Non-targeted Metabolomic Analysis of the Effect of g-IDY Addition on Metabolites in Mixed Fermentation Wine

g-IDY was a yeast derivative that replaces SO₂. In order to investigate the effects of g-IDY on metabolites and their metabolic pathways in wine fermented by mixed bacteria (Saccharomyces cerevisiae, Torulaspora delbrueckii CICC 33458, Oenococcus oeni CICC 33458). In this study, UHPLC-MS combined with non-targeted metabolomics technology was used to analyze the metabolites in three groups of wines (single fermentation S group, mixed fermentation TS0 group, mixed fermentation TS60 group with g-IDY) by multivariate statistical method. The study showed that 643 and 293 different metabolites were screened in positive and negative ion modes in TS0 group and S group. Similarly, in TS60 group and TS0 group, 153 and 57 different metabolites were screened in positive and negative ion modes. Subsequently, the differential metabolites with absolute value of log₂(FC)≥1, VIP >1, P<0.05 were further selected and annotated by KEGG database. The study showed that 53 significantly different metabolites were annotated to 16 metabolic pathways in the TS0 and S groups. The mixed-bacteria fermentation was able to up-regulate D-amino acid metabolism, histidine metabolism, amino acid biosynthesis and down-regulate nucleotide metabolism, purine metabolism and other major metabolic pathways by up-regulating the major differential metabolites such as L-glutamine, L-proline, L-histidine, tryptophan, L-lysine and down-regulating cytosolic phosphatidylcholine, and acetylcholine in the wines. Similarly, in the TS60 and TS0 groups, 18 significantly different metabolites were annotated to 8 metabolic pathways. g-IDY was able to upregulate major differential metabolites such as spermidine succinate, 4-aminobutyric acid, D-glucosamine 6-phosphate, and L-glutamine and downregulate guanine, deoxyguanosine, and adenine in mixed-bacteria-fermented wines through upregulation of alanine, aspartate, and glutamate metabolism, histidine metabolism and down-regulate major metabolic pathways such as glycerophospholipid metabolism, and nucleotide metabolism. Through in-depth analysis of the changes and effects of differential metabolites in wines, the results showed that g-IDY was beneficial to the formation of aroma and flavor in mixed-bacteria fermented wine.