Effect of magnetic field‐assisted fermentation on the in vitro protein digestibility and molecular structure of rapeseed meal

Abstract BACKGROUND There has been a significant growth in demand for plant‐derived protein, and this has been accompanied by an increasing need for sustainable animal‐feed options. The aim of this study was to investigate the effect of magnetic field‐assisted solid fermentation (MSSF) on the in vitro protein digestibility (IVPD) and functional and structural characteristics of rapeseed meal (RSM) with a mutant strain of Bacillus subtilis . RESULTS Our investigation demonstrated that the MSSF nitrogen release rate reached 86.3% after 96 h of fermentation. The soluble protein and peptide content in magnetic field feremented rapeseed meal reached 29.34 and 34.49 mg mL −1 after simulated gastric digestion, and the content of soluble protein and peptide in MF‐FRSM reached 61.81 and 69.85 mg mL −1 after simulated gastrointestinal digestion, which significantly increased ( p > 0.05) compared with the fermented rapeseed meal (FRSM). Studies of different microstructures – using scanning electron microscopy (SEM) and atomic force microscopy (AFM) – and protein secondary structures have shown that the decline in intermolecular or intramolecular cross‐linking leads to the relative dispersion of proteins and improves the rate of nitrogen release. The smaller number of disulfide bonds and conformational alterations suggests that the IVPD of RSM was improved. CONCLUSIONS Magnetic field‐assisted solid fermentation can be applied to enhance the nutritional and protein digestibility of FRSM. © 2024 Society of Chemical Industry.