Several hop derived compounds in wort are known to be converted by yeast during fermentation, influencing the overall perception of the beer. A deeper understanding of such metabolic processes during fermentation is needed to achieve better control of the outcome. Here, the interaction between hop derived compounds and the yeast genera Brettanomyces was studied. Several Brettanomyces strains with different genomic backgrounds were selected, focusing on two traits: beta‐glucosidase activity and nitrate assimilation. The role of three beta‐glucosidases present in Brettanomyces bruxellensis and Brettanomyces anomalus and their impact on the final monoterpene alcohol profile was analysed. The beta‐glucosidase activity was highly strain dependent, with B. anomalus CRL‐49 exhibiting the highest conversion. Such activity could not be related to the release of aglycones from hops during fermentation, as a substantial part of such activity was intracellular. Nevertheless, the reduction of geraniol to β‐citronellol was remarkably efficient for all Brettanomyces strains during fermentation, and it is suggested that two oxidoreductases BbHye2 and BbHye3 may have an influence. Moreover, the transfer of nitrate from hops to wort and its further assimilation by Brettanomyces species was analysed. The amount of nitrate in wort proved to be linearly proportional to the contact time of the hops with the wort. The level of nitrate assimilation by yeast was shown to be dependent on the nitrate assimilation cluster (YNR, YNI, YNT). Hence, the desired yeast strains may be selected according to the genetic make‐up. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling

中文翻译：

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酒杆酵母酵母菌株对啤酒花衍生化合物的生物转化

已知麦芽汁中几种啤酒花衍生的化合物会在发酵过程中被酵母转化，从而影响啤酒的总体感觉。需要对发酵过程中此类代谢过程有更深入的了解，以实现对结果的更好控制。在这里，研究了蛇麻草衍生的化合物与酵母属布雷塔酵母的相互作用。选择了几个具有不同基因组背景的布雷塔酵母菌菌株，重点关注两个特征：β-葡萄糖苷酶活性和硝酸盐同化。目前存在的三种β-葡糖苷酶在Brettanomyces bruxellensis和Brettanomyces anomalus中的作用分析了它们对最终单萜醇谱的影响。β-葡萄糖苷酶活性高度依赖菌株，其中异常芽孢杆菌CRL-49的转化率最高。这种活性可能与发酵过程中啤酒花中糖苷配基的释放无关，因为这种活性的很大一部分是细胞内的。然而，香叶醇还原为β-香茅醇对发酵过程中的所有酒香酵母菌株都非常有效，这表明两种氧化还原酶BbHye2和BbHye3可能有影响。此外，硝酸盐从啤酒花到麦芽汁的转移以及布雷塔菌纲的进一步吸收物种进行了分析。麦芽汁中硝酸盐的含量与啤酒花与麦芽汁的接触时间成线性比例关系。已显示酵母对硝酸盐的同化水平取决于硝酸盐同化簇（YNR，YNI，YNT）。因此，可以根据遗传组成选择所需的酵母菌株。©2020作者。约翰·威利父子有限公司（John Wiley＆Sons Ltd）代表酿酒与蒸馏研究所出版的酿酒研究所期刊