Oil-water Interface Behavior And Emulsion Stability Of Soyasaponin-7S/11S Mixture

As two main by-products of soybean processing,soyasaponin,soybean protein and their mixture have potential to replace semi-synthetic and artificial surfactants.In this study,soyasaponin(Ssa),glycinin(11S),and ?-conglycinin(7S)are used as research objects.Through the study of dynamic interfacial tension and interfacial expansion rheological properties,adsorption behavior of the 7S/11S-Ssa mixture at the oil-water interface was characterized;particle size distribution of emulsion formed by mixture,interface protein concentration,?-potential,and stability of the emulsion were investigated,The relationship between oil-water interface behavior and the long-term stability of emulsion was discussed;the effects of two environmental factors(pH and temperature)on the stability of composite emulsion were investigated.Main conclusions are as follows:1.Dynamic drop analysis and multiple light scattering techniques were used to study the oil-water interface behavior,emulsion characteristics,and stability of 7S-Ssa mixture.Results showed that the interface adsorption and expansion rheological behavior of 7S-Ssa composite system was mainly dominated by 7S at lower Ssa concentrations(0.05%),but the addition of Ssa significantly improved the emulsification ability of mixture.With the addition of Ssa concentrations(0.1%-0.75%),7S and Ssa showed a synergistic effect in reducing interfacial tension.At high Ssa concentration(0.75%),particle size was the smallest and its distribution was uniform.Emulsions exhibited a fine formation ability and long-term stability after 42 d,which was believed to be the better response to external deformations.2.The oil-water interface behavior,emulsion characteristics and stability of the 11S-Ssa mixture were compared with the 7S-Ssa mixture to study the effect of protein structure differences on the emulsification characteristics of the mixture.Results showed that interfacial tension and rheological properties of 11S-Ssa mixture are similar to 7S-Ssa mixture,but particle size and stability of 7S-Ssa composite emulsion are smaller.The addition of Ssa(0.05%-0.5%)improved the emulsification ability of mixture,and composite emulsion showed good long-term stability after 42 d.3.The effects of typical environmental factors(pH,temperature)on the stability of 11S-Ssa composite emulsion were studied.Results showed that stability of mixture was poor at pH 4.5,and a more serious delamination phenomenon appeared.After further lowering the pH,stability of emulsion improved,and Ssa had a certain effect on improving the acid resistance of the composite emulsion.Stability of mixture was reduced after heat treatment,but the stability of composite emulsion with Ssa was still better than the emulsion stabilized by 11S alone.