Influence of pH fractionation and salt on Bambara protein–gum arabic interaction and insoluble complex formation

Proteins exhibit remarkable interaction with polysaccharides to form complexes with novel functionality. Nevertheless, the formation of insoluble complexes close to the protein isoelectric point (pI) results in protein–protein interference, low coacervates yield, and limited application in acidified food systems. Hence, pH fractionation with salt was used to extract Bambara groundnut protein to induce a shift in optimum pH (pHopt) of insoluble complexes formed with gum arabic, ultimately improving protein and coacervates yields. Turbidimetric analyses were employed to monitor the interaction between Bambara groundnut protein and gum arabic. Protein isolates from optimised fractionation conditions and insoluble complexes were characterised. The most effective fractionation condition was achieved at pH 2.95, 0.28 M NaCl, producing a substantial pHopt shift to 3.4. This shift was associated with the formation of spherical microparticle complexes and an impressive 70% coacervate yield. Changes in patterns of protein–gum arabic interaction were associated with an increased content of β-sheet, enrichment of legumin subunits, and basic amino acids of the isolate. This approach successfully shifted the formation of insoluble complexes towards a high-acid pH environment, notably away from the pI. Findings from this study create a prospect for future utilisation of pulse grain protein-gum arabic complexes in acidic beverage development.