Phase separation behavior of flaxseed gum and rice bran protein complex coacervates

Abstract

Coacervates were prepared with rice bran protein (RBP) and flaxseed gum (FG) solutions. Structural transition during cocervate formation were evaluated by spectrophotometric, ζ-potential and light scattering as a function of pH (7.0–2.0), total biopolymer concentration (0.1, 0.2 and 0.4%) and protein to polysaccharide ratio (RBP/FG, R = 3:1, 6:1 and 9:1). Moreover, the phase transition of RBP/FG complex coacervate system was studied by monitoring the absorbance profiles as a function of time. The optimum ratio of RBP/FG for complex coacervation was found to be 9:1. The critical pH values associated with the formation of soluble (pHc) and insoluble (pHφ1) complexes at the optimum RBP/FG ratio were found to be 6.0 and 5.3, respectively. The maximum interaction, the highest optical density (OD600), was found at pH = 4.0. The instability and dissolution of RBP/FG complex coacervates initialized at pH = 2.0. Particle size distribution of RBP/FG (R = 9:1, CT = 0.4.%) obtained by dynamic light scattering (DLS) at critical pH values, provided further insight into the segregative and associative processes during complex coacervation. The findings can be contributed to the development of RBP/FG complex coacervates as delivery system for volatile aroma or bioactive compounds.