The formation, structural and rheological properties of emulsion gels stabilized by egg white protein-insoluble soybean fiber complex

Abstract

In this work, the structural and interfacial characteristics of egg white protein-insoluble soybean fiber (EWP-ISF) complex, as well as the effects of the EWP-ISF ratio and oil volume fraction ( φ ) on the formation of emulsion droplet-aggregated gels were investigated. EWP was adsorbed onto the surface of ISF matrix at pH 3.2 via electrostatic and hydrogen-bonding interactions. The contact angle significantly increased from 119.3° to 131.5° ( p < 0.05) as the EWP-ISF ratio changed from 1:0 to 1:2, simultaneously, the adsorption of EWP-ISF complex at the oil-water interface produced a visible interfacial film. At lower φ of 0.2–0.3, as the EWP-ISF ratio decreased from 2:1 to 1:2, the droplets became finer and the gel-like structure was strengthened; additionally, the relaxation time ( T 23 ) significantly decreased from 622.257 ms to 219.639 ms ( p < 0.05), implying the conversion of movable water to bound water. At a higher φ of 0.4–0.5, the droplets were densely packed through bridging flocculation and interactions between droplets and the gel network. Accordingly, the emulsion droplet-aggregated gels stabilized by EWP-ISF presented high elastic modulus and yield stress, as well as excellent thixotropic recovery. • The emulsibility of egg white protein-insoluble soybean fiber (EWP-ISF) was raised. • EWP adsorbed to the ISF surface via electrostatic attraction and hydrogen-bonding. • The adsorption of EWP-ISF at oil-water interface formed a visible interfacial film. • EWP-ISF emulsion gels had higher yield stress and superior thixotropic recovery.