Intelmann Daniel, Haseleu Gesa, Hofmann Thomas
Chair of Food Chemistry and Molecular Sensory Science, Technische Universität Munchen, Lise-Meitner Strasse 34, D-85354 Freising, Germany.
J Agric Food Chem. 2009 Feb 25;57(4):1172-82. doi: 10.1021/jf803040g.
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.
开发了一种用于啤酒中啤酒花衍生苦味化合物的新定量方法。通过在多反应监测模式下运行的液相色谱-串联质谱法，在未经任何净化程序的真实啤酒样品中，首次能够在一次高效液相色谱运行中同时检测到总共26种啤酒花衍生苦味化合物，即异α-酸、α-酸和β-酸的后、共、正、反、前和前反同系物，以及异戊烯基黄酮异黄腐醇和查耳酮黄腐醇。为了补偿液相色谱-串联质谱分析中共萃取基质成分的影响，首次应用所谓的ECHO技术作为定量分析新鲜啤酒和储存啤酒中啤酒花衍生苦味化合物的合适策略。基于定量数据，证实了α-酸和反式异α-酸的显著不稳定性，并且观察到在啤酒储存期间反式异α-酸的降解不取决于同系物链烷酰基侧链的性质。相比之下，在啤酒储存期间观察到β-酸、异戊烯基黄酮异黄腐醇以及查耳酮黄腐醇的浓度增加。
