Steady shear rheological properties, microstructure and stability of water in water emulsions made with basil seed gum and waxy corn starch or high pressure-treated waxy corn starch

The water in water (W/W) emulsions were prepared by mixing basil seed gum (BSG) with waxy corn starch (WCS) or high pressure-treated waxy corn starch (HWCS) at different concentrations. Increasing the concentration of WCS or HWCS increased the zeta potential, consistency index, infinite shear viscosity, and apparent viscosity, while it decreased the Z-average droplet size, polydispersity index, separation index, and flow behavior index of the W/W emulsions. After increasing the concentration of WCS and HWCS, the micrographs captured by an optical microscope indicated that the number of follicular droplets increased more than individual droplets. However, coalescence did not occur due to electrostatic repulsion. When the concentration of WCS and HWCS was increased from 0.5 to 2 wt% (at a constant concentration of 0.25 wt% and 0.2 wt% of BSG, respectively), the consistency index of the emulsions was increased significantly (p < 0.05) from 0.109 to 0.436 Pa. sn and from 0.032 to 0.743 Pa. sn, respectively. The results simply revealed the capability of 0.2 wt% BSG+ 0.5, 1, or 2 wt% HWCS and 0.25 wt% BSG+ 0.5, 1, or 2 wt% WCS for being utilized as stable W/W emulsions; these emulsions were stable for at least a week.