Physicochemical, interfacial and emulsifying properties of insoluble soy peptide aggregate: Effect of homogenization and alkaline-treatment

The physicochemical, interfacial and emulsifying properties of insoluble soy peptide aggregate (ISPA) modified by homogenization and alkaline-treatment (pH10, pH12) were studied in this paper. Homogenization and alkaline-treatment improved the content of hydrophobic amino acids of ISPA, promoting the surface hydrophobicity (H0), decreasing the hydrodynamic diameter (DH) and ζ-potential, finally enhanced the solubility and oil holding capacity (OHC). Compared to ISPA modified at pH10, ISPA modified at pH12 exhibited lower interfacial pressure (π) but higher viscoelastic modulus (E). Emulsions stabilized by modified ISPA had lower ζ-potential, smaller d4,3 and flocculation index (FI), and better stability than untreated ISPA. It was noticed that homogenization pretreatment had a synergistic effect with alkaline treatment on the improvement of emulsifying property. The effects of pH12 on the physicochemical properties of ISPA were more significant than pH10 possibly referred to the disrupting of intramolecular interaction, showing better solubility and emulsifying property. In summary, the emulsifying properties of modified ISPA were even better than that of commercial SPI, indicating that ISPA has the potential to be a good emulsifier in food industry.