Preparation and properties of octenyl succinic anhydride modified early indica rice starch

Octenyl succinic anhydride (OSA) modified early indica rice starch was prepared in aqueous slurry systems and the major factors affecting the esterification were investigated systematically. The physicochemical properties of the products were determined by means of Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction and Rapid Visco Analyser (RVA). The results indicated that the suitable parameters for the preparation of OSA starch from early indica rice starch in aqueous slurry systems were as follows: concentration of starch slurry 35% (in proportion to water, w/w), reaction period 4 h, pH of reaction system 8.5, reaction temperature 35 degrees C, amount of OSA 3% (in proportion to starch, w/w). The degree of substitution (DS) was 0 018 and the reaction efficiency (RE) was 78%. FT-IR spectroscopy showed characteristic absorption of the ester carbonyl groups in the OSA starch at 1724 cm(-1). SEM and X-ray diffraction revealed that OSA groups acted by first attacking the surface and some pores formed, but OSA modification caused no change in the crystalline pattern of rice starch up to DS 0.046. RVA results indicated that the starch derivatives gelatinized at shorter time to achieve higher viscosities with increased OSA modification.