Complex coacervation between oak protein isolate and gum Arabic: optimization & functional characterization

Abstract

In this research, complex coacervation between oak protein isolate (OPI) and gum arabic (GA) at different pH values (7.0–1.6) and mixing ratios (8:1 to 1:8 protein: polysaccharide), and a constant biopolymer concentration (0.125% w/w) was studied by turbidimetric analysis. The findings revealed that the pH = 3.2 and 4:1 mixing ratio were the optimum conditions for electrostatic complex formation. The functional properties (e.g., solubility, surface hydrophobicity, capacity of water and oil absorption, foam formation, and emulsifying properties) of the OPI-GA complexes were better than OPI. The FTIR spectra revealed that the complex coacervation between the amine groups of OPI and the carboxyl groups of GA caused the formation of the coacervate, with hydrogen bonding also being involved. The results of DSC and TGA showed that the complex coacervate had better thermal stability in comparison with OPI and GA.

Keywords

• gum arabic
• oak protein isolate
• electrostatic interaction
• complex coacervation
• zeta potential
• solubility
• foaming
• emulsions
• surface hydrophobicity