Structural and oxidative modifications, and antioxidant activity of β-lactoglobulin treated by ultraviolet light-C and ultrasound

β-Lactoglobulin (β-Lg) was treated with ultraviolet light-C (UV-C) at 11.8 W m–2 or ultrasound at 900 W for 15 or 30 min. All treatments increased the β-structure, free sulfhydryl groups (FSH), dityrosine, and ABTS radical scavenging activity, but decreased the α-helicity, random coils, disulfide bonds (S–S), and intrinsic fluorescence intensity. UV-C treatment produced higher surface hydrophobicity (Ho), carbonyl, dityrosine, and antioxidant activity, and lower fluorescence intensity, total sulfhydryl group (TSH), and S–S compared with ultrasound treatment. UV-C treatment for 30 min gave the maximum Ho, carbonyl, dityrosine, and antioxidant activity, but the minimum TSH and S–S contents from β-Lg. Ultrasound treatment for 15 min produced the maximum β-sheet, TSH, and S–S contents, while treatment for 30 min gave the minimum carbonyl, dityrosine, and antioxidant activity. Data obtained in this study suggest that ultrasound and UV-C treatments demonstrated the potential for improving antioxidant activity in β-Lg, especially UV-C treatment.