Saccharomycodes ludwigii revisited: exploring pilot-scale production and inactivation methods for oenological applications

Saccharomycodes ludwigii is a wine-related non-Saccharomyces yeast known for releasing significant amounts of polysaccharides that contribute to reduced wine haziness and enhanced mouthfeel and colloidal stability. This study focuses on the production and characterization of yeast derivatives from S. ludwigii strain SL#64. Pilot-scale biomass production was optimized in fed-batch mode by maintaining a specific growth rate of 0.073 h-1, near the threshold for respiratory metabolism without ethanol formation, supporting the hypothesis of a Crabtree-positive behaviour in S. ludwigii. Biomass was subjected to six inactivation treatments: thermal inactivation (TI), partial lysis (PL), total lysis (TL), high-pressure processing (HPP), microfluidics (MI), and combined PL+HPP. These produced derivatives with distinct compositional profiles showing nitrogen contents of 0.2–0.6%, total fatty acid of 5.4–6.1%, and polysaccharides ranging from 27.1% to 30.9%. Their technological impact was assessed in laboratory-scale fermentations of Glera grape must with Saccharomyces cerevisiae, using a commercial yeast derivative as reference. The addition of 35 g/hL of each SL#64 derivative enhanced S. cerevisiae growth and fermentation kinetics, with TL showing the strongest effect on fermentation performance (12.74% ethanol and 10.70 g/L of residual sugars). The inactivation technique significantly influenced polysaccharide concentration (174.93 to 255.73 mg/L) and shaped the aromatic profile of the resulting wines. Overall, S. ludwigii may be proposed as a workhorse for the production of customized yeast derivatives with multifunctional applications in winemaking.