Comparative Evaluation of Structural Characteristics of Starch from 10 Varieties of Lotus Root

Starch extracted from ten lotus root varieties (Yeyong, MRHZ, Zhonghua, Suiningbaiou, Zaohua, Meirenhong, E9:11, Huchengyeou, Peixianyeou, Xin No. 5) from Jiangsu Province, China, were studied. The structural characteristics of lotus root starch were analyzed based on its physical and chemical properties, particle structure, crystal structure, layered structure, thermal properties and gel properties. The lotus root starches were generally milky white, with a starch content ranging from 81.72 to 99.54%, amylose content ranging from 15.44 to 23.54%, light transmittance between 15.30 and 26.90%, and swelling power and solubility at 22.15–29.72% and 2.00–6.00%, respectively. Among the varieties, “Suiningbaiou” had the whitest starch, while “Meirenhong” and “Suiningbaiou” had higher starch contents. “Huchengyeou” had the lowest amylose content, and “Zhonghua” showed the highest light transmittance. “Yeyong” and “Zaohua” had higher solubility, whereas “Zhonghua” had the highest swelling power. An optical, polarizing and scanning electron microscope revealed that most of the lotus starch was oval. However, starch from “Zhonghua”, “E9:11”, “Peixianyeou” and “Zaohua” was longer, whereas starch from “Meirenhong”, “MRHZ”, “Huchengyeou”, “Yeyong”, “Suiningbaiou” and “Xin No.5” was shorter. The X-ray powder diffraction patterns and 13C NMR spectroscopy indicated that “Zaohua” starch exhibited type A crystallization, while starch from the other varieties displayed type CA crystallization, with a relative crystallinity between 18.27 and 22.10%; “Huchengyeou” and “Yeyong” had higher crystallinity. Infrared spectroscopy and small-angle X diffraction analysis showed similar results for short-range order and lamella spacing. The thermal and gel properties of starch from the ten lotus root varieties also varied. The enthalpy change values of “Xin No.5” and “Yeyong” were higher, and starch from “Yeyong” and “Huchengyeou” showed a greater gel strength. Finally, factor score analysis ranked the starch quality of the top four lotus root varieties in Jiangsu as “Suiningbaiou”, “Yeyong”, “Huchengyeou”, and “Zaohua”.