Exploiting Torulaspora delbrueckii to enhance the volatile and sensory profile of Apulian white and rosé wines – impact of co-inoculation vs sequential fermentation strategies

The growing global demand for high-quality wines with distinctive territorial identities has sparked interest in biotechnological innovations, such as the use of non-Saccharomyces yeasts. This study evaluated the impact of a newly isolated strain of Torulaspora delbrueckii (LC 2-1) in combination with a commercial Saccharomyces cerevisiae strain (BW333) on the oenological and sensory profiles of wines from two iconic Apulian cultivars: Verdeca white wines and Nero di Troia rosé wines. Using pilot-scale vinification, three strategies were compared: pure S. cerevisiae fermentation (BW333), co-inoculation (TOR-COI), and sequential inoculation (TOR-SEQ). Fermentation kinetics revealed that TOR-SEQ led to a more gradual sugar consumption, particularly in Verdeca, while maintaining low volatile acidity. Comprehensive GC×GC-MS analysis identified significant shifts in the wine volatilome; the TOR-SEQ strategy nearly doubled total ethyl esters and quadrupled acetate esters in Verdeca wines. In Nero di Troia rosé wines, sequential fermentation triggered a steep increase in grape-derived terpenes and norisoprenoids, such as citronellol and damascenone. Rate-All-That-Apply (RATA) sensory analysis corroborated these chemical findings, with TOR-SEQ wines receiving significantly higher scores for fruity (orange, cherry) descriptors. Hierarchical clustered correlation heatmaps revealed that fermentation-derived esters collectively drove the aromatic profile of Verdeca wines, while a synergistic matrix of aliphatic esters and free monoterpenes dictated the red-berry character of Nero di Troia rosé wines, corroborating the chemical basis of the sensory differences observed. These results suggest that the metabolic impact of T. delbrueckii is highly cultivar-dependent but consistently enhances aromatic complexity. Consequently, the use of T. delbrueckii LC 2-1 via sequential inoculation represents a powerful technological tool to differentiate Apulian wines and meet modern market preferences for sophisticated, fruit-forward profiles.