Isolation of starch from acha grain (Digitaria exilis (Kippist) Stapf), modification, characterization and application of benzoylated starch in stabilization of oil in water emulsion

Abstract

Starch and its derivatives are biocompatible, biodegradable, non-toxic with applications in food, pharmaceutical and allied industries. In this study, starch was isolated from acha grain (Digitaria exilis (Kippist) Stapf). Esterification of starch was carried out using benzoyl chloride at room temperature (30 °C ± 2 °C). Characterization of native and benzoylated starch were achieved by FT-IR and XRD analyses. Emulsifying properties of native and benzoylated starch were reported. FT-IR spectra of native modified revealed the broad absorption bands at 3375.70 cm-1 was due to stretching hydrogen bonded O-H groups in the starch. However, for the modified starch, the major new absorption bands at 1600.92 cm-1 which is associated with C=O esters indicating the modification of the native starch confirms that esterification took place in the starch molecules and the band in the region 1716.65 cm-1 confirms the water adsorption. The X-Ray diffraction pattern of native and acetylated starch samples prominent peaks (2) at 18.08 and 19.02 respectively. After acetylation, slightly reduction in crystallinity was observed. The loss of crystallinity would mean enhanced ability for acetylation starch or other polymer products made from it to absorb water. The native and benzylated starch significantly enhanced the stability of water of oil water emulsion.