title: LC-MS/MS quantitation of hop-derived bitter compounds in beer using the ECHO technique.
abstract: A new quantification method for hop-derived bitter compounds in beer was developed. By means of LC-MS/MS operating in the multiple reaction monitoring mode, a total of 26 hop-derived bitter compounds, namely, the post-, co-, n-, ad-, pre-, and adpre-congeners of iso-alpha-acids, alpha-acids, and beta-acids, as well as the prenylflavonoid isoxanthohumol and the chalcone xanthohumol, could be simultaneously detected for the first time in a single HPLC run in authentic beer samples without any cleanup procedures. To compensate for the effect of coextracted matrix components in LC-MS/MS analysis, the so-called ECHO technique was applied for the first time as a suitable strategy for the quantitative analysis of the hop-derived bitter compounds in fresh and stored beer. On the basis of quantitative data, the remarkable instability of alpha-acids and trans-iso-alpha-acids was confirmed, and it was observed that the degradation of trans-iso-alpha-acids during the storage of beer is not dependent from the nature of the alkanoyl side chain of the congeners. In contrast, an increase of the concentrations of beta-acids and of the prenylflavonoid isoxanthohumol as well as of the chalcone xanthohumol during the storage of beer was observed.
authors.affiliation: Chair of Food Chemistry and Molecular Sensory Science, Technische Universität Munchen, Lise-Meitner Strasse 34, D-85354 Freising, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Intelmann
authors.forename: Gesa
authors.initials: G
authors.lastname: Haseleu
authors.forename: Thomas
authors.initials: T
authors.lastname: Hofmann
mesh_terms: D001515:Beer / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D053138:Cyclohexenes / Q000032:analysis / Q000737:chemistry; D005419:Flavonoids; D005519:Food Preservation; D027582:Humulus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009812:Odorants / Q000032:analysis; D011427:Propiophenones / Q000737:chemistry / Q000302:isolation & purification; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013649:Taste; D013729:Terpenes / Q000032:analysis / Q000737:chemistry
chemical_list: D053138:Cyclohexenes; D005419:Flavonoids; D011427:Propiophenones; D013729:Terpenes; C007966:humulon; C104536:xanthohumol