Abstract 2-Mercapto-3-methyl-1-butanol (2M3MB) imparts an onion-like off-flavor to beer and is believed to result from the hot aeration of brewer's wort. However, little has been reported regarding the mechanism of formation of 2M3MB. In this study, the origin of a 2M3MB precursor (2,3-epoxy-3-methylbutanal, EMB) and the mechanism of formation of 2M3MB from EMB were investigated. EMB was generated by oxidation of the side chain of iso-alpha acids from the hops. It was revealed that EMB reacts with hydrogen sulfide to give 2-mercapto-3-hydroxy-3-methylbutanal, which is then converted into 2M3MB by yeast. When the concentrations of these compounds were measured during beer fermentation using gas chromatography/mass spectrometry, it became clear that only a portion of EMB was converted into 2M3MB, since the majority of EMB was reduced to 2,3-epoxy-3-methylbutanol without conversion to 2M3MB.

中文翻译：

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阐明啤酒中 2-Mercapto-3-Methyl-1-Butanol 的形成机制。第一部分：确定发酵过程中的关键因素

摘要 2-Mercapto-3-methyl-1-butanol (2M3MB) 会给啤酒带来类似洋葱的异味，据信是啤酒麦芽汁热曝气的结果。然而，关于 2M3MB 的形成机制鲜有报道。在这项研究中，研究了 2M3MB 前体（2,3-epoxy-3-methylbutanal，EMB）的起源和从 EMB 形成 2M3MB 的机制。EMB 是通过氧化啤酒花中异α 酸的侧链产生的。结果表明，EMB 与硫化氢反应生成 2-mercapto-3-hydroxy-3-methylbutanal，然后被酵母转化为 2M3MB。当使用气相色谱/质谱法在啤酒发酵过程中测量这些化合物的浓度时，很明显只有一部分 EMB 转化为 2M3MB，因为大部分 EMB 减少到 2，