Mild heating assisted alkaline pH shifting modify the egg white protein: The mechanism and the enhancement of emulsifying properties

Abstract

Mild heating (20 °C, 40 °C, 60 °C, and 80 °C) for 1 h assisted pH12 shifting on the structural, physicochemical and functional properties of egg white protein (EWP) were investigated. The results of intrinsic fluorescence, surface hydrophobicity, and free sulfhydryl groups indicated that the tertiary structure depolymerized, the hydrophobic groups exposed and the protein subunits dissociated. Fourier transform infrared spectrophotometer and circular dichroism showed that the content of α-helix decreased, and the content of β-turn increased in the secondary structure of EWP. Moreover, the size and zeta potential of EWP12-80 significantly decreased to 119.17 nm (P < 0.05) and −32.53 mV (P < 0.05), and the solution of EWP12-80 was clear and translucent. In terms of emulsification, the emulsion formed from the modified EWP maintained excellent stability in particle size and distribution. Correspondingly, compared with the untreated EWP, the emulsions formed by the modified proteins also had a uniform and stable particle size under the conditions of heating and salt. Therefore, pH12 combined with heating to modify EWP may be an ideal method to improve its functional properties, thereby expanding its use in the food industry.