Antioxidant inactivated yeast: High potential of non-Saccharomyces specific metabolome

Understanding the contribution of new natural sources of antioxidant compounds to the stability of wines is of great interest in a context of reduction of sulfites. Here, we investigated the antioxidant potential of selected inactivated non-Saccharomyces yeast (INSY) along with related chemical fingerprints, using combined untargeted UHPLC-Q-ToF MS and DPPH analyses. 4 INSY species were compared to a reference inactivated Saccharomyces cerevisiae yeast (ISY) selected for its high antioxidant capacity. Our results show that, all the INSY can accumulate GSH during the specific production process with yields ranging from +170 % to +360 % compared to the corresponding classical production process. The principal component analysis of the 3511 ions detected by UHPLC-Q-ToF-MS clearly grouped INSY by species, independently of the production process. One INSY exhibited equivalent antioxidant capacity to the control ISY, but with a GSH concentration four times lower (4.73 ± 0.09 mg/g against 20.95 ± 0.34 mg/g, respectively). 73 specific ions presenting strong and significant spearman correlation (rho < -0.6, p-value < 0.05) with the DPPH scores, clustered the most antioxidant INSY and the control Saccharomyces in different groups, indicating that the antioxidant capacity of these two products should be driven by different pools of compounds. These results point out that, GSH alone is not relevant to explain the antioxidant capacity of INSY soluble fractions and other more reactive compounds must be considered, which opens an avenue for the selection new species with great enological potential.