Phenotypic Diversity and Fermentative Potential of Patagonian Torulaspora delbrueckii Strains for Cider Production

Torulaspora delbrueckii is a promising non-Saccharomyces yeast for beverage diversification, although its diversity and application in cider production remain poorly explored. This study characterized Patagonian T. delbrueckii isolates from wine- and cider-associated environments and evaluated their fermentative potential in apple must. Mitochondrial DNA-RFLP analysis showed that mitochondrial profiles varied according to the isolation source, while physiological characterization revealed differences in temperature, sulfite, and ethanol responses among isolates from different sources. Compared with wine isolates, cider isolates generally exhibited greater tolerance to high temperatures, lower sulfite tolerance, and shorter lag phases under ethanol stress. Eleven representative strains completed apple must microfermentations. Compared with a commercial Saccharomyces cerevisiae strain, T. delbrueckii produced higher glycerol and erythritol concentrations while achieving comparable or higher ethanol levels. Two contrasting strains were further evaluated in sequential mixed fermentations with S. cerevisiae. NPCC1340 enhanced glycerol and erythritol production, whereas NPCC1608 increased malic and succinic acids while maintaining low acetic acid levels. In mixed fermentations, ciders retained the characteristic metabolic profiles of each T. delbrueckii strain, whereas S. cerevisiae improved fermentation performance, producing intermediate fermentation kinetics. These findings reveal phenotypic diversity among Patagonian T. delbrueckii strains and suggest differences associated with their isolation sources, highlighting their potential as starter cultures for producing ciders with distinct chemical characteristics.