Structural and rheological properties of mung bean protein emulsion as a liquid egg substitute: The effect of pH shifting and calcium

The objective of this study was to develop functional egg substitutes using mung bean protein (MBP) through pH₁₂-shifting modification and calcium addition. The influence of pH₁₂-shifting and Ca²⁺ ions on emulsion stability and the physical properties of MBP-based emulsion gels were elucidated in a neutral (pH 7) composite system (7.2% MBP and 10% canola oil). Results showed that the pH₁₂-treated MBP emulsions were stable even after 5-day storage at 25 °C. The pH₁₂-shifting significantly decreased the average emulsion droplet size from 524 nm in emulsion of native MBP to 422 nm. The emulsion samples were further heated at 95 °C to induce the formation of gels. With the calcium addition of 0 or 5 mM, the pH₁₂ MBP emulsion did not form self-supporting gels. In the presence of 10–20 mM Ca²⁺, emulsion gels prepared with pH₁₂-treated MBP exhibited a uniform and compact network structure. The gel hardness, water-holding capacity, and water distribution of pH₁₂-treated MBP emulsion gels were superior to that of the native MBP samples. This study demonstrated MBP-based emulsion gels can be improved by pH₁₂-shifting treatment in combination with calcium addition, resulting in a similar texture to egg, hence, the potential to develop MBP-based egg substitutes.