Ultrasonic effect on the octenyl succinate starch synthesis and substitution patterns in starch granules

Octenyl succinate starch (OS-starch) was prepared with ultrasonic-assisted treatment. The substitution patterns in starch granule was estimated by acid hydrolysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, confocal laser scanning microscopy and chemical surface gelatinization. The pasting properties of starch derivatives were studied by Brabender pasting analyzer. Results showed that ultrasound could reduce reaction time and improve the reaction efficiency over the control by 15–20%. Substitution pattern with the OS-groups located predominantly in the amorphous domains and on the granule surface with a surface effect that is more pronounced than in acetylation reactions. Ultrasonic treatment during octenyl-succinylation results in a somewhat less pronounced surface effect. Compared with OS-starch made by traditional method (OSS), OS-starch prepared under ultrasonic condition (UOSS) has slightly higher pasting temperature, break down and setback values, lower peak viscosity, hot paste viscosity and final viscosity.