Ultrasound-induced changes in structural and physicochemical properties of β-lactoglobulin

Effect of ultrasound treatment on the physicochemical properties and structure of β-lactoglobulin were investigated. β-Lactoglobulin was treated with ultrasound at different amplitudes, temperatures, and durations. The surface hydrophobicity and free sulfhydryl group of β-lactoglobulin were significantly increased after ultrasound treatment ( p < .05). The maximal surface hydrophobicity and free sulfhydryl group were 5,812.08 and 5.97 μmol/g, respectively. Ultrasound treatment changed the physicochemical properties of β-lactoglobulin including particle size (from 1.21 ± 0.05 nm to 1.66 ± 0.03 nm), absolute zeta potential (from 15.47 ± 1.60 mV to 27.63 ± 3.30 mV), and solubility (from 84.66% to 95.17%). Ultrasound treatment increased α-helix and β-sheet structures of β-lactoglobulin. Intrinsic fluorescence intensity of ultrasound-treated β-lactoglobulin was increased with shift of λ max from 334 to 329 nm. UV absorption of β-lactoglobulin was decreased with shift of λ max from 288 to 285 nm after ultrasound treatment. There were no significant changes in high-performance liquid chromatography and protein electrophoretic patterns. These findings indicated that ultrasound treatment had high potential in modifying the physiochemical and structural properties of β-lactoglobulin for industrial applications.