Chemical and Sensory Characterization of Prunus domestica Wine Aroma Enhanced via Fermentation with Inactivated Rhodotorula mucilaginosa

Rhodotorula mucilaginosa can synthesize carotenoids and various secondary metabolites, promoting the transformation and release of aroma precursors. Co-fermentation with Saccharomyces cerevisiae has been shown to significantly enhance the aroma and improve the color of fruit wines. To address the issue of inhibited growth of R. mucilaginosa during fermentation, the aroma-enhancing effect of inactivated R. mucilaginosa on Prunus domestica wine was investigated, aiming to provide technical support for aroma enhancement in Prunus domestica wine production. Prunus domestica fruit from Yili, Xinjiang, was used as the raw material. After crushing and pulping, S. cerevisiae and inactivated R. mucilaginosa powder were added. Fermentation was carried out at 18-20 ℃ until the residual sugar content in the wine dropped below 2 g/L. After six months of aging, the inactivated R. mucilaginosa-treated Prunus domestica wine (BW) was obtained. Meanwhile, three control wines were prepared for comparison, including conventional Prunus domestica wine (CW, without inactivated R. mucilaginosa), oxidized Prunus domestica wine (OW, without inactivated R. mucilaginosa but with increased oxygen exposure during fermentation), and Prunus domestica-grape blended wine (MW, without inactivated R. mucilaginosa but with mass fraction 50% of the Prunus domestica replaced by "Hutai No. 8" grapes for fermentation). Physicochemical indices, as well as instrumental and sensory analyses of the aroma, were conducted for the four wine samples. Compared with CW, the BW exhibited a significantly lower volatile acid content (P < 0.05) and was the only group in which carotenoids (81.44 μg/L) were detected. The contents of terpenes, C13-norisoprenoids, higher alcohols, and benzene derivatives in BW were significantly higher than those in the other groups, with higher alcohols and benzene derivatives increasing by 32.6% and 14.1% respectively compared with CW. In comparison with CW, the OW showed enhanced levels of volatile phenols and fatty acids, while the MW exhibited increased levels of acetate esters. Quantitative sensory analysis revealed that, compared with CW, OW and MW only showed more prominent sour fruit aromas, whereas the tropical fruit, small berry, and floral notes were significantly enhanced in BW. Partial least squares regression modeling identified terpenes, C13-norisoprenoids, higher alcohols, and benzene derivatives as important contributors to floral, small berry, and tropical fruit aromas, with terpenes and C13-norisoprenoids making the most pronounced contributions. The addition of inactivated R. mucilaginosa powder during fermentation enriched the carotenoid content in the Prunus domestica wine and increased the variety and content of terpenes and C13-norisoprenoids, thereby enhancing the tropical fruit, small berry, and floral characteristics of the wine. It was hoped that this study provided a theoretical basis for the application of inactivated R. mucilaginosa in the aroma enhancement of fruit wine fermentation.