Ethanol induced the gelation behavior of duck egg whites

Abstract

In this study, changes in the gel properties, microstructure, and molecular interaction force during the formation of duck egg white (EW) gel induced by ethanol were investigated. Results showed that the viscosity of the EW increased with increasing ethanol concentration and treatment time. The hardness and cohesiveness of the formed gel increased first with prolonged treatment time, then decreased slightly, and finally almost kept stable. The increase in the centrifugal water holding capacity and transformation of immobile and free water into bound water was related to the increasingly compact structure of the gel network. The force that maintained the gel network was mainly ionic bond (~45%) and disulfide bonds (~45%). The hydrogen bond and hydrophobic interaction were extremely low. SDS-PAGE results showed that the ethanol-treated EW proteins were degraded to some extent, but the bands did not significantly change with time. The negative charge content and surface hydrophobicity of the protein increased continuously. The secondary structure of the EW gel showed that the mutual transformation of β-sheet, random coil, α-helix, and β-turn resulted in the good texture characteristics of the gel. The ethanol treatment promoted the disulfide bond cross-linking of the duck EW proteins, and the network structure of the EW gel became increasingly compact, resulting in a series of changes in the water retention and binding water content of the gel. Protein aggregation also occurred, which enhanced the hardness, springiness, and cohesiveness of the duck EW gel.