Selection of indigenous Saccharomyces cerevisiae strains isolated from different spontaneous fermentations for Catharina Sour beer production

Abstract

The expansion of the craft beer market has intensified the search for microbial strains that can enhance sensory complexity and fermentation efficiency. Catharina Sour beer requires yeasts that tolerate low pH, exhibit good attenuation, produce moderate ethanol, and have a balanced aromatic profile. In this study, 11 Saccharomyces cerevisiae strains isolated from different substrates were compared with the commercial strain SafAle™ S-04 to assess their potential to produce Catharina Sour. The strains were evaluated for carbohydrate assimilation and fermentation ability, ethanol tolerance (5.5%), hop resistance, tolerance to acidic pH (3.1), and flocculation. The selected strains were then subjected to sequential microfermentation with Lactiplantibacillus plantarum CCMA 0743. HPLC analyzed physicochemical parameters, organic acids, glycerol, and ethanol, while GC–MS evaluated volatile compounds. The S. cerevisiae strains CCMA 0200 and CCMA 0233 demonstrated superior performance, exhibiting robust carbohydrate fermentation, tolerance to fermentation stress, and flocculation. After lactic acid fermentation, the pH decreased from 5.68 to 3.39, yielding 5.90 g/L of lactic acid. During alcoholic fermentation, the strains produced 3.9–5.0% (v/v) ethanol and approximately 7 g/L of glycerol. Both strains exhibited greater diversity of volatile compounds than the commercial strain, including higher alcohols of sensory relevance. Principal component analysis (PCA) revealed that strains CCMA 0200 and CCMA 0233 formed a distinct cluster from SafAle S-04. These results highlight the biotechnological potential of strains CCMA 0200 and CCMA 0233 to produce Catharina Sour, reinforcing the importance of Brazilian microbial biodiversity as a source of innovation in craft beer development.