Changes in structure and properties of starch of four botanical sources dispersed in the ionic liquid, 1-butyl-3-methylimidazolium chloride

Ionic liquid (IL) has gained industry attention, especially in green chemistry. Researchers have utilized IL for dispersing cellulose, but no report using IL for other polysaccharides. In this study, corn, rice, wheat and potato starches were dispersed in hot water (DIHW) or IL, 1-butyl-3-methylimidazolium chloride and morphology, amylopectin molecular weight (APMw) and thermal properties (TP) were analyzed. For starch DIHW, corn and potato had gelatinized aggregates, whereas rice and wheat had granular clumps. Starch heat-dispersed in IL (HDIIL) had clumps composed of < 1 μm diameter particles. Starch DIHW had little effect on APMw. Cereal starches had APMw greatly reduced by HDIIL (4-6 peaks observed). Potato amylopectin was degraded less by IL (two peaks) probably because charged phosphomonoesters covalently bonded to imidazolium rings or repelled IL chloride ions and large granule size impeded IL penetration, reducing reaction efficiency. TP showed potato starch incompletely gelatinized by HDIIL.