Formation and Characterization of β-Lactoglobulin and Gum Arabic Complexes: the Role of pH.

Protein-polysaccharide complexes have received increasing attention as delivery systems to improve the stability and bioavailability of multiple bioactive compounds. However, deep and comprehensive understanding of the interactions between proteins and polysaccharides is still required for enhancing their loading efficiency and facilitating targeted delivery. In this study, we fabricated a type of protein-polysaccharide complexes using food-grade materials of beta-lactoglobulin (beta-Lg) and gum arabic (GA). The formation and characteristics of beta-Lg-GA complexes were investigated by determining the influence of pH and other factors on their turbidity, zeta-potential, particle size and rheology. Results demonstrated that the beta-Lg and GA suspension experienced four regimes including co-soluble polymers, soluble complexes, insoluble complexes and co-soluble polymers when the pH ranged from 1.2 to 7 and that beta-Lg-GA complexes formed in large quantities at pH 4.2. An increased ratio of beta-Lg in the mixtures was found to promote the formation of beta-Lg and GA complexes, and the optimal beta-Lg/GA ratio was found to be 2:1. The electrostatic interactions between the NH3+ group in beta-Lg and the COO(-)group in GA were confirmed to be the main driving forces for the formation of beta-Lg/GA complexes. The formed structure also resulted in enhanced thermal stability and viscosity. These findings provide critical implications for the application of beta-lactoglobulin and gum arabic complexes in food research and industry.