Dynamic Changes of Quality Components during Metschnikowia pulcherrima Fermentation of Marselan Wine

To investigate the effect of Metschnikowia pulcherrima (Mp) on key flavor and quality components during Marselan wine fermentation, this study systematically examined the changes in physicochemical parameters, organic acids, and monomeric phenols throughout the fermentation process. In addition, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were applied to elucidate the dynamic evolution of volatile aroma compounds at different fermentation stages. The results showed that total sugar content exhibited a decreasing trend during fermentation, while ethanol concentration and total acid content increased. After fermentation, the contents of organic acids (e.g., tartaric acid, malic acid) and monomeric phenols (e.g., catechin, epicatechin) increased by 13.56% and 25.17%, respectively. A total of 87 volatile aroma compounds were identified throughout the fermentation process, among which 13 compounds had odor activity values (OAVs) greater than 1, mainly comprising alcohols, esters, and terpenes. PCA revealed that the fermentation process could be divided into three stages: the early stage (0~3 d), the mid-stage (5~7 d), and the late stage (9~18 d). Fruity and floral aroma compounds rapidly accumulated in the early stage, peaked in the middle stage, and stabilized in the late stage. PLS-DA further identified eight key aroma compounds (ethyl acetate, linalool, β-damascenone), with ethyl acetate having the highest variable importance in projection (VIP) value. In conclusion, the metabolic characteristics of Mp provide a scientific basis for enhancing the flavor complexity and quality stability of Marselan wine, laying a theoretical foundation for developing innovative oenological microbial resources.