Fermentation of soybean residue by A. auricula: Mechanisms and uses

The biochemical conversion mechanism of soybean residue by liquid-state fermentation with Auricularia auricula mycelium (AAM) was elucidated through the determination of enzymes and basic nutrients during fermentation as well as the metabolites analysis. The metabolomics analysis was conducted on the differential metabolites of A. auricula using LC-MS/MS and found a total of 351 differential metabolites, including organic acids, sugars, amino acids, phenols etc.; most of which were organic acids, and glycosides. All the differentially expressed compounds were analyzed by KEGG metabolic pathway enrichment. There were 30 metabolic pathways related to the metabolic mechanism of soybean residue conversion; among them, fatty acid synthesis, sugar metabolism, carbon synthesis, and the synthesis of various secondary metabolites were the main metabolic pathways. During the whole fermentation process, the content of flavonoids decreased gradually and its content was 0.001 mg/g after 15 days of fermentation. This indicated that AAM successfully fermented and transformed the soybean dregs into nutritionally rich products. As it was rich in high protein, 3D printing technology was utilized to develop a AAM protein-based cream substitute. The ink exhibited excellent 3D printability owing to its solid viscoelastic behavior. The ink rheology was controlled by XG concentrations, and 3D printed AAM protein emulsion with 2.0% XG showed printing stability. We also produced AAM protein-rich food products using traditional culinary processing techniques. It provided a theoretical basis for realizing the comprehensive utilization of soybean residue and can be used as a new protein source in the food industry with good application prospects. [Display omitted] •Auricularia auricula mycelium fermentation enriches soybean residue nutrition.•Metabolomics reveals 351 metabolites, highlighting fatty and sugar metabolism.•AAM protein emulsion suits 3D food printing with superior rheological properties.•Research turns soybean waste into viable protein sources for food industry.