Ultrasonic‐Assisted Fabrication of SPA–SSPS Composite Particles: Role of Mass Ratio in Modulating Structural and Emulsifying Properties

This study investigated the influence of mass ratios on the properties of soybean peptide aggregate (SPA)-soluble soybean polysaccharide (SSPS) composite particles (CPs) fabricated under ultrasonic assistance. The physicochemical and emulsifying properties of CPs were systematically evaluated. Results indicated that the mass ratio played a critical role in determining CPs characteristics. Increasing SSPS content initially led to an enlargement in particle size, followed by a subsequent reduction. Both ζ-potential and three-phase contact angle (θ) decreased with higher SSPS content, with a θ of 87.26° observed at a 1:1 ratio. CPs with SPA-SSPS ratios of 3:1 and 2:1 exhibited lower emulsifying activity and stability compared to SPA alone, whereas ratios between 1:1 and 1:3 demonstrated significantly enhanced emulsifying performance. Mechanistic studies revealed that nanoparticle formation was primarily driven by electrostatic interactions and hydrogen bonding, as confirmed by ζ-potential and Fourier-transform infrared spectroscopy analyses. Atomic force microscopy further indicated the structural encapsulation of SPA by SSPS. Among the tested ratios, the emulsions stabilized by CPs with a 1:1 ratio displayed the smallest droplet size, highest viscosity, and maximal free fatty acid release rate, alongside improved viscoelastic properties (G' and G″) and phase stability. However, higher SSPS ratios were associated with increased free radical content. PRACTICAL APPLICATIONS: These findings provide new insights into the role of mass ratios in modulating the functional properties of SPA-SSPS CPs and offer a promising strategy for developing high-performance Pickering emulsifiers in food and pharmaceutical applications.