Chitin nanofiber-stabilized pickering emulsion interacting with egg white protein: Structural features, interfacial properties, and stability

Abstract

The application of chitin has significantly expanded, particularly in the formulation of protein-based complexes stabilized by electrostatic interactions, which are crucial in the development of Pickering emulsions. This study systematically investigates how variations in pH affect the molecular structure, interfacial properties, and emulsifying performance of egg white protein (EWP) complexes with chitin nanofibers (ChNFs). The findings reveal that electrostatic interactions between ChNFs and EWP substantially influence the dispersion and morphology of the complexes across a pH range of 2.0–9.0. Spectral analysis indicates that the incorporation of ChNFs leads to a slight reduction in surface hydrophobicity and fluorescence intensity of EWP, enhancing the protein's structural flexibility. Additionally, adsorption kinetics and dilational viscoelasticity measurements demonstrate that ChNFs significantly increase EWP's equilibrium interfacial pressure (up to 25 mN/m) and viscoelastic modulus, indicating improved stability at the oil-water interface. Notably, emulsions stabilized by EWP/ChNF complexes at pH values between 5.0 and 7.0 exhibit a more uniform droplet size (approximately 200 nm) and enhanced stability, with turbidity measurements reaching maximum values of 0.85. These results underscore the potential of chitin nanofibers as sustainable emulsifiers in food applications, providing a viable alternative to synthetic emulsifiers.