title: Development of preparative and analytical methods of the hop bitter acid oxide fraction and chemical properties of its components.
abstract: The bitter acids in hops (Humulus lupulus L.) and beer, such as α-, β-, and iso-α-acids, are known to affect beer quality and display various physiological effects. However, these compounds readily oxidize, and the effect of the oxides on the properties of beer or their potential health benefits are not well understood. In this study, we developed a simple preparative method for the bitter acid oxide fraction derived from hops and designated the constituents as matured hop bitter acids (MHBA). HPLC-PDA-ESI/HRMS and MS(2) revealed that MHBA are primarily composed of α-acid-derived oxides, which possess a common β-tricarbonyl moiety in their structures similar to α-, β-, and iso-α-acids. We also developed a quantitative analytical method of whole MHBA by HPLC, which showed high precision and reproducibility. Using our newly developed method, the concentration of whole MHBA in several commercial beers was evaluated. Our results will promote the study of bitter acid oxides.
authors.affiliation: a Central Laboratories for Key Technologies, Research & Development Division , KIRIN Company, Ltd. , Kanagawa , Japan.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Taniguchi
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Matsukura
authors.forename: Harumi
authors.initials: H
authors.lastname: Taniguchi
authors.forename: Hideki
authors.initials: H
authors.lastname: Koizumi
authors.forename: Mikio
authors.initials: M
authors.lastname: Katayama
mesh_terms: D000143:Acids / Q000737:chemistry / Q000302:isolation & purification*; D001515:Beer / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D027582:Humulus / Q000737:chemistry*; D059625:Liquid-Liquid Extraction / Q000295:instrumentation / Q000379:methods; D015588:Observer Variation; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry / Q000302:isolation & purification*; D015203:Reproducibility of Results; D013729:Terpenes / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000143:Acids; D010087:Oxides; D013729:Terpenes
keywords: Humulus lupulus L.; beer; bitter acids; hop; oxidation