Effects of pH, protein:polysaccharide ratio, and NaCl-added concentration on whey protein isolate and soluble soybean polysaccharides electrostatic-complexes formation
Daniela E. Igartúa, Darío M. Cabezas, Gonzalo G. Palazolo
Abstract
In the present work, the interaction between whey protein isolate (WPI) and soluble soybean polysaccharide (SSPS) was studied as a function of pH (7.0 to 2.0), WPI:SSPS mass ratio (1:1 to 10:1), and NaCl-added concentration (0 to 100 mM). The interaction was analyzed by ζ-potential, turbidity, and state diagrams. Then, WPI-SSPS complexes were obtained in the optimized conditions of pH (4.0 to 3.5), WPI:SSPS ratio (2:1 to 6:1), and NaCl-added concentration (0 to 100 mM). The complexes were characterized by ζ-potential, particle size, and physical stability in a factorial 3 × 3 design with analysis by response surface methodology. This methodology showed that the characteristics of the WPI-SSPS complexes are modulated by the modification of the studied parameters. By lowering the pH, the complexes showed a ζ-potential closer to 0 and higher physical stability. By decreasing the WPI:SSPS ratio, the complexes showed more negative ζ-potential. Finally, by increasing the NaCl concentration, the complexes showed negative ζ-potential but an increment of mean particle size and polydispersity index. Data obtained in this work is useful to design WPI-SSPS complexes with specific characteristics of size, charge, and physical stability. These complexes could then be applied in food, medicinal or cosmetic matrices for different purposes.