Insights into structure-rheology relationships in Pickering emulsions stabilized by gliadin-citrus pectin complex...

In this study, citrus pectin was used to modify gliadin to prepare complex particles (GCP), and GCP roles in influencing emulsion formation by adjusting pH (3-7) and gliadin/citrus pectin ratio (1:0-1:0.1) was explored. Compared with gliadin particles, the instability of emulsion stabilized by GCP could be improved at pH 3.0-4.0, and GCP could form smaller droplet size of emulsions at pH 5.0-7.0. Under the selected conditions of pH 4.0 and 7.0, the GCP at 1:0.05 had tuned near neutral wettability in comparison of other ratios. Furthermore, the formation mechanism of GCP at 1:0.05 revealed the stabilizing impact on the correlation between structure and emulsions with different GCP concentrations (C_p, 2% ∼ 10%, w/w) and oil phase contents (φ, 20% ∼ 70%, w/w). Exponents (n and m), which characterize the relationship between C_p and φ with respect to the storage modulus (G'), were determined by applying power-law eqs. (G' ∼ Cⁿ and G' ∼ φ^m), respectively. The network strengths of Pickering emulsions stabilized by GCP particles had varying degrees of dependence on C_p and φ. The crossover point γ_co serves as a critical indicator of the emulsion structure's ability to resist deformation. For low oil-phase content (20% ∼ 30%, v/v), the stress required for γ_co showed a notable rise as C_p increased. In the range of medium oil-phase content (40% ∼ 60%, v/v), the stress required for γ_co rose with the GCP concentration increased, but the rate of increase decreased slightly compared to that of the low oil. In the range of high oil-phase content (70%, v/v), the required stress at the crossover-point decreased with increasing particle concentration.