Effects of mixed microbial fermentation on the quality and metabolite profile of cassava leaf feed based on untargeted metabolomics

Abstract Background Cassava leaves are a major byproduct of cassava processing and have a low utilization rate. In this study, Lactiplantibacillus plantarum , Saccharomyces cerevisiae , and Bacillus subtilis were used for solid‐state fermentation of cassava leaves to improve their feed quality. Results After 48 h of fermentation, the feed pH decreased to 4.3, the crude protein content increased by 3.35%, the lactic acid (LA) concentration increased to 49.44 mg/g, the ammonia nitrogen (AN) and butyric acid (BA) contents decreased, and the sensory quality improved. Scanning electron microscopy (SEM) revealed that the material surface changed from dense to rough and porous after fermentation, Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) indicated that the cellulose I structure was maintained, and thermogravimetric analysis revealed reduced thermal stability of the fermented feed. Untargeted metabolomics analysis identified a total of 1200 metabolites across all samples, with 1008 differentially abundant metabolites screened between the initial and final fermentation stages. The fermentation process significantly enriched pathways such as purine metabolism and nucleotide metabolism and promoted the conversion of flavonoid glycosides into aglycones with higher bioavailability, leading to the accumulation of functional components such as antioxidants. Conclusion This study confirms that mixed solid‐state fermentation can effectively improve cassava leaf feed.