Sugar stress attenuates fruity aroma in sweet wine by suppressing ethyl ester biosynthesis: Insights from integrated sensory, metabolome, and transcriptomic analyses

Sugar-induced stress is a key characteristic of sweet wine fermentation, yet its impact on sensory properties remains poorly understood. In particular, the molecular mechanisms behind the reduction of fruity aroma under high-sugar conditions are unclear. In this study, we conducted an integrated analysis combining sensory evaluation, metabolomics, and transcriptomics of wines fermented from grape musts with three initial sugar concentrations (204, 260, and 316 g/L). Sensory and metabolomic profiling revealed that higher initial sugar concentrations resulted in a diminished fruity aroma, which was associated with a reduction in ethyl ester content. Transcriptomic analysis identified differentially expressed genes (DEGs) involved in ethyl ester metabolism, while weighted gene co-expression network analysis (WGCNA) revealed 14 candidate hub genes potentially regulating ethyl ester production in <i>Saccharomyces cerevisiae</i>. These findings provide new insights into the molecular mechanisms underlying the reduction of fruity aroma under sugar stress and offer a theoretical basis for enhancing fruity aroma retention in sweet wine production.