Bioanalytical workflow for exploring the chemical diversity and antioxidant capacity of grape juice peptides

Abstract

The oxidative stability of white wines is related to a flow of chemical reactions involving a number of native wine containing compounds composing their antioxidant metabolome. Our research group could define wine antioxidant metabolome as the sum of molecular antioxidant markers characterized by their radical scavenging and nucleophilic properties ^[1–3]. The significant share of sulfur-containing peptides in wines antioxidant metabolome and their variation according to the vintage, the grape variety and the pre-fermentation oenological practices, shows the need to better explore the grape juice peptidic composition.

In the present work, by the application of biochemical technics, including low pressure purification, protein digestion, gel electrophoresis and size-exclusion chromatography coupled with a light scattering detector, qualitative and quantitative analysis of grape juice derived peptides were performed. Here we describe the optimization of a double digestion protocol used for peptide mapping of grape juice which addresses the challenge of balancing maximum digestion efficiency with minimum artificial modifications. The parameters on which we focused include, digestion time and temperature, as well as the source of acid protease used which are pepsins and Aspergillopepsins I, derived from the controlled fermentation of a selected strain. Using the optimized protocol we generated a pool of peptide compounds, which allowed us to firstly, determine its antioxidant capacity (DPPH essay) and secondly, to explore its chemical diversity by applying LC-MSq-Tof based metabolomics.

The proposed approach allows the validation of a workflow for complete description of peptide composition and antioxidant capacity in grape juices, and opens a new pathway to better manage wines oxidative stability already at the vineyard stage.

References

[1] Romanet, R.; Sarhane, Z.; Bahut, F.; Uhl, J.; Schmitt-Kopplin, P.; Nikolantonaki, M.; Gougeon, R. D. (2021). Food Chem., 355, 129566

[2] Romanet, R.; Bahut, F.; Nikolantonaki, M.; Gougeon, R. D. (2020). Antioxidants, 9 (2), 115

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