Ethanol Reduction in Montepulciano Wine: Starmerella bombicola Sequential Fermentation at Pilot Scale Under Aeration Conditions

One of the most relevant challenges in winemaking is the increase in the alcohol content of wine, mainly due to climate change. The use of selected non-Saccharomyces yeasts in sequential fermentation with Saccharomyces cerevisiae is one of the effective strategies for dealing with this issue, even if it has been poorly confirmed at the winery level. This work evaluated the use of Starmerella bombicola and commercial S. cerevisiae strains in sequential fermentation at pilot scale in winery conditions to reduce the ethanol content and obtain a wine with enhanced aroma complexity. The results showed that the sequential S. bombicola/S. cerevisiae fermentation in aeration conditions (20 mL/L/min for the first three days) resulted in a reduction in ethanol of 0.80% (v/v) compared to pure S. cerevisiae fermentation. The aeration conditions of sequential fermentation did not affect the fermentation performance of yeasts. The winery conditions determined, in the sequential fermentation modalities, an enhancement of wild yeasts’ presence. At the same time, the inoculation of S. bombicola determined an enhancement of glycerol and lactic acid, which positively influences the structure and body of the wine as well as specific aromatic notes. In winery conditions, better control of fermentation is needed to achieve potential ethanol reduction and favorable by-product formation using S. bombicola.