Effect of pH on the formation of electrostatic complexes within admixtures of partially purified pea proteins (legumin and vicilin) and gum Arabic polysaccharides

The effect of pH on the formation of soluble and insoluble electrostatic complexes in admixtures of partially purified pea legumin (Lg) and vicilin (Vn) with gum Arabic (GA) polysaccharides was investigated by turbidimetric, surface charge and fluorometric measurements. Partial purification of the crude Lg and Vn fractions led to a shift towards higher pHs at the onset of soluble complex formation within both mixed systems, whereas the onset of insoluble complex formation was unaffected. Complexation also resulted in a pH shift corresponding to complex neutrality (zeta potential = 0 mV) to lower pH. In the case of the Vn fraction, changes to the tertiary structure were evident by a rise in fluorescence intensity upon complexation with GA relative to Vn alone, whereas no changes were found for Lg.

► Purification of proteins affected only soluble complex formation.
► Complexation of pea proteins and sub‐fractions with gum Arabic was similar.
► Pea protein’s tertiary conformation was changed upon complexation.