Sparkling Winemaking Using the Achaean Grape Variety Sideritis and the Indigenous Yeast Saccharomyces cerevisiae ABET Isolated from Corinthian Currants: Chemical Composition, Quality Attributes, and Volatilome

The use of indigenous microorganisms in combination with local grape varieties represents a promising strategy for enhancing the local character and authenticity of wines. This study aimed to develop a sparkling wine by combining the Achaian variety Sideritis with an indigenous yeast isolated from local Corinthian currants. The new strain was identified as Saccharomyces cerevisiae ABET, initially evaluated for its fermentation performance in synthetic must, and subsequently used to produce dry and sparkling Sideritis wines in comparison with a commercial yeast (S. cerevisiae cerevisiae 3001 YSEO). ABET successfully completed alcoholic fermentation at 15 and 5 °C, demonstrating its ability to ferment under very-low-temperature conditions. The yeast strain and fermentation temperature affected the physicochemical characteristics and volatilome of the produced wines. ABET produced a distinct, ester-rich volatile profile, particularly at low fermentation temperature, whereas YSEO wines showed a greater relative contribution of higher alcohols. Secondary fermentation further modified the volatilome, and the ABET sparkling wine exhibited higher phenolic content and antioxidant capacity. Methanol was not detected in the must or wines. These findings demonstrate the potential of exploiting indigenous yeast–grape combinations to produce distinctive sparkling wines that reflect regional terroir while contributing to the valorization of the local viticultural biodiversity.