Comparative Study on Stability of Emulsion and Foam Stabilized by Rambutan Seed Protein, Rambutan Seed Protein with High Intensity Ultrasonication Modification, and Soy Protein

Rambutan (Nephelium lappaceum) seed proteins (RSP) with/without high intensity ultrasonication modification were used as natural emulsifiers.Emulsions were prepared by using RSP powder of 1% (w/w) and corn oil of 5% (w/w).Emulsions prepared by rambutan seed protein with high intensity ultrasonication modification (US protein) showed high heat stability at 60 -90 °C and the heat stability of emulsions was comparable to emulsions prepared by soy protein (SP).Heated emulsions prepared by rambutan seed protein without high intensity ultrasonication modification (No-US protein) contained more bridging flocculation than US protein emulsions.US protein emulsions and No-US protein emulsions exhibited high stability against coalescence after freeze thawing while SP emulsions transformed into emulsion gel.US protein emulsions and No-US protein emulsions displayed relatively similar surface charge characteristics and microstructure in varied pH (2 -12) and salt concentrations (100 -300 mM).Foam prepared by US protein and No-US protein powder of 1% (w/w) had comparable capacity and higher capacity than SP foam.No-US protein foam had comparable stability as SP foam and higher stability than US protein foam.