Improving emulsification performance of waxy maize starch by esterification combined with pulsed electric field

The development of high-performance edible particles for stabilizing gel-like Pickering emulsions has attracted increasing attention due to their high storage stability and potential in prolonging the release of intestinal drugs. In this study, a pulsed electric field (PEF)-assisted octenyl succinic anhydride (OSA)-modified waxy maize starch (WMS) was established, which could be used as an excellent Pickering emulsion stabilizer. The PEF treatment improved the esterification efficiency of WMS by disrupting its granule surface and crystalline structure to offer more sites for esterification. The degree of substitution (DS) of starch dually modified at 2.5-5.5 kV/cm was 3.0-46.9% higher than that of starch modified by the conventional method. The X-ray photoelectron spectroscopy results revealed that the OSA groups were distributed on the surface of starch granules, increasing the hydrophobicity of the surface. Among all the starch samples, the contact angle of the OSA-modified starch treated with PEF at an intensity of 4.5 kV/cm was close to 90. The dual-modified starch enhanced the amphipathic property and surface activity, indicating its potential to stabilize the formation of gel-like Pickering emulsions and increase their apparent viscosity (eta) and storage modulus (G'). Finally, increasing the starch particle concentration could facilitate the formation of gel-like emulsions by enhancing the entanglement and interaction between them.