Free and Immobilized Cells of Torulaspora delbrueckii and Lachancea thermotolerans in Sparkling Wine: Innovative Application in Secondary Bottle Fermentation

Sparkling wine production involves secondary alcoholic fermentation, during which carbon dioxide is trapped, creating effervescence and enhancing sensory complexity. This study evaluated the impact of <i>Torulaspora delbrueckii</i> and <i>Lachancea thermotolerans</i> yeast species using free and immobilized cells in secondary fermentation of sparkling wine, in comparison with <i>Saccharomyces cerevisiae</i>. Immobilized <i>S. cerevisiae</i> enabled faster refermentation compared to free cells, while immobilization resulted in a slower process in non-<i>Saccharomyces</i> strains. Biomass monitoring showed stable viable cells for immobilized <i>S. cerevisiae</i> during fermentation, while non-<i>Saccharomyces</i> strains showed a consistent reduction. Volatile profiles were positively influenced by immobilization using <i>S. cerevisiae</i> strains, which produced a constant increase in key aroma compounds, such as geraniol and ethyl acetate, throughout fermentation. Non-<i>Saccharomyces</i> strains contributed to enhanced fruity and floral aromas with variations in volatiles during refermentation. Sparkling wines fermented with immobilized <i>L. thermotolerans</i> were noted for ripe fruit aromas, while <i>T. delbrueckii</i> increased floral notes. <i>S. cerevisiae</i> fermentations showed higher acidity and balanced structure. These findings highlight the influence of yeast species and the yeast immobilization procedures in secondary fermentation, modulating fermentation dynamics and aroma development, and offer a promising strategy to tailor sparkling wine quality and sensory complexity.