Ultrasound-assisted succinylation comprehensively improved functional properties of egg white protein

Abstract

The effects of ultrasound (120 W, 5 min) assisted succinic anhydride (2%, m/v) modification on structure and functional properties of egg white protein (EWP) were studied. Free amino content and ζ-potential of the samples were significantly declined after ultrasound-assisted succinylation modification, indicating that the acylation reaction was successful. The acylation degree was remarkably improved by ultrasound pretreatment. FTIR results illustrated that ultrasound-assisted succinylation conspicuously increased α-helix content of EWP, reduced random coil content, and enhanced structural ordering of protein. From the microstructure, it could be concluded that network structural ordering of protein gel enhanced and the pore size minished. Functional properties results confirmed that modification effect of ultrasound-assisted succinylation was better than that of ultrasound or succinylation alone. Ultrasound-assisted succinylation prominently strengthen the emulsifying activity index (from 10.5 m2/g to 36 m2/g), emulsifying stability index (from 23% to 84%), and foaming ability (from 136% to 202%) of EWP. Likewise, water holding capacity (WHC) of protein gel was strikingly raised. The optical transparency of protein gel was outstandingly reinforced, from micro-transparent to full-transparent state. Research results manifested that ultrasound-assisted succinylation comprehensively improved functional properties of EWP.