Abstract
SummaryIncreasing interest in new beer types has stimulated the search for approaches to extend the metabolic variation of brewers’ yeast. Therefore, we tested two approaches using non‐conventional yeast to create a beer with lower ethanol content and a complex aroma bouquet. First, the mono‐culture performance was monitored of 49 wild yeast isolates of Saccharomyces cerevisiae (16 strains), Cyberlindnera fabianii (9 strains) and Pichia kudriavzevii (24 strains). Interestingly, both C. fabianii and P. kudriavzevii isolates produced relatively more esters compared with S. cerevisiae isolates, despite their limited fermentation capacity. Next, one representative strain of each species (Sc131, Cf65 and Pk129) was applied as co‐culture with brewers’ yeast (ratio 1:1). Co‐cultures with Cf65 and Pk129 resulted in a beer with lower alcohol content (3.5, 3.8 compared with 4.2% v/v) and relatively more esters. At higher inoculum ratios of Cf65 over brewers’ yeast, growth inhibition of brewers’ yeast was observed, most likely caused by competition for oxygen between brewers’ yeast and Cf65 resulting in a reduced level of ethanol and altered aroma profiles. With this study, we demonstrate the feasibility of using non‐conventional yeast species in co‐cultivation with traditional brewers’ yeast to tailor aroma profiles as well as the final ethanol content of beer.
Highlights
The brewing industry traditionally uses Saccharomyces species as their workhorse to convert wort into beer
We demonstrate the feasibility of using non-conventional yeast species in co-cultivation with traditional brewers’ yeast to tailor aroma profiles as well as the final ethanol content of beer
A clear clustering is observed per species, indicating that the diversity in volatile organic compounds (VOCs) between the three genera is higher than within one species
Summary
The brewing industry traditionally uses Saccharomyces species as their workhorse to convert wort into beer. Additional research has been done on strain performance, but remarkably this mostly entails single-strain performance (Zhang et al, 2013; Gallone et al, 2016) Often, various approaches such as genome shuffling or adaptive evolution experiments are used to generate new variants of strains with desired traits (Steensels et al, 2014a,b; Snoek et al, 2015). Basso et al (2016), Steensels and Verstrepen (2014) and Steensels et al (2015) reviewed the use of various nonconventional yeasts for wort fermentation using various strategies They all conclude that non-conventional yeast harbours features of interest for industrial fermentation processes, but the use of those species has to be explored further
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