Effects of β-Glucan Glycosylation on Functional Properties and Antioxidant Activity of Naked Oat Protein

Naked oat protein and β-glucan were used to conduct glycosylation reaction. The functional indexes of naked oat protein before and after glycosylation were determined. The formation of conjugates in the process of glycosylation was observed, the mechanism of glycosylation modification was analyzed, and in vitro antioxidant experiment was carried out. The results showed that the solubility of glycosylated naked oat protein was improved at pH5, 7, 9 and 11, and increased by 3.06 times at pH5. The foaming property of glycosylated naked oat protein increased significantly in the range of pH3~11, and increased by 5 times at pH5. The emulsifying property and emulsifying stability of glycosylated naked oat protein were increased by 2.48 and 2.59 times at pH5 respectively. SDS-PAGE gel electrophoresis revealed that glycosylation resulted in the formation of macromolecules. Fluorescence spectrum analysis showed that the environment of the system changed to hydrophilicity during the glycosylation reaction. Infrared spectrum analysis reflected the covalent binding between protein and sugar molecules. It was observed by circular dichroism that glycosylation changed the secondary structure of the protein. The DPPH· scavenging rate of glycosylated naked oat protein was 2.13 times higher than that of native protein, when the concentration was 10 mg/mL. The ABTS⁺· scavenging rate of glycosylated naked oat protein was 2.09 times higher than that of native protein, when the concentration was 2.5 mg/mL. The glycosylation of naked oat protein and β-glucan changed the structure of the protein, the conjugates turned to hydrophilicity, the functionality was improved, and the antioxidant activity was stronger than that of the native protein.