Effects of Gum Arabic Concentration and Soy Proteins on the Flow and Viscoelasticity of their Dispersion

Abstract

The present study analyzed the flow and viscoelasticity behavior of dispersions of 15 to 45% (w/v) gum arabic, 1 to 8% (w/v) soy proteins, and of gum arabic/soy proteins mixtures. Flow of gum arabic dispersions showed Newtonian behavior, while soy protein dispersions and gum arabic/soy proteins mixtures presented non-Newtonian behavior (n < 1) of shear thinning type. Viscosity increased by 239% in the gum arabic/soy protein mixture (45/8%) compared with gum arabic/soy proteins dispersions (45/0%). The consistency coefficient (K) increased with rising gum arabic or soy proteins concentration in the dispersions. The viscoelastic behavior of mixtures with low gum arabic concentrations showed G′ > G″ values (1712% in gum arabic/soy protein [15/1%] dispersions), behaving as predominantly elastic systems (viscoelastic solids). However, at higher gum arabic concentrations (35 and 45%), the gum arabic/soy protein mixtures presented G′ < G″ values (389% for [45/8%] gum arabic/soy protein), behaving as viscose dispersions (viscoelastic liquids); this shows an antagonistic effect as gum arabic and soy protein concentrations increase, which is more evident in the rheological behavior of the studied mixtures. The interaction between polysaccharides and proteins leads to a better understanding of the rheological behavior of complex mixtures, at high concentrations, allowing these model systems to be useful in the future applications in the food industry.