The Finnish farmhouse ale sahti is unique in that it is fermented with baking, rather than brewing strains of Saccharomyces cerevisae. The custom of maintaining farmhouse yeast cultures is however no longer practiced in Finland, and much yeast derived diversity in sahti beers has presumably been lost as a consequence. Here, the brewing potential of a number of sourdough derived strains was tested with respect to a number of different fermentation traits. Seven strains originally isolated from Finnish or Italian sourdough cultures were used to ferment high gravity sahti wort (20°P), and fermentation performance together with production of volatile compounds were assessed and compared with a reference baking yeast. Strains differed in terms of fermentation rate, yield, yeast viability and beer flavour profile. All were maltotriose positive, but utilisation varied so that alcohol yield could be greater or lower than that of the reference strain, with values ranging from 6.6 to 7.9% (v/v). Production of aroma compounds was also variable so that it was possible to identify strains producing high levels of esters and those with lower production, which could be used to emphasise flavours originating from raw materials. All strains generated 4‐vinyl guaiacol and so would be suitable for other beers where this is a part of the normal flavour profile. Results suggest that sourdough isolates of S. cerevisiae are suitable for sahti production, but could also be applied to other beer styles as a way to differentiate products. © 2020 The Authors. Journal of the Institute of Brewing published byJohn Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling

中文翻译：

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酵母菌来源的酵母菌株及其在农家酿造啤酒中的潜力

芬兰农舍淡啤酒sahti的独特之处在于，它通过烘烤而不是酿造酿酒酵母来发酵。。然而，在芬兰不再实行维持农家酵母菌培养的习俗，因此，许多酵母菌在萨赫蒂啤酒中产生的多样性可能因此而丧失。在此，针对许多不同的发酵特性，测试了许多源自酵母的菌株的酿造潜力。最初从芬兰或意大利酵母培养物中分离出的7株菌株用于发酵高重力萨氏麦汁（20°P），评估了发酵性能以及挥发性化合物的产生，并与参考发酵酵母进行了比较。菌株在发酵速度，产量，酵母活力和啤酒风味方面有所不同。所有这些都是麦芽三糖阳性的，但是利用率各不相同，因此酒精产量可能高于或低于参考菌株的酒精产量，值范围为6.6至7。9％（v / v）。香气化合物的产生也是可变的，因此可以鉴定出产生高水平酯的菌株和产生较低酯的菌株，这些菌株可以用来强调源自原材料的风味。所有菌株均产生4-乙烯基愈创木酚，因此适用于其他啤酒，因为这是正常风味的一部分。结果表明，分离出的酸面团酿酒酵母适用于萨赫蒂啤酒的生产，但也可以应用于其他啤酒类型以区分产品。©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