Preparation and characterization of soybean Protein isolate/chitosan/sodium alginate ternary complex coacervate phase

Abstract

To improve morphological structure and stability of soy protein isolate - chitosan coacervate, a soy protein isolate-chitosan-sodium alginate ternary complex coacervate phase was successfully constructed by adding sodium alginate. The ζ -potential and turbidity data showed that soy protein isolate, sodium alginate, and chitosan interacted with each other in the pH range 5.0–7.0. The highest ternary coacervate yield was obtained at soy protein isolate/sodium alginate ratio 12:1 (g/g), soy protein isolate/sodium alginate:chitosan ratio 4:1 (g/g), pH 6.5, and total biopolymer concentration of 5 g/L. The viscoelastic properties and microstructure were also studied using rheology, fourier transform infrared spectroscopy, texture profile analysis, and scanning electron microscopy, which indicated that the ternary coacervates prepared in pH 5.5, 6.0, and 6.5 had a viscoelastic solid behavior (storage moduli between 12,600 and 35,000 Pa; loss moduli between 3440 and 10,000 Pa) with honeycomb porous network structures. The ternary coacervate prepared at pH 6.5 was more compact and clearly porous. The stability of the ternary complex coacervate phase to pH and ionic strength slight increased. The in situ cross-linking of sodium alginate can improve the structure properties of ternary coacervates, which may provide a new carrier to incoporate bioactive ingredients into food products.