title: Qualitative determination of β-acids and their transformation products in beer and hop using HR/AM-LC-MS/MS.
abstract: Hops represent an important source of β-acids with antimicrobial and sensory properties. Transformation products of β-acids formed during their oxidation, mainly hulupones, have been shown to have an interesting kind of bitterness. Their structures were recently elucidated using LC-TOFMS and 1D/2D NMR in solution after thermal treatment of the hop β-acids. This study demonstrates the advantages of MS detection with high resolution and accurate mass measurements. The structure of transformation products in an experimental solution of oxidized β-acids was elucidated using a newly developed method by hybrid quadrupole-Orbitrap MS. In addition to already known structures, two new ones were identified and named epoxycohulupone and epoxyhulupone. The method was verified on real samples; the profiles of these products in Sládek hops harvested in 2008 and 2012 and in corresponding beers were compared. For this purpose, a new QuEChERS assay was used for the preparation of beer samples.
authors.affiliation: Research Institute for Brewing and Malting, Prague PLC, Lı́pová 15, CZ-120 44 Prague 2, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Dušek
authors.forename: Jana
authors.initials: J
authors.lastname: Olšovská
authors.forename: Karel
authors.initials: K
authors.lastname: Krofta
authors.forename: Marie
authors.initials: M
authors.lastname: Jurková
authors.forename: Alexandr
authors.initials: A
authors.lastname: Mikyška
mesh_terms: D001515:Beer / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D027582:Humulus / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure; D010084:Oxidation-Reduction; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013649:Taste; D013729:Terpenes / Q000032:analysis* / Q000737:chemistry
chemical_list: D013729:Terpenes; C008299:lupulon