Physicochemical and structural characteristics of the octenyl succinic ester of ginkgo starch.

The physicochemical and structural characteristics of octenyl succinate (OS)-starch prepared from ginkgo starch were investigated. The degree of substitution (DS) and reaction efficiency of 1.5 and 3.0% OSA-modified starch were 0.0065, 77.9% and 0.0172, 70.4%, respectively. OSA modification caused a reduction in glucose yield but no significant changes in the z-root mean square radius of gyration (Rz), even though the weight-average molar weight (Mw) and molecular density (ρ) were reduced. Two newabsorption bands (1725 and 1570cm(-1)) were observed for OS-starch. The heat of gelatinization (ΔH), onset (To), peak (Tp), and conclusion (Tc) temperatures decreased as the OSA level increased. OSA level did not significantly affect relative crystallinity (Xc), showing that OSA esterification occurred primarily in the amorphous domain. The rheological characteristics of OS-starch pastes indicated highly shear-thinning fluids. This study showed that changes in digestibility and rheological properties of OS-starch depended both on DS and starch structure.