important substances, which are primarily represented by hop resins (humulones, lupulones, humulinones, hulupones, etc.), essential oils (humulene, myrcene, etc.) and tannins (phenolic compounds quercetin, catechin, etc.). In addition to their sensory properties, these molecules contribute to the biological and colloidal stability of beer with their antiseptic and antioxidant properties. Recently, an increased attention has been given to prenylated hop flavonoids, particularly xanthohumol, isoxanthohumol and 8-prenylnaringenin. Xanthohumol is a prenylated chalcone that exhibit antioxidant, anticancer and chemoprotective effects. Its only source in human nutrition is beer, nevertheless a large part of xanthohumol from hops is isomerized by heat to isoxanthohumol and desmethylxanthohumol, from which a racemic mixture of 6- and 8-prenylnaringenins is formed during the beer production. Xanthohumol is also converted to isoxanthohumol by digestion, leading to the formation of 8-prenylnaringenin that is being catalyzed by the enzymes of the intestinal microorganisms as well as liver enzymes. This substance is currently considered to be the most effective natural phytoestrogen.