Maillard reaction enhances prebiotic potential of silver carp hydrolysates: Insights from SCFA production, microbiome, and metabolomics

Silver carp ( Hypophthalmichthys molitrix ) is a low-cost, protein-rich freshwater fish with high nutritional value but remains underutilized in functional food applications. Our previous studies have demonstrated that silver carp hydrolysates (SCH) possess potential in the management of chronic diseases and that their sensory properties and antioxidant activities can be further enhanced through Maillard reaction. However, the prebiotic potential of Maillard reaction-modified SCH has been rarely explored. This study investigates the prebiotic potential of SCH-based Maillard reaction products (SCH-MRPs) using in vitro fermentation model combined with 16S rRNA sequencing and metabolomics. During the fermentation process, moderate Maillard reaction significantly promoted SCFA production (approximately 16.29 %) ( p  < 0.05), particularly acetic, propionic, and butyric acids, which are known to play key roles in maintaining intestinal health and immune function. These changes were associated with increased microbial diversity, as indicated by higher Shannon (41.44 %) and Simpson (18.30 %) indices, along with a 264.24 % increase in the relative abundance of Bacteroides . Metabolomics analysis revealed differential metabolites in the SCH-MRPs group suggested potential involvement in regulating tryptophan metabolism and bile secretion pathways, including indole-3-carboxaldehyde, indolepropionate, and glycochenodeoxycholic acid 3-glucuronide. Correlation analysis showed significant positive correlation between Fusobacterium , Bacteroides , and unidentified_Clostridiales abundances with indoles and derivatives, suggesting a regulatory role in tryptophan metabolism. This study systematically explores the prebiotic potential of Maillard reaction-modified SCH conjugated with oligosaccharides. By integrating microbial community analysis and metabolomics, it reveals a dual effect of SCH-MRPs in enhancing gut microbiota composition and metabolic activity, offering a promising strategy for microbiome-targeted functional food development.