Identification and Quantification of the Oxidation Products Derived from α-Acids and β-Acids During Storage of Hops (Humulus lupulus L.)

Abstract

α-Acids and β-acids, two main components of hop resin, are known to be susceptible to oxygen and degraded during hop storage, although the oxidation products in stored hops have not been fully identified. In this study, we developed a high-performance liquid chromatography (HPLC) analysis method suitable for separation and quantification of the oxidation products. This HPLC analysis clearly proved, for the first time, that humulinones and hulupones are major products in oxidized hops. We are also the first to identify novel 4'-hydroxy-allohumulinones, suggested to be oxidative products of humulinones, by means of NMR spectroscopy and high-resolution mass spectrometry. Using the developed analytical method, changes in α- and β-acids and their oxidation products during hop storage were clearly revealed for the first time.

Hop beta acids: Properties, significance and utilization.

“…In contrast to other materials, their presence was also confirmed in recent studies (Haseleu, 2009a). Hulupons are formed in hops during long-term storage and together with humulinons they are the main products of natural aging of hops under air conditions (Taniguchi et al, 2013). Data on their content in hops vary.…”

“…Na rozdíl od jiných látek, byla jejich existence potvrzena i v nedávných studiích (Haseleu, 2009a). Hulupony vznikají ve chmelu během dlouhodobé-ho skladování a jsou společně s humulinony hlavními produkty přiro-zeného stárnutí chmele za přístupu vzduchu (Taniguchi et al, 2013). Data o jejich obsahu ve chmelu se rozcházejí.…”

Supercritical carbon dioxide hops extracts with antimicrobial properties

“…trans-Isohumulone, a major bitter flavouring component in beer, when exposed to irradiation might undergo of the transformation in several products containing an enolized cyclic β-triketone moiety: cis-isohumulone, humulone, dehydro-isohumulone, and dehydro-humulinic acid, resulting from the loss of the 4-methyl-3-pentenoyl side chain of trans-isohumulone [21,22]. In the HE and KHE samples, trans-isohumulone and cis-isohumulone were identified.…”

Iso-α-acids, Bitter Components of Beer, Prevent Inflammation and Cognitive Decline Induced in a Mouse Model of Alzheimer's Disease

“…7). A purchased isomerized hop extract (IHE) (Hopsteiner, Mainburg, Germany) with 30.5% (w/v) iso-␣-acids, comprising trans-isocohumulone (1.74% w/v), cis-isocohumulone (7.61% w/v), trans-isohumulone (3.05% w/v), cis-isohumulone (14.0% w/v), transisoadhumulone (0.737% w/v), and cis-isoadhumulone (3.37% w/v), was used to isolate individual iso-␣-acids as previously described (38).…”