Repurposing brewery contaminant yeast as production strains for low‐alcohol beer fermentation. Issue 1 (2nd November 2021)

• Record Type: Journal Article
• Authors: Krogerus, Kristoffer; Eerikäinen, Ronja; Aisala, Heikki; Gibson, Brian
• Other Names: Boynton Primrose guestEditor.; Cubillos Francisco guestEditor.; Patil Kiran guestEditor.; Stefanini Irene guestEditor.; Stelkens Rike guestEditor.
• Is Part Of: Yeast. Volume 39:Issue 1/2(2022)
• Page Start: 156
• Page End: 169
• Publication Date: 2021-11-02
• Subjects: aldehyde -- brewing -- low‐alcohol -- non‐conventional; Yeast -- Periodicals; Yeasts -- Periodicals; Yeasts -- genetics -- Periodicals; Electronic journals; 547
• DOI: 10.1002/yea.3674
• Languages: English
• ISSNs: 0749-503X

Abstract

Abstract: A number of fungal isolates were recently obtained from a survey of the microbiota of multiple breweries and brewery products. Here, we sought to explore whether any of these brewery contaminants could be repurposed for beneficial use in beer fermentations, with particular focus on low‐alcohol beer. There were 56 yeast strains first screened for the utilization of different carbon sources, ability to ferment brewer's wort, and formation of desirable aroma compounds. A number of strains appeared maltose‐negative and produced desirable aromas without obvious off‐flavours. These were selected for further scaled‐up wort fermentations. The selected strains efficiently reduced wort aldehydes during fermentation, thus eliminating undesirable wort‐like off‐flavours, and produced a diverse volatile aroma profile. Two strains, Trigonopsis cantarellii and Candida sojae, together with a commercial Saccharomycodes ludwigii reference strain, were selected for 30‐L‐scale wort fermentations based on aroma profile and similarity to a commercial reference beer during sensory analysis using projective mapping. Both strains performed comparably to the commercial reference, and the T. cantarellii strain in particular, produced low amounts of off‐flavours and a significantly higher amount of the desirable monoterpene alcohol trans ‐geraniol. The strain was also sensitive to common food preservatives and antifungal compounds and unable to grow at 37°C, suggesting it is relatively easily controllable in the brewery, and appears to have low risk of pathogenicity. This study shows how the natural brewery microbiota can be exploited as a source of non‐conventional yeasts for low‐alcohol beer production. Abstract : A large range of fungal contaminants have been isolated from beer and brewery environments. Here, we screen a library of such contaminants, to explore whether any could be repurposed for beneficial use in beer fermentations. A number of maltose‐negative strains showed promise for low‐alcohol beer fermentation. A strain of Trigonopsis cantarellii, in particular, produced no off‐flavours and higher levels of trans‐geraniol compared to a commercial reference strain.