High internal phase emulsions stabilized by physically modified mung bean protein isolates under different pHs

This research explored the impact of modified mung bean protein isolates (MBPIs) on the physicochemical, rheological, and structural properties of 70% oil-containing high internal phase emulsions (HIPEs). MBPIs (4% protein concentration) were subjected to heating (90 °C for 2 h) or sequential heating/ultrasonication (20 kHz, 120 W for 10 min) at different pHs (2, 7, and 10). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of modified MBPIs confirmed heat treatment at pH 2 hydrolyzed MBPI, unlike MBPIs heated at pH 7 and 10. Sequential heating/ultrasonication significantly reduced particle size, improved solubility and surface hydrophobicity of MBPIs, resulting in smaller droplet size and enhanced gel-like properties of HIPEs. Transmission electron microscopy revealed that sequentially heated/ultrasonicated MBPIs in the oil–water interface existed in a fibrillar or randomly aggregated structure at pH 2, a randomly aggregated structure at pH 7, and a particulate aggregated structure at pH 10. Overall, these structural modifications at varied pH conditions influenced MBPI adsorption at the HIPE droplet interface, impacting rheological features and promoting the potential use of protein-stabilized HIPEs across diverse applications.