Concentration-Dependent Modulation of Fibrillated Egg White Protein by γ-Cyclodextrin: Structural, Emulsifying, and Rheological Properties of Oil-in-Water Emulsions

Abstract

Fibrillated egg white protein (FEWP) has promising emulsifying functionality, whereas excessive association may restrict the organization of freshly prepared emulsions. This study examined the concentration-dependent effects of γ-cyclodextrin (γ-CD; 0.5%, 1%, and 2%, w/v) on 3% (w/v) FEWP dispersions and the resulting oil-in-water emulsions. Relative to native egg white protein (NEWP), redispersed FEWP showed a smaller apparent hydrodynamic diameter (36.56 vs. 371.97 nm). γ-CD caused only minor changes in particle size and a non-monotonic intrinsic-fluorescence response. Among the γ-CD levels tested, 1% produced the highest intrinsic fluorescence intensity, emulsifying activity index (2.56 m2/g), and emulsion stability index (207.87 min). In the observed microscopic fields, this formulation contained fewer conspicuous large droplets and a visually more uniform spatial distribution than the other FEWP-γ-CD formulations. It also moderated progressive microscopic immobilization and maintained elastic-dominated, shear-thinning, and partially recoverable behavior. Increasing γ-CD to 2% reduced emulsifying performance and bulk structural connectivity. Thus, 1% γ-CD provided the most favorable combination of short-term emulsifying and rheological properties among the concentrations examined.