A Novel Approach for Enhancing the Terpenoid Content in Wine Using Starmerella bacillaris

In this study, we investigated the impact of two native strains of Starmerella bacillaris, used both in pure culture and in a co-inoculation with Saccharomyces cerevisiae, on the volatile profile of a chemically defined fermented model must. The focus of this study was the production of monoterpenes and sesquiterpenes and their potential sensory contributions. Geraniol and linalool were detected in all fermentations with Starmerella bacillaris, in ranges of 26.7–43.9 µg/L and 34.3–41.3 µg/L, respectively, independent of the inoculation strategy used. Both strains produced concentrations above their respective odour thresholds of 20 µg/L and 25.5 µg/L. Odour activity value (OAV) analysis confirmed that fermentations with Starmerella bacillaris, particularly under co-inoculation conditions, generated the highest OAVs for these monoterpenes. Citronellol was only detected in mixed fermentations, while nerolidol and farnesol isomers were produced in variable amounts, depending on the strain and inoculation strategy, at concentrations below the odour threshold. These findings demonstrate the ability of Starmerella bacillaris to facilitate de novo biosynthesis of linalool, geraniol, and sesquiterpenes during alcoholic fermentation—in the case of linalool and geraniol, at concentrations exceeding their respective odour thresholds—highlighting the biotechnological potential of these native strains to enhance aroma in wines, particularly those made from neutral grape varieties.