Thermal Modulation of Musalais Wine Characteristics: Volatile Profiles and Chemical Composition at Different Brix Levels

This study investigated the effects of fermentation temperatures (22 °C, 25 °C, 28 °C) and concentrations of grape juice Brix (26 °, 29 °, 32 °) on the physicochemical and aroma profiles of Musalais wine, a traditional fermented alcoholic beverage from Xinjiang, China. The results indicated that higher fermentation temperatures (28 °C) increased total acidity (TA) and residual sugar content (RSC), whereas lower temperatures (22 °C) resulted in higher pH, phenolic content, and anthocyanin content. Ethanol content reached its peak at 25 °C, particularly in Musalais wines produced from 29 Brix of concentrated grape juice. GC-IMS analysis identified 50 volatile organic compounds (VOCs), with esters (30%), alcohols (22%), and ketones (12%) dominating the aroma profile. Wines fermented at 22 °C exhibited the most complex VOC profiles, characterized by fruity esters (ethyl propanoate) and caramel-like ketones (4-methyl-2-pentanone). In contrast, fermentation at 28 °C produced simpler alcohol-dominated aroma profiles. Multivariate analysis (PCA and PLS-DA) confirmed distinct clustering based on temperature, with 19 key markers (ethyl 2-methylpentanoate, 3-octanone) differentiating the Musalais wines. Correlation analysis revealed strong relationships between ethanol, TA, RSC, and specific VOCs. Hierarchical clustering grouped the wines into two categories: those fermented at 22 °C (fruity and rich in complexity) and those fermented at 25–28 °C (alcoholic and simpler profiles). These findings demonstrate that fermentation temperature significantly impacts Musalais wine quality, with 22 °C being optimal for aroma complexity, while 25 °C provided a balance between ethanol production and antioxidant retention. Brix levels of concentrated grape juice modulated acidity and sweetness. This study offers practical insights for optimizing Musalais wine production through controlled fermentation conditions.