Intermolecular Interactions during Complex Coacervation of Pea Protein Isolate and Gum Arabic

The nature of intermolecular interactions during complexation between pea protein isolate (PPI) and gum arabic (GA) was investigated as a function of pH (4.30-2.40) by turbidimetric analysis and confocal scanning microscopy in the presence of destabilizing agents (100 mM NaCl or 100 mM urea) and at different temperatures (6-60 degrees C). Complex formation followed two pH-dependent structure-forming events associated with the formation of soluble and insoluble complexes and involved interactions between GA and PPI aggregates. Complex formation was driven by electrostatic attractive forces between complementary charged biopolymers, with secondary stabilization by hydrogen bonding. Hydrophobic interactions were found to enhance complex stability at lower pH (pH 3.10), but not with its formation.