Characterization of Flaxseed Gum/Rice Bran Protein Complex Coacervates

Effect of protein to polysaccharide ratio (3:1, 6:1 & 9:1) and total biopolymer concentration (0.1, 0.2 & 0.4) on ζ-potential, particle size and particle distribution index (PDI) of complex coacervates were investigated. Furthermore, the physical, thermal and morphological characteristics of FG, RBP, RBP-FG coacervates and cross-linked RBP-FG coacervates by sodium tripolyphosphate were surveyed. Results showed that at low concentrations of FG (9:1 ratio) and a total concentration of 0.4, the ζ-potential of coacervate was close to zero and the coacervates had the largest size revealing the greatest interaction between biopolymers. SEM results showed a porous network structure which was varied from the RBP and FG. In contrast, the cross-linked coacervates showed a fine, uniform structure with less number of pores. FTIR findings revealed that the coacervate, due to the non-covalent interaction forces, was successfully developed. The fading of the pure peaks of protein and polysaccharide in XRD diffractogram indicated the interactions between the RBP and FG, as well as the structural changes of the complex. NaTPP cross-linked coacervate was indicated a reflection of slightly increased crystallinity. However, the dried powder of coacervates was generally amorphous. According to TGA and DSC results, cross-linked coacervates exhibited the highest thermal stability amongthe single biopolymers and non cross-linked coacervate.