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

Mild heating (20 degrees C, 40 degrees C, 60 degrees C, and 80 degrees 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 alpha-helix decreased, and the content of beta-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.

Automated summary

Mild heating combined with pH12 shifting was found to modify egg white protein in terms of its structural, physicochemical, and functional properties, leading to changes such as depolymerization of tertiary structure and decreased size and zeta potential. The emulsions formed from the modified proteins also showed improved stability in particle size and distribution, indicating the potential of this method for enhancing the application of egg white protein in the food industry.