Saturnispora diversa: A New Acid-Reducing Yeast in Co-Fermentation with Saccharomyces cerevisiae to Optimize Flavor Balance in Blueberry Wine

The high acidity of blueberry wine remains a critical factor limiting consumer acceptance. In this study, an acid-reducing yeast strain isolated from naturally fermented blueberry juice was co-fermented with Saccharomyces cerevisiae to evaluate its effects on physicochemical properties and the profile of volatile compounds, characterized using gas chromatography–mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). Results demonstrated that a yeast strain isolated from 484 candidate strains achieved a citric acid reduction rate of 92.04 ± 2.76% and was identified as Saturnispora diversa. This strain has been deposited in the China General Microbiological Culture Collection Center (CGMCC) with the accession number CGMCC No. 28902. Co-fermentation with Saccharomyces cerevisiae significantly reduced the acidity of blueberry wine, while exerting no significant impact on other physicochemical properties. The combined GC-MS and GC-IMS approach provided comprehensive volatile profiling, revealing that Saccharomyces cerevisiae fermentation preferentially enhanced ester biosynthesis, while the acid-reducing co-fermentation system optimized flavor balance. Collectively, the synergistic use of acid-reducing and Saccharomyces cerevisiae offers a promising production strategy for premium blueberry wine, effectively mitigating excessive acidity to improve palatability while preserving aroma integrity.