Effect of pH on physicochemical and storage stabilities of succinylated rice glutelin emulsion

This study investigates the effects of different pH conditions on the physicochemical and storage stabilities of O/W emulsions stabilized by succinylated rice glutelin (S-RG), with whey protein isolate (WPI) utilized as a control. Emulsions were prepared at pH 3-11 and assessed over 15 days via particle size, zeta potential, rheology, microscopy, centrifugal stability, creaming index (CI), and oxidative markers (POV, TBARS). S-RG emulsions exhibited optimal stability at pH 9, with the smallest droplet size (343.73 ± 3.25 nm), highest absolute zeta potential (-62.83 ± 0.85 mV), minimal CI (near 0 %) and highest viscosity, indicating excellent resistance to phase separation. At pH 5, S-RG showed superior stability compared to WPI, with lower CI and smaller particle. Oxidative stability was highest at pH 7 (POV: 22.04 mmol/kg; TBARS: 16.03 mg MAD/kg). These results demonstrate that S-RG forms highly stable emulsions under neutral to alkaline conditions, outperforming WPI, and holds strong potential as a sustainable, plant-based emulsifier for diverse food applications.