Preparation of solid-fermented soy sauce in walnut dregs and analysis of antioxidant properties

Abstract

Objective: Walnut soy sauce was prepared with Aspergillus oryzae as a strain, to explore the functional soy sauce. Methods: Based on the preparation of soy sauce. The nutritional components of soy sauce were determined by using high-performance liquid chromatography, automatic amino acid analyzer and gas chromatography. Components less than 10 kDa were separated by using ultrafiltration. Then the peptide content, ABTS, hydroxyl radical scavenging capacity and DPPH radical scavenging capacity in walnut soy sauce fraction were determined. Results: The total content of 16 amino acids in walnut soy sauce was 4.86 g/100 g, and the content of unsaturated fatty acids accounted for 82.84% of the total fatty acids. The peptide content in the walnut soy sauce component was 6.804 g/100 mL. When the concentration of polypeptide was 3.6 mg/mL, the scavenging ability of ABTS of walnut soy sauce component reached 95.13%, the scavenging ability of hydroxyl radical reached 28.20%, and the scavenging ability of DPPH free radical reached 20.08%. Conclusion: The components of walnut soy sauce has high antioxidant properties and its antioxidant capacity is related to peptide content.

Keywords

• walnuts
• soy sauce
• peptides
• solid state fermentation
• abts scavenging ability
• hydroxyl radical scavenging ability
• dpph free radical scavenging ability