From Vineyard to Side-Stream Utilization: A New Yeast Isolated from Mavrodaphne Grapes for High-Quality Wine Making from Substandard Raisins

The exploitation of agro-industrial side-streams can be a key strategy for sustainable production. The industrial processing of Corinthian currants generates a significant amount of side-stream (substandard raisins, SR) with high nutritional value and potential for biotechnological valorization. Additionally, indigenous microbial resources are increasingly studied for their role in modulating wine profile and secondary metabolites. In this study, a lactic acid-producing yeast isolated from Greek Mavrodaphne wine was evaluated for fermentation performance, oenological characteristics, and volatile profile in both synthetic must and wine from SR extract. The strain, displaying phenotypic traits characteristic of lactic acid-producing non-Saccharomyces yeasts (presumptively Lachancea sp.), exhibited efficient sugar consumption (residual sugars below 0.2 g/L), moderate glycerol production (0.4–0.6% w/v), and significant lactic acid formation (3.2–7.0 g/L). Wines presented acceptable volatile acidity (below 0.91 g/L), total acidity 8.6–10.2 g/L, phenolic content 191–200 mg GAE/L, and antioxidant capacity 39.7–51.1 mg AAE/L. GC-MS analysis identified 51 and 111 compounds in the synthetic and raisin wines, respectively, with esters predominating the aroma profile. SR is a promising fermentation substrate, and the new yeast has potential for biologically acidified wines with modified volatile characteristics, contributing to sustainable side-stream valorization and enhancing terroir expression within the viticultural sector.