†Chair of Food Chemistry and Molecular and Sensory Science, Technische Universität München, Lise-Meitner-Straße 34, D-84354 Freising, Germany.
‡Bavarian Center for Biomolecular Mass Spectrometry, Gregor-Mendel-Straße 4, 85354 Freising, Germany.
J Agric Food Chem. 2015 Apr 8;63(13):3402-18. doi: 10.1021/acs.jafc.5b00239. Epub 2015 Mar 27.
Recent brewing trials indicated the occurrence of valuable bitter compounds in the hard resin fraction of hop. Aiming at the discovery of these compounds, hop's ε-resin was separated by means of a sensory guided fractionation approach and the key taste molecules were identified by means of UV/vis, LC-TOF-MS, and 1D/2D-NMR studies as well as synthetic experiments. Besides a series of literature known xanthohumol derivatives, multifidol glucosides, flavon-3-on glycosides, and p-coumaric acid esters, a total of 11 bitter tastants are reported for the first time, namely, 1",2"-dihydroxanthohumol F, 4'-hydroxytunicatachalcone, isoxantholupon, 1-methoxy-4-prenylphloroglucinol, dihydrocyclohumulohydrochinone, xanthohumols M, N, and P, and isoxanthohumols M, N, and P, respectively. Human sensory analysis revealed low bitter recognition threshold concentrations ranging from 5 (co-multifidol glucopyranoside) to 198 μmol/L (trans-p-coumaric acid ethyl ester) depending on their chemical structure. For the first time, LC-MS/MS quantitation of these taste compounds in Pilsner-type beer, followed by taste re-engineering experiments, revealed the additive contribution of iso-α-acids and the identified hard resin components to be truly necessary and sufficient for constructing the authentic bitter percept of beer. Finally, brewing trails using the ε-resin as the only hop source impressively demonstrated the possibility to produce beverages strongly enriched with prenylated hop flavonoids.
最近的酿造试验表明，在啤酒花的硬树脂部分中存在有价值的苦味化合物。为了发现这些化合物，采用感官导向的分级分离方法分离啤酒花的 ε-树脂，并通过 UV/vis、LC-TOF-MS 和 1D/2D-NMR 研究以及合成实验确定关键的味觉分子。除了一系列文献中已知的黄腐酚衍生物、合荎草苷、黄酮-3-氧糖苷和对香豆酸酯外，还首次报道了总共 11 种苦味物质，即 1"，2"-二羟基黄腐酚 F、4'-羟基豚草查尔酮、异黄腐醇酮、1-甲氧基-4-烯丙基邻苯二甲酚、二氢环胡卢酮氢醌、黄腐酚 M、N 和 P，以及异黄腐酚 M、N 和 P。人体感官分析表明，根据其化学结构，这些苦味物质的识别阈值浓度范围从 5（合荎草苷）到 198 μmol/L（反式对香豆酸乙酯）不等。首次对皮尔森型啤酒中的这些味觉化合物进行 LC-MS/MS 定量，并进行味觉重构实验，结果表明异-α-酸和鉴定出的硬树脂成分的加和贡献对于构建啤酒的真实苦味感知是真正必要和充分的。最后，使用 ε-树脂作为唯一的啤酒花来源进行酿造试验，令人印象深刻地证明了生产富含prenylated hop flavonoids 的饮料的可能性。
