BIOTECHNOLOGICAL POTENTIAL AND PROFILE OF VOLATILE COMPOUNDS IN AUTOCHTHONOUS YEASTS FROM STILL-DISTILLED CACHAÇA USED IN BEER PRODUCTION

Stressful fermentation environments, such as cachaça vats in pot stills, harbor indigenous yeasts with untapped biotechnological potential capable of adding regional character and sensory complexity to craft beer production. This study selected and characterized Saccharomyces cerevisiae strains isolated from the bottom of stills in Rio Pardo de Minas, Minas Gerais, and evaluated their fermentative performance and volatile compound profiles for brewing applications on a pilot scale. Yeasts were isolated from three cachaça vats to increase the number and diversity of microorganisms obtained; they were subsequently tested for the absence of H₂S production, carbohydrate assimilation, tolerance to multiple stresses (osmotic, alcoholic, and thermal), fermentative capacity using Durham tubes, and fermentative performance as measured by mass loss. The best-performing strains were used to brew beer using 30 L of water, 8 kg of Pilsen malt, and Cascade hops, with the goal of obtaining a wort with a density of 1.040 g/cm³ and approximately 25 IBU. The wort was divided among four 20-liter fermenters and inoculated with the selected strains and the US-05 reference strain. Fermentation took place at 20°C for 10 days, followed by aging at 6°C for four days and natural secondary fermentation for 14 days after bottling.Of the 338 isolated colonies, 231 were discarded because they grew in the presence of lactose, mannitol, or lysine—undesirable sources of carbon and nitrogen—and 57 because they produced H₂S. Of the 50 preselected isolates, 9 were eliminated in the multiple stress test, and after flocculation, ethanol tolerance, and Durham tube fermentation tests, 14 yeasts advanced to the fermentation evaluation. Of the remaining yeast strains, 3 were selected for pilot-scale production because they exhibited the best fermentative performance in beer wort (45-FB3, 76-FB3, and 161-FB2). The beers produced exhibited physicochemical parameters indicative of rapid initial acidification (pH stabilization at 4.54 to 4.73) and efficient attenuation of soluble solids. The final alcohol content ranged from 4.15% to 5.25% (v/v), with strain 76-FB3 standing out for exceeding the commercial benchmark (4.75% v/v) in sugar conversion efficiency. Gas chromatography analysis (GC-FID/Headspace) confirmed the safety of the beverages, as evidenced by the absence of acetaldehyde and methanol levels below the limit of detection. In terms of its aromatic profile, strain 76-FB3 stood out for its high synthesis of isoamyl alcohol (176.90 mg/L) and 2-phenylethanol (73.37 mg/L), which imparted fruity and floral notes, in addition to the presence of ethyl acetate (43.27 mg/L).  In turn, strain 161-FB2 produced a mild profile, with the exclusive presence of isoamyl acetate (1.75 mg/L). It can be concluded that the native isolates, particularly strain 76-FB3, possess biotechnological potential for the production of craft beers, contributing to the microbiological identity and typical characteristics of the Cerrado.