Abstract:

Octenyl succinate anhydride (OSA)-modified potato starch was synthesized by base-catalyzed reaction of octenyl succinate anhydride with granular starch in aqueous suspension using Tween-20 as dispersing agent. An orthogonal array design involving 4 factors (starch concentration, OSA concentration, reaction temperature, pH value) at 3 levels was employed to optimize the reaction conditions. The structure of OSA potato starch was characterized with fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Optimum degree of substitution (DS) was obtained when the reaction was performed between 40% potato starch slurry and 5% OSA at 30 ℃, pH 7.5－8.0. FT-IR spectrum of OSA starch showed the intensified absorption peaks at 1651 cm-1 and 573 cm-1, and characteristic absorption peaks of RCOO－ at 1558 cm-1 and ＞C=O at 1730 cm-1, which suggest the formation of ester. SEM image showed that OSA potato starch granular had rougher surface than native potato starch, and thus had higher specific surface area.

Key words: potato starch, octenyl succinate anhydride, degree of substitution, esterification reaction