Physicochemical and Functional Properties of Starches from Pachyrhizus erosus with Low Digestibility

The search for novel natural ingredients has been stimulated by the food and non-food industries, and roots of Pachyrhizus erosus (jicama) emerges as promising crops for industrial production due to its crispy and succulent flesh and high yield. Therefore, jicama starches from Fujian Province (SFJ) and Guangxi Province (SGX) were isolated and the microstructure, swelling power, crystallinity, thermal property, rheological property, and in vitro digestibility were determined. The starch granules of SFJ and SGX showed polyhedral, spherical or semi-spherical shapes with smooth nonporous surface. SFJ and SGX showed increasing solubility and swelling power with the increasing of temperature. By X-ray diffraction analysis, both had typical A-type crystallinity, but SFJ showed lower relative crystallinity (29.4%) than SGX (35.4%). SFJ with smaller granule sizes and lower relative crystallinity showed weaker thermal stability, lower viscosity, weaker strength of starch gels, and lower Resistant Starch (RS) content. The high contents of RS in SFJ (65.67%) and SGX (70.37%) suggested that jicama is promising low energy food for special purposes.