Biocontrol Using Torulaspora delbrueckii in Sequential Fermentation: New Insights into Low-Sulfite Verdicchio Wines

Torulaspora delbrueckii has attracted renewed interest in recent years, for its biotechnological potential linked to its ability to enhance the flavor and aroma complexity of wine. Sequential fermentations with a selected native strain of T. delbrueckii (DiSVA 130) and low-sulfite native strain of Saccharomyces cerevisiae (DiSVA 709) were carried out to establish their contribution in biocontrol and the aroma profile. A first set of trials were conducted to evaluate the effect of the sulfur dioxide addition on pure and T. debrueckii/S. cerevisiae sequential fermentations. A second set of sequential fermentations without SO2 addition were conducted to evaluate the biocontrol and aromatic effectiveness of T. delbrueckii. Native T. delbrueckii showed a biocontrol action in the first two days of fermentation (wild yeasts reduced by c.a. 1 log at the second day). Finally, trials with the combination of both native and commercial T. delbrueckii/S. cerevisiae led to distinctive aromatic profiles of wines, with a significant enhancement in isoamyl acetate, phenyl ethyl acetate, supported by positive appreciations from the tasters, for ripe and tropical fruits, citrus, and balance. The whole results indicate that native T. delbrueckii could be a potential biocontrol tool against wild yeasts in the first phase of fermentation, contributing to improving the final wine aroma.