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 (R-z), even though the weight-average molar weight (M-w) and molecular density (rho) were reduced. Two newabsorption bands (1725 and 1570 cm(-1)) were observed for OS-starch. The heat of gelatinization (Delta H), onset (T-o), peak (T-p), and conclusion (T-c) temperatures decreased as the OSA level increased. OSA level did not significantly affect relative crystallinity (X-c), 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. (C) 2016 Elsevier B.V. All rights reserved.