BREWING PROPERTIES OF SACCHAROMYCES EUBAYANUS SUB-POPULATIONS

JUAN IGNACIO EIZAGUIRRE; JULIETA BURINI; DIEGO LIBKIND

Bariloche

Simposio; 34TH INTERNATIONAL SPECIALIZED SYMPOSIUM ON YEASTS; 2018

International Commission for Yeasts (ICY)

The discovery in Patagonia of the missing close relative of Lager-brewing yeasts,Saccharomyces eubayanus, solved a mystery that had puzzled scientists and brewersfor decades. In recent years additional strains were found in North America, Asia andNew Zealand, as well as in Patagonia and genomic analyses showed the existence oftwo main populations of this yeast. In this work we focused in S. eubayanus subpopulations,which are geographically structured. From previous work where 60 strainswere tested we selected at least two strains for each sub-population and tried them inmicro-fermentations (150 ml). Strain selection criteria were attenuation andfermentation rate, and 10 selected strains were tested for sugar consumption, production of glycerol and ethanol, production of phenols and sensory analysis. S.eubayanus strains, showed an average attenuation of 65% due to an efficientconsumption of maltose, with the exception of a geographically distant strain (Tierradel Fuego). None of the strains were able to consume maltoriose. All the strainsproduced phenolic off flavors (+pof) above the sensory threshold, a clear trait for nondomesticatedstrains. Genomic analysis confirmed the presence of active PAD1 andFDC1 genes. Although these compounds are undesirable in typical Lager beers, thedifferent concentrations produce a variety of flavors that could be used for productdifferentiation. To date attempts to generate novel Lager hybrids mostly used S.eubayanus CRUB1568T as parental. This work represents the first screening of brewingperformance of a large set of isolates of S. eubayanus yielding new interestingcandidates for future hybridization programs aiming at creating new lager yeast for industrial innovation.