Chitosan/gum arabic complexes to stabilize Pickering emulsions: Relationship between the preparation, structure and oil-water interfacial activity

Chitosan (CS) was used as the cationic polyelectrolyte, and gum Arabic (GA) was used as the anionic polyelectrolyte to fabricate natural biodegradable CS/GA complexes. The relationships between the preparation, microstructure and interface activity of CS/GA complexes were explored, with aiming to tune the interface activity of CS/GA complexes. FTIR confirmed that CS and GA was combined mainly through electrostatic interaction. CS/GA mass ration, ionic strength and pH significantly affected the reaction between CS and GA and the interface activity of CS/GA complexes. All complexes were in spherical shape but with different size and aggregation degree. Low CS/GA ratio improved the yield and interface activity of CS/GA complexes. The presence of NaCl reduced the yield and interface activity of CS/GA complex. The CS/GA complexes obtained beyond the pKa of CS showed higher yield, lower interface tension and higher emulsion capacity. It was mainly related to the highest yield of particles including the CS/GA complexes and single CS particles at this pH. However, the complex prepared at pH 5.0 stabilized- Pickering emulsion showed higher stability. This suggested that the pure CS/GA complexes possessed higher interface activity than single CS particles.