Esterification of soy hull polysaccharides with octenyl succinic anhydride: pH-dependent structural changes and...

In this study, soy hull polysaccharides (SHP) were modified with octenyl succinic anhydride (OSA) to investigate pH-induced structural changes and stabilization mechanism at the oil-water interface. The results revealed that the modified OSA-SHP exhibited a looser network structure with larger voids, reduced surface tension. At pH 2.0-3.0 induced electrostatic interactions altered polysaccharide entanglement, promoting smaller droplets and forming a less flexible interfacial layer with high inter-chain friction. At pH 4.0-6.0, the increase in negative charge density may have promoted a more homogeneous particle distribution and led to the formation of a mechanically stronger interfacial film. Under alkaline conditions (pH 7.0-9.0), the observed formation of smaller aggregates can be attributed to the increased inter-droplet repulsive forces under these conditions. This resulted in a thinner but more rigid interfacial layer with limited molecular rearrangement, consequently leading to weaker adsorption. This study systematically reveals how OSA modification and pH govern the structural evolution of SHP, impacting the rigidity and stability of the interfacial films formed.