Preparation and characterizations of Pickering emulsions stabilized by hydrophobic starch particles

Soybean oil–in–water (O/W) Pickering emulsions were prepared using octenyl succinic anhydride (OSA) modified indica rice starch as particle stabilizers. The major factors affecting the emulsion stability were studied systematically. The rheological behaviors of the emulsions were also investigated by means of rheometer. Results indicated that the suitable parameters for the preparation of O/W Pickering emulsions stabilized by rice starch particles were selected as follows: concentration of starch particles 4.0 wt. % (degree of substitution 0.0287), soybean oil fraction 50 vol. %, pH of emulsion system 6.0–7.0. NaCl and sucrose concentrations had no obvious effect on the cream volumes of emulsions from 0 to 200 mmol/L. The rheological properties revealed that the Pickering emulsions showed a phenomenon of pseudo–plastic fluid characteristics. The elastic modulus (G′) was always higher than loss modulus (G″) at frequencies of 0.01–10 Hz. Moreover, G′ and G″ showed increasing trend with the increase in starch particle concentration. Microstructure of the Pickering emulsions showed that starch particles accumulated at the oil–water interface in the form of a densely packed layer. These results implied that an inter–droplet network probably formed, making the emulsions a gel–like behavior.