Characterization and optimization of complex coacervation between soluble fraction of Persian gum and gelatin

The formation of gelatin-soluble fraction of Persian gum (SFPG) coacervates was studied as a function of biopolymers ratios (from 2:0 to 1:1 ratio of gelatin-SFPG; total concentration of 2%) and pH (from 5 to 3) through combined experimental design. Decreasing pH from 5 to 4 resulted in an increment in turbidity, from 2 to 30, then decrement up to pH 3, from 30 to 12 and SFPG increment also led to turbid solution. Methylene blue spectrophotometry and Zeta potential monitoring during complex formation were applied to confirm turbidity results. Methylene blue absorbance increased at higher amounts of SFPG and around pH 4. The coacervate phase of the suspensions showed weak viscoelastic properties. Optimal values of pH and gelatin-SFPG ratio for complex coacervation were determined to be 4.0 and 1:1, respectively. The zeta potential of complex coacervate of gelatin-SFPG was reported about -6 mV. FTIR analysis confirmed interaction between the protein and polysaccharide since new peaks of SFPG was appeared and intensity of characteristic bands of SFPG was decreased in gelatin-SFPG complex spectrum. Thermogravimetric analysis showed maximum degradation at around 250 degrees C. These findings showed that gelatin-SFPG coacervate formation is a novel facile complexion of protein- polysaccharides which can be studied for delivery of bioactive compounds.