Effect Of Soy Polysaccharide/Protein Structures Induced By PH On The Interfacial Stabilization Mechanism

Proteins and polysaccharides are widely used as the emulsifiers and stabilizers in food emulsions,and the ineraction between them in food systems,which plays an critical role on the food emulsifing systems.The study explored the pH-induced interaction and conformational conversion of soy protein isolated?SPI?and soy hull polysaccharide?SHP?in phase solutions,illustrated the sdsorption behavior of them at the oil/water interface and revealed the stabilization mechanism finally.And this work aimed to improve the stability of emulsified foods and provide the theoretical basis for exploiting the novel food emulsifiers to some extent.The major results are as below:1.pH had a significant effect on the interaction and protein's conformational conversion of SPI and SHP at phase solutions,oil/water interface and emulsifing systems,respectively.Moreover,the interaction between SPI and SHP were the electrostatic interactions and hydrogen bond majorly,and there were still the hydrophobic force,van der Waals force and other intermolecular and intramolecular interactions as well.2.The pH-induced SPI/SHP complexes improved and enhanced the adsorption properties of SPI at the oil/water interface and interfacial stability of emulsions.3.At the acidic conditions,the electrostatic attraction and hydrogen bond between SPI and SHP played a dominant role.When the pH was 3.0-5.0,the electrostatic complexes was formed by the–COO^-of SPI and–NH³⁺of SHP at the amide II band(¹543 cm^-1),which enhanced the diffusion rate at the oil/water interface and the content of?-helix for SPI,improved the hydrophibicity and surface activity of the amino acid residues on the peptide chains of protein.Moreover,the formed double interfacial membrane restricted the movement of oil droplets and inhibited the aggregation of droplets,decreased the interfacial tension and particle size,formed the more uniform size and distribution of droplets,presented the excellent rheological properties and enhanced the interfacial stability of SPI/SHP emulsions.Above all,at pH 3.0-9.0,especially at pH 3.0-5.0,the SPI/SHP electrostatic complexes induced by pH could be used to stabilize the food oil-in water?O/W?emulsified systems,and provide some therotical basis for the formulations of preparaing the novel emulsifing foods.