Regulating the interfacial behavior of diacylglycerol emulsions via non-covalent assembly of soluble soybean polysaccharide and soy protein isolate complexes.

Soluble soybean polysaccharide (SSPS) demonstrates distinct structure and function in forming non-covalent complexes with soy protein isolate (SPI) and stabilizing diacylglycerol (DAG) emulsions. The complexation between SPI and SSPS was predominantly driven by non-covalent interactions, specifically electrostatic forces and hydrogen bonding. SSPS induced SPI unfolding, increased secondary structure disorder, molecular flexibility, particle size and surface charge. At 0.1% SSPS, SSPS cross-linked SPI, exposing hydrophobic groups and increasing surface hydrophobicity and amphiphilicity. However, with 0.2% SSPS, the increased coverage began to shield these hydrophobic groups, reducing surface hydrophobicity. With 0.3%-0.4% SSPS, SSPS formed a continuous hydrophilic network that improved stability and viscosity via steric hindrance, while competitively adsorbing onto the DAG interface and becoming the dominant stabilizer. Thus, SSPS acts as a structural modulator that governs SPI complexation and competitively stabilizes DAG emulsions, utilizing DAG's amphiphilic hydroxyl groups to optimize interface performance for functional lipid use.