Comparative Study on the Mixed Fermentation Process of Germinated Quinoa and Lycium barbarum, and Changes in Metabolites and Microbial Community Before and After Fermentation

Plant-based fermented beverages are increasingly valued for their nutritional and potential health benefits. Co-fermenting nutrient-dense grains with medicinal herbs offers a promising strategy for novel functional drinks. This study investigated the mixed-culture fermentation of germinated quinoa and wolfberry with composite lactic acid bacteria. The synergistic evolution of microbiota and metabolites was elucidated via 16S rRNA sequencing and untargeted metabolomics. Fermentation was carried out at 31°C for 48 h with a wolfberry-to-quinoa ratio of 1:3 (m/m) and 0.05% inoculum. Fermentation drastically restructured the microbial community, where Firmicutes became dominant, and the relative abundance of Lactiplantibacillus reached 82.99%, effectively suppressing potential spoilage organisms. Metabolomic analysis revealed the directional enrichment of functional metabolites, including indole-3-lactic acid, dihydroferulic acid, and acetic acid. Correlation analysis verified that the proliferation of Lactiplantibacillus promoted the accumulation of these beneficial metabolites. Overall, selective proliferation of Lactiplantibacillus concurrently improved microbial safety and functional attributes by orchestrating a synergistic microbiota-metabolism conversion.