Polysaccharide type and concentration affect nanocomplex formation in associative mixture with β-lactoglobulin

•Formation of initial soluble complexes independent from polysaccharide type.•Both contributions of charge regulation and positive patches in complexation.•Formation of stable nanocomplexes at higher polysaccharide to protein weight ratio.•Wrapping phenomenon in both linear and branched polysaccharides-protein complexes.

The main objective of this work was to investigate the effects of polysaccharide type (gum Arabic, GA and/or carboxymethyl cellulose, CMC) and concentration (0-0.2% (w/w)) on the electrostatic interactions with β-lactoglobulin (BLG). Biopolymer interaction was studied using turbidimetric analysis, dynamic light scattering (DLS), electrophoretic mobility and relative viscosity measurements. Complexes were developed at pH values below the isoelectric point (pI) of BLG. Increasing polysaccharide concentration increased the stability of nanocomplexes through increasing the negative charges carried by complexes. The differences between GA and CMC were attributed to the polysaccharide structure (linear or branched chains), charge density and flexibility. Phase contrast optical microscopy showed that complexation was of nucleation and growth type mechanism. Relative viscosity measurements confirmed that wrapping phenomenon occurred in both associative mixtures.