Structures of Storage-Induced Transformation Products of the Beerâs Bitter Principles, Revealed by Sophisticated NMR Spectroscopic and LCâMS Techniques
作者:Daniel Intelmann、Grit Kummerlöwe、Gesa Haseleu、Nina Desmer、Kerstin Schulze、Roland Fröhlich、Oliver Frank、Burkhard Luy、Thomas Hofmann
DOI:10.1002/chem.200902058
日期:2009.12.7
exclusively, not the cis‐iso‐α‐acids, were found to be degraded upon storage of beer, the key transformation products formed exclusively from the trans isomers in beer are not known. In the present study, suitable model experiments followed by LC–MS/MS and sophisticated NMR spectroscopic experiments, including the measurement of residual dipolar couplings (RDCs) in gel‐based alignment media as well as a novel
除了令人讨厌的香气发生不良变化外,苦味的强度显着降低以及味道转变为挥之不去的刺鼻苦味,长期以来一直被认为是啤酒的货架期限制因素。多项研究表明,啤酒的老化会导致顺式和反式-异α-酸的总量减少,这是众所周知的啤酒苦味原理。尽管发现在啤酒储存时会专门降解反式-异α-酸,而不是顺式异-α-酸,但关键的转化产物完全是由反式形成的啤酒中的异构体未知。在本研究中,进行合适的模型实验,然后进行LC-MS / MS和复杂的NMR光谱实验,包括在基于凝胶的取向介质以及新型宽带和B 1场补偿后的残留偶极耦合(RDC)的测量令人难以置信的自然丰度双量子转移实验(INADEQUATE)脉冲序列使人们得以鉴定出一系列先前未知的反式异特异异α-酸转化产物,分别是三环香豆酚,三环香豆烯,异三环香豆素,四环香豆酚和表四环香豆酚。这些化合物的HPLC-MS / MS分析显示出上述刺鼻的持久苦味并具有5至70μmolL的阈值浓