Florian Bahut,* Nathalie Sieczkowski, Régis Gougeon, and Maria Nikolantonaki
*Lallemand, Rue Claude Ladrey, 21000, France (florian.bahut@u-bourgogne.fr)

Inactivated dry yeast (IDY) are gaining interest due to their wide spectra of and enological applications. There is a great diversity of compounds released by specific glutathione-rich inactivated yeast (Bahut et al. 2020): notably, sulfur-containing com­pounds that act as sacrificial nucleophiles in the cascade of phenolic compound oxi­dation reactions. Nucleophiles released from IDY are thus related to their antioxidant activity. To develop a new method to measure this antioxidant activity, and to explore its correlation with the chemical diversity of IDY-released nucleophiles, we propose to measure the characteristic half-life time of a stable isotope-based nucleophile, during controlled oxidation of a standard polyphenol (4-methylcatechol) in model wine, by UHPLC-ESI-Q-ToF MS. We propose that the higher the native nucleophilic environment of IDY-released compounds, the greater the half-life time of the stable isotope nucleophile will be. Competition reactions in the presence of increasing con­centrations of sulfites with the stable isotope-based nucleophile allowed us to build a model to express the characteristic half-life time of the latter in mg/L free sulfites equivalent. This characteristic half-life determined for IDYs is used to classify their nucleophilic composition released into a model solution. This method is a powerful tool to rationalize the antioxidant activity related to the nucleophilic composition of complex matrices and has great potential for development of biological antioxidants for winemaking.

Funding Support: Lallemand