S. EUBAYANUS AND STRATEGIES FOR ITS APPLICATION IN THE BREWING INDUSTRY

JULIETA BURINI; DIEGO LIBKIND

San Carlos e Bariloche

Workshop; 2nd International Workshop of Brewing Yeasts; 2021

IPATEC - Fundación CRELTEC

Nowadays, non-conventional yeasts are the focus of attention in the brewing industry as tools for innovation. One of special interest is the cryotolerant species Saccharomyces eubayanus, first isolated in 2011 in Patagonia (Argentina). Genetic studies confirmed that hybridization between this species and S. cerevisiae (Ale yeast) gave rise to S. pastorianus (Lager yeast, responsible for 96 % of beer production worldwide). This discovery sparked interest due to the potential application of this wild yeast in brewing. Here, one strain of S. eubayanus (CRUB 1568T) previously selected in our laboratory for its fermentative performance and organoleptic profile, was transferred to three local microbreweries that produced lager beers based on pilsner-style recipes on a scale of 1000-1500 L. When this wild yeast was applied at large scale, it showed poor fermentation performance with similar results among all microbreweries. Fermentations took more than 20 days to complete, almost twice the time compared to lab and semi-pilot scale fermentations. Likewise, an average attenuation of 30 % was observed, half of what was obtained for this strain at laboratory conditions. When brewing fermentations are conducted in large capacity fermenters yeasts are under considerable stress, with great impact on those that are not adapted to that environment. So, it was decided to evaluate whether an increase in oxygen supply throughout fermentation could help to withstand these conditions and improve the fermentation performance on a large scale. Oxygenation regimens were applied within the first 48 hours of fermentation in four microbreweries, finding an improvement in fermentation efficiency, obtaining a complete fermentation in 7 days and reaching attenuation levels of 60 %. It was certainly found that the application of non-conventional yeasts in the industry requires different handling than traditional brewing yeasts, opening a starting point for research and experimentation on the different strategies that can be approached.