Influence of NaCl on the oil/water interfacial and emulsifying properties of walnut protein-xanthan gum

Effect of NaCl concentration (0-500 mM) on the oil/water interfacial and emulsifying properties of walnut protein-xanthan gum complex (WP-XG) was investigated. In solution system, NaCl at 150-500 mM promoted the aggregation of WP-XG with a maximum hydrodynamic diameter of 553.1 nm. Compared with pure mixture, WP-XG solutions at 150-500 mM NaCl showed higher interfacial pressure and diffusion rate at the oil/water interface, and the maximum values, 18.05 mN/m and 0.431 mN m(-1) s(-0.5) respectively, were obtained at 350 mM NaCl. With a maximum dilatational modulus of 48.47 mN/m at 150 mM NaCl, higher NaCl concentration would negatively influence the interfacial dilatational properties of WP-XG. In emulsion system, NaCl decreased zeta-potential, while increased surface protein concentration. According to the CLSM graphs, NaCl would aggravate depletion flocculation which was observed in pure emulsion. Large droplets were observed at 500 mM NaCl, with significant increase in mean particle diameter (d(4,3) = 2.90 mu m). (C) 2017 Published by Elsevier Ltd.