Optimization of Fermentation Process of Wheat Germ Protein by Aspergillus niger and Analysis of Antioxidant Activity of Peptide

Utilizing wheat embryos as the raw material and employing Aspergillus niger as the fermentation strain, wheat embryo polypeptides were produced through microbial liquid fermentation. The protein concentration post-fermentation served as the response variable, and the preparation process underwent optimization through single-factor testing and a response surface methodology, followed by the assessment of antioxidant activity. The findings revealed that the optimal conditions for wheat embryo peptide preparation via Aspergillus niger fermentation included a fermentation duration of 24 h, an inoculum volume of 4%, an initial pH of 7, and a protein concentration of 21.47 mg/mL. Peptides with different molecular weights were then prepared by dead-end filtration. The results showed that F6 (<3 kDa) had strong scavenging ability against DPPH, ABTS, and ·OH radicals, which provided a basis for the preparation of antioxidant peptides in wheat germ and related research.