Viscoelasticity of olive oil/water Pickering emulsions stabilized with starch nanocrystals

The olive oil-in-water Pickering emulsions stabilized with starch nanocrystal (SNC) were prepared for the morphological and rheological studies. Different kinds of shear flows were applied and the viscoelastic responses of emulsions were detected in terms of SNC concentrations (0.2-2.0 wt%) and surface acetylation levels (0.11-0.41 degrees of substitution). The results show that the emulsifying capacity of SNC is improved evidently after surface acetylation due to decreased surface hydrophilicity of SNC and to enhanced electrostatic repulsive effect during emulsification, which is evidenced by the gelation behavior in small amplitude oscillatory shear (SAOS) flow. The modulus and viscosity of the emulsion with acetylated SNC increase by about two orders of magnitude as compared to those of the emulsion with pristine one. The former even shows weak overshoot behavior during large amplitude oscillatory shear (LAOS) flow. This work provides valuable information on motivating development of the Pickering emulsions using SNC as particle emulsifier.