In 2011 the discovery of a new yeast species Saccharomyces eubayanus was reported. This species was found in the low-temperature forests of Patagonia. Of particular interest was the fact that this species is closely related to the hybrid lager brewing yeast S. pastorianus. Due to its tolerance to cold and its genetic relation to lager yeast, this new species was considered to have potential as an industrial brewing yeast strain, potentially increasing the functional diversity of strains available to the brewing industry, which has traditionally relied on a small number of genetically similar strains.
The industrial potential of this strain was assessed at VTT by measuring a number of characteristics considered important in the brewing industry. These included cold tolerance, fermentation performance and flavour compound production. Several ale and lager yeast strains were included in the study for comparison.
The S. eubayanus yeast was found to be particularly cold-tolerant and was capable of good growth at 10°C. In this respect the new species was similar to a variety of lager yeast referred to as Saaz (after the area in the Czech Republic where they were first used). The superior cold tolerance of S. eubayanus did not however translate to superior fermentation performance and the yeast fermented brewer's wort relatively slowly, though, again, the performance was similar to that of commercial Saaz yeast strains. Interestingly, though fermentation was quite slow, the concentration of higher alcohols and esters (fruit and floral flavours) in the beer was relatively high. This suggests that the yeast could be useful for the generation of low alcohol or non-alcoholic beers, which often suffer from low concentrations of flavour-active compounds.
Natural lager yeast strains are believed to be the result of hybridization between the ale yeast S. cerevisiae and S. eubayanus. The availability of the S. eubayanus parent now offers the opportunity to create new tailor-made lager yeast strains by mating strains of S. cerevisiae and S. eubayanus with specific desirable properties, thereby paving the way for new products and processes in the brewing industry.
Gibson, B. R., Storgårds, E., Krogerus, K. & Vidgren, V. (2013) Comparative physiology and fermentation performance of Saaz and Frohberg lager yeast strains and the parental species Saccharomyces eubayanus. Yeast, 30: 255-266.
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