Antioxidant activity of yeast peptides released during fermentation and autolysis in model conditions

Abstract

Aging wine on lees benefits different wine sensory and technological properties including an enhanced resistance to oxidation. Several molecules released by yeast, such as membrane sterols and glutathione, have been previously proposed as key factors for this activity [1]. However, recent research testing various yeast extracts from wine lees reported that the improved oxidative stability did not appear to be related to membrane lipids nor directly correlated with glutathione concentration [2,3]. Conversely, chemical and electrochemical tests indicated the extract’s low molecular weight fraction, containing yeast-derived peptides beyond glutathione, as the primary in slowing catechin oxidation in model wine [2]. A subsequent study investigated the peptides’ release under model conditions during synthetic must fermentation and up to six months of lees contact, revealing the release of a significant peptide fraction (~1 g/L) composed of over 2300 sequences identified via LC-MS/MS, whose antioxidant activity was not tested [4].

Building on this approach, the present study examined peptides released after 7 and 240 days from inoculum. After ultrafiltration (MWCO 3 kDa) and purification using C18 cartridges, peptides were quantified with Pierce Quantitative Peptide Assays and their antioxidant activity was assessed with DPPH assay and by measuring their effect in reducing the browning due to the oxidation of catechin in model wine.

Results showed an increase in peptide concentration from 0.19 g/L at 7 days to 0.44 g/L at 240 days. Despite the lower concentration, the 7-day peptide fraction exhibited slightly higher antioxidant activity than the 240-day one (0.32 vs. 0.21 mM Trolox equivalents, respectively). When both peptide fractions were added at the same concentration (0.3 g/L) to a model wine enriched with catechin and exposed to oxygen at 13°C for 50 days, browning development (measured as A450nm) was 10 times lower than that of the untreated control. These results suggest that yeast-derived peptides capable of protecting catechin from oxidation were already present in the system at the end of fermentation.

These findings highlight the role of yeast-derived peptides in protecting wine from oxidation, explaining the reasons behind the application of lees aging and the addition of inactivated yeast extracts for this purpose. Future research will focus on identifying the peptides with antioxidant activities, and also those with antimicrobial properties, providing a wider understanding of the role of yeast peptides in the wine matrix.

References

[1] Salmon, J.M. (2006). LWT – Food Sci. Technol., 39, 959–965

[2] De Iseppi, A.; Curioni, A.; Marangon, M.; Invincibile, D.; Slaghenaufi, D.; Ugliano, M. (2023). J. Agric. Food Chem., 72, 4, 1969–1977.

[3] Bahut, F.; Romanet, R.; Sieczkowski, N.; Schmitt-Kopplin, P.; Nikolantonaki, M.; Gougeon, R.D. (2020) Food Chem., 325, 126941–126941.

[4] De Iseppi, A.; Rocca, G.; Marangon, M.; Corich, V.; Arrigoni, G.; Porcellato, D.; Curioni, A. (2024). J. Agric. Food Chem., 72, 24749–24761.