The effect of octenylsuccinylation on morphological, rheological, and in vitro digestibility properties of Canna edulis Ker starch

Abstract

Canna edulis Ker (canna) starch was modified in aqueous slurry systems with octenyl succinic anhydride (OSA) and the effect of four major reaction parameters (concentration of starch slurry (%), reaction time (h), reaction temperature (°C), and pH) on the degree of substitution (DS) were evaluated by both single-factor and response surface methodology (RSM) methods. Octenylsuccinylation-induced changes in morphological, rheological, and in vitro digestibility properties were also examined. The RSM results indicated that the optimal conditions for the preparation of OSA canna starch (DS-‰=-‰0.0121) was 35% (w/v) starch concentration at pH 8.0, reacted at 35°C for 3.5-‰h, and the highest RS content obtained was 52.2%. Light microscopy revealed that octenylsuccinylation did not cause remarkable morphological changes as indicated by clear birefringence under polarized light. In conclusion, though octenylsuccinylation was a surface esterification, OSA-modification increased the viscosity of canna starch dramatically. However, increased DS did not further improve the viscosity of OSA canna starch, possibly due to high amounts of RS.