Molecular insights to sorption of aroma compounds by insoluble fractions of specific yeast derivatives

Abstract

Aroma compounds are critical for wine sensory quality, yet their concentration and expression can be altered during winemaking and aging by sorption onto solid surfaces such as oak wood, yeast lees, or yeast derivatives (1-3). While sorption by yeast cell walls is well documented, comparative quantitative studies on different yeast derivative products (SYD) insoluble fractions remain scarce, particularly regarding the influence of surface properties and the sorption reversibility (2; 4-5). This study characterized the sorption of various aroma families by three insoluble fractions of SYDs in a model wine system. Sorption kinetics and isotherms were established and modeled using classical approaches to gain insight into potential interaction mechanisms. The effects of polyphenols and ethanol were also investigated, alongside correlations between aroma physicochemical parameters and surface properties of the SYDs. Finally, desorption experiments evaluated the reversibility of these interactions under varying matrix conditions. For the first time, the sorption capacities of different insoluble fractions of SYDs were quantified and compared, following the order: protein extract (ifPE) > inactivated yeast (ifIY) > cell walls (ifCW). These differences were linked to surface properties, particularly electron donor and acceptor characteristics. Aroma adsorption by insoluble fractions was successfully described using different isotherm models. The Henry model provided the best fit for ifPE indicating linear, non-saturable interactions governed by non-covalent forces while the Freundlich model adequately described adsorption, particularly for ifIY and ifCW, suggesting heterogeneous adsorption sites and potential interactions between aroma molecules. Although hydrophobicity generally correlated with adsorption, we showed that additional physicochemical parameters played significant roles and boiling point emerged as the most influential factor. Polyphenols were also shown to reduce aroma adsorption, either by directly interacting with aroma compounds or by competing for adsorption sites. Overall, modelling proved valuable for understanding adsorption mechanisms and the results highlight the importance of selecting appropriate SYDs according to the wine matrix and the targeted aroma compounds.

References

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