Preparation and Characterization of OSA-modified Tapioca Starch-based Pickering Emulsion

To investigate the effects of different preparation conditions on starch-based Pickering emulsions, Pickering emulsions were prepared using octenyl succinic tapioca starch (OSTS) as a solid particle emulsifier. The effects of OSTS additions (3.0%, 3.5%, 4.0%, 4.5%, 5.0%) and oil phase volume fractions (40%, 45%, 50%, 55%, 60%) on the properties of the emulsions were investigated by using the emulsion particle sizes, rheological properties, microstructures, and storage stabilities as the indexes. The effects of different ionic strengths (100, 200, 300, 400, 500 mmol/L) and pH levels (2, 4, 6, 8, 10) on the particle size and stability of the emulsion were also examined. Results showed that the particle size of the emulsion was the smallest, 3.59 μm, at 5% OSTS addition and a 50% volume fraction of the oil phase, and the emulsion did not show delamination after 60 d of storage. It also showed that an elastic gel network structure was formed inside the emulsion, and that its viscosity and gel strength increased with increasing OSTS addition and oil phase volume fraction, leading to an enhanced deformation resistance. Furthermore, high concentrations of salt ions (NaCl concentration ≥500 mmol/L) and strong alkalis (pH≥10) significantly increased the emulsion particle size (P<0.05) and decreased its stability. However, under the conditions of 5% OSTS addition, 60% oil phase volume, 100 mmol/L NaCl concentration, and a pH of 6, the emulsion exhibited good stability.