Effect of pH and sodium ion on the interfacial adsorption abilities and emulsion stability of soy hull polysaccharide.

AbstractTo investigate the effect of ionic strength and pH on the interfacial adsorption capacity and emulsion stability of soy hull polysaccharide (SHP), a series of SHP emulsions with 10% oil content was prepared with 0–0.30 mol/L Na+ at pH 3.0 and 5.0. The results of droplets size, zeta potential, dilatational rheological, and cryo-scanning electron microscopy analyses showed that the droplets of the emulsion at pH 3.0 were smaller and the system was more stable than at pH 5.0, and Na+ effectively shielded the negative charge on the SHP surface, leading to more SHP adsorption to the interface and increasing viscosity; whereas too much Na+ weakened the repulsive forces between droplets, making it easier for the droplets to merge with each other and causing emulsion destabilization. The best emulsification capacity of SHP was achieved at pH 3.0 with 0.10 mol/L Na+, in which 58.62 ± 0.49% SHP would adsorb to the interface, and kept high zeta potential of interface with −30.00 ± 0.27 mV. Meanwhile, the emulsion prepared under this condition had good storage stability and exhibited small droplet size of 2.425 ± 0.004 µm after 30 days. In conclusion, above indicators demonstrated that SHP-stabilized emulsions were influenced by pH and Na+, this provides theoretical and practical support for selecting the most suitable acid-base and ionic environment to prepare food emulsion by SHP, or other anionic polysaccharides. [ABSTRACT FROM AUTHOR]