Gum Arabic−Chitosan Complex Coacervation

Abstract

The formation of electrostatic complexes of gum Arabic (GA) with chitosan (Ch), two oppositely charged polysaccharides, as a function of the biopolymers ratio (R_GA/Ch), total biopolymers concentration (TB_conc), pH, and ionic strength, was investigated. The conditions under which inter-biopolymer complexes form were determined by using turbidimetric and electrophoretic mobility measurements in the equilibrium phase and by quantifying mass in the precipitated phase. Results indicated that optimum coacervate yield was achieved at R_GA/Ch = 5, independently of TB_conc at the resulting pH of solutions under mixing conditions. High coacervate yields occurred in a pH range from 3.5 to 5.0 for R_GA/Ch = 5. Coacervate yield was drastically diminished at pH values below 3.5 due to a low degree of ionization of GA molecules, and at pH values above 5 due to a low solubility of chitosan. Increasing ionic strength decreased coacervate yield due to shielding of ionized groups.