Evaluation of structural and physicochemical properties of octenyl succinic anhydride modified sweet potato starch with different degrees of substitution.

Octenyl succinic anhydride modified sweet potato starch (OSA-SPS) were synthesized in different degrees of substitution (DS) from 0.0073 to 0.0153. Unlike sweet potato starch (SPS), two additional characteristic peaks were detected at 1,572 and 1,724 cm^-1 from the Fourier Transform-Infrared spectroscopy in OSA-SPS and their intensities were generally increased with the elevation in DS. Scanning electron microscopy and X-ray diffraction analyses revealed that the esterification did not alter the initial shape of starch granules and mainly occurred on the surface of starch pellets. In addition, OSA-SPS possessed higher transmittance, viscosity and stability, lower gelatinization temperature, and shorter gelatinization time than SPS. The changes of these properties of SPS after the esterification with OSA would be more conducive to its application in food and other fields. PRACTICAL APPLICATION: Octenyl succinic anhydride modified starch (OSAS), as a relatively novel amphiphilic surfactant, have been applied to the processing of many products due to its special hydrophilicity and lipophilicity. The structural and physicochemical properties of sweet potato starch (SPS) and octenyl succinic anhydride modified sweet potato starch (OSA-SPS) with different degrees of substitution (DS) were systematically analyzed in this research. The findings give fundamental understanding of OSA-SPS and provide a basic reference for its application in industries including food, cosmetics, textiles, and so on.