Mechanism Of The Influence Of Soybean Saponin/Protein Interaction On Its Gas-Water Interface Properties

Soyasaponin and soy protein are the two major by-products of soybean oil processing and have the potential to replace synthetic and semi-synthetic surfactants.In this study,soy glycinin(11S)or β-conglycinin(7S)-soyasaponin complex system were characterized by endogenous tryptophan fluorescence spectroscopy,pyrene fluorescent probe spectroscopy,dynamic surface tension,and surface film expansion rheology.The foaming characteristics of these two systems were analyzed.The results showed that the composite system formed a composite interfacial layer.Under the low soyasaponin concentration(0.1-0.5 mg/mL),the interface layer was composed of protein(11S,7S)dominates,at high soyasaponin concentration(2 mg/mL),the nature of the interface layer was dominated by soyasaponin.11 S,7S in the complex system solution and soyasaponin were mainly combined by hydrophobic interaction.At the medium soyasaponin concentration(0.5-1 mg/mL),the secondary and tertiary structure of 7S and 11 S were changed.They were easier to adsorb on the composite interface,promoted the formation of the composite layer of protein and soyasaponin,and the composite layer showed certain elasticity and viscosity.Compared with protein or soyasaponin alone groups,those mixed systems showed better foaming property.This study evaluated the possibility of the soy protein-soyasaponin composite system as a natural surfactant,and studied the correlation between the microscopic behavior of the gas-water interface and macroscopic characterization,which is a natural,green and healthy functional ingredient.Further application in the food industry provides a relatively scientific support.