Effect of Dielectric Barrier Discharge Plasma-assisted Glycation on the Antioxidant Activity of β-Lactoglobulin and Its Structure-Activity Relationship

This study examined the antioxidant activity of β-lactoglobulin (β-LG) and its hydrolysate after the treatment of dielectric barrier discharge (DBD) plasma-assisted glycation. The relationship between the structure and antioxidant activity of β-LG was analyzed by measuring the internal fluorescence, ultraviolet absorption spectrum, sulfhydryl content, surface hydrophobicity, average particle size, and secondary structure of treated β-LG. The results showed that after DBD plasma-assisted glycation for 5 min, the DPPH radical scavenging capacity of β-LG reached 129.8 μmol trolox equivalent (TE)/g, and the iron reduction capacity was increased to 75.1 μmol Fe2+/g. The hydrolysate exhibited further enhancement in both DPPH radical scavenging capacity and iron reduction capacity, reaching 193.5 μmol TE/g and 95.5 μmol Fe2+/g, respectively. After DBD plasma-assisted glycation for 5 min, the endogenous fluorescence, ultraviolet absorption intensity, the relative content of α-helix, sulfhydryl group content and surface hydrophobicity (P<0.05) of β-LG significantly decreased, whereas the average particle size and the relative content of β-fold increased. In conclusion, DBD plasma-assisted glycation can effectively improve the antioxidant activity of β-LG by changing its structure.