White wine lees: unlocking the relationship between chemical composition and antioxidant potential

Abstract

The wine-making process generates numerous by-products at each stage (crushing, fermentation, ageing), including wine lees, which account for almost 25% of the total quantity [1]. Despite their well-recognized oenological properties, such as stabilizing the physico-chemical properties of wine [2], few studies have focused on white wine lees. Our recent work demonstrates their interesting antioxidant potential, as evaluated by the DPPH assay [3], though the compounds responsible remain unclear. While the antioxidant potential of lees during ageing appears linked to GSH and sulfhydryl compounds [4], specific compounds responsible for this potential are still under investigation.

To improve the understanding of the antioxidant properties of white wine lees, a set of 41 white wine lees was collected after alcoholic fermentation (different grape variety, yeast strain, condition of fermentation). A full characterisation of the composition was then carried out for the first time. These included tartaric acid, lipids, proteins, polysaccharides, polyphenols and total sulfhydryl compounds. Then, a targeted quantification of polyphenols (phenolic acids, flavanols, flavonols, stilbenoids) and glutathione (reduced and oxidised form) was performed by UHPLC-HRMS. In parallel, the free radical scavenging capacity of white wine lees was evaluated using the DPPH method.

The results revealed significant variability in composition and antioxidant capacity, highlighting the diversity of our collection of white wine lees obtained under different conditions. Subsequently, a Spearman correlation analysis was conducted to study the impact of composition on the radical-scavenging potential of white wine lees. Concerning the global compositional parameters, correlation analysis showed a significant positive impact of total polyphenols (ρ = 0.66) and total sulfhydryl compounds (ρ = 0.53) on the antioxidant potential. Targeted analysis of polyphenols and glutathione by UHPLC-HRMS confirmed the importance of polyphenols in the antiradical capacity of white wine lees, with a strong correlation observed for phenolic acids and in particular hydroxycinnamic acids (ρ = 0.80). However, the absence of a significant correlation with glutathione (ρ = 0.23) suggests that other sulfhydryl compounds contribute to the antioxidant potential.

These findings provide valuable insights into the bioactivity of white wine lees. From a valorization perspective, this by-product could be a new source of high added-value antioxidant compounds with promising applications across various industries.

References

[1] Melo, F., Ferreira, V., Barbero, G., Ferreira, E., Umsza-Guez, M. (2024). Foods, 13(13), 2060

[2] Fornairon-Bonnefond, C., Camarasa, C., Moutounet, M., Salmon, J.-M.. (2001). OENO One., 35(2), 57–78

[3] Poulain, B., Hsein, H., Tchoreloff, P., Nioi, C. (2024). Journal of Bioprocessing & Biotechniques, 14(01), 1–14

[4] Romanet, R., Gougeon, R., Nikolantonaki, M (2023). Antioxidants., 12(2), 395