Morphology, X-ray Diffraction and Solubility of Underutilized Legume Starch Nanocrystals

Nanocrystals of the native starches isolated from lima bean (Phaseolus lunatus) and jack bean (Canavalia ensiformis) were prepared by mild acid hydrolysis. The shapes and granular sizes of the native starches were obtained by a scanning electron microscope. Platelets that existed as aggregates rather than discrete molecules were observed from the transmission electron micrographs of the nanocrystals. The X–ray diffraction of the starch nanocrystals showed that they were of V–type crystalline structure. Lima bean nanocrystals were sparingly soluble in acetic acid, ethanol and deionized (DI) water. These starch nanocrystals could be potential precursors to nanocomposites and nanoparticle-based copolymers.