Yeast Cell Wall polysaccharides in wine aroma stabilisation: Mechanisms, regulation, and applications.

Wine aroma stability is governed not only by the formation and degradation of volatile aroma compounds (VACs) but also by their partitioning and release within the complex wine matrix. Yeast cell-wall polysaccharides (CWPs) and mannoproteins (MPs) have emerged as potential endogenous regulators of these processes; however, the mechanistic links among their structural characteristics, yeast physiology, fermentation conditions, and aroma behaviour remain insufficiently resolved. This review critically examines the roles of yeast CWPs and MPs in wine aroma modulation across molecular, cellular, fermentation, and technological scales. We first summarize the composition and structural features of β-glucans and MPs from Saccharomyces cerevisiae (S. cerevisiae) and non-Saccharomyces yeasts (NSYs), with emphasis on properties that govern molecular accessibility and physicochemical interactions. Current evidence indicates that yeast cell-wall macromolecule-aroma association is a dynamic and reversible process involving matrix-dependent partitioning, hydrogen bonding, van der Waals forces, hydrophobic interactions, and, where applicable, electrostatic effects. Among yeast-derived macromolecules, MP-containing fractions currently provide the most consistent evidence for modulating ester retention and release, whereas the specific contribution of β-glucans remains less established. We further examine how CWP extraction, structural characterization, yeast autolysis, fermentation parameters, including temperature, nitrogen availability, and oxygen exposure, and mixed-culture fermentation influence the abundance and functionality of these yeast-derived macromolecules. Exogenous and endogenous yeast polysaccharides and MPs may influence aroma persistence as well as colloidal stability, mouthfeel, colour, and foam properties, although their effects are highly dependent on macromolecular structure and wine matrix composition. Major knowledge gaps include the lack of quantitative structure-function relationships, insufficient characterization of native cell-wall macromolecular heterogeneity, and the difficulty of distinguishing CWP- and MP-mediated effects from concurrent metabolic and chemical changes during fermentation and ageing. Future research should integrate structural analysis, partitioning and thermodynamic measurements, controlled fermentation experiments, and sensory evaluation to establish mechanistically grounded, application-relevant relationships between yeast cell-wall macromolecular structure and wine aroma behaviour. Overall, yeast cell-wall polysaccharides and mannoproteins are better viewed not as passive binding agents but as dynamic endogenous matrix components that modulate volatile partitioning, retention, and release throughout winemaking and ageing.