Structure Identification of Germplasm Resources of Lotus with High Resistant Starch

This study focused on resistant starch (RS) from lotus, analyzing its content and structural characteristics across different lotus germplasms. Detection using the Dual-Wavelength Colorimetric Method revealed the following findings: The proportion of amylose in fresh lotus rhizomes was higher than that in fresh lotus seeds. The average content of resistant starch in fresh lotus rhizomes was also higher than that in fresh lotus seeds. After cooking, the resistant starch content of both lotus rhizomes and seeds decreased, with lotus seeds retaining a relatively higher amount of resistant starch post-cooking. Structural characterization showed that the surface of resistant starch from lotus seeds exhibited a grooved morphology, whereas that from lotus rhizomes appeared as irregular clusters. Additionally, the structure of raw resistant starch was more compact than that of cooked resistant starch. Fourier Transform Infrared (FTIR) Spectroscopy and X-ray diffraction (XRD) analyses confirmed that all lotus-derived resistant starches formed a type-C crystalline structure, with the crystallinity of resistant starch from lotus seeds being higher than that from lotus rhizomes. This study provides a theoretical foundation for breeding of high-RS lotus varieties and for the effective utilization of lotus germplasm. This work systematically compares RS composition and multi-scale structural differences between two edible lotus organs across a large germplasm population, clarifying the structural basis of RS variation, which distinguishes this study from previous single-material lotus RS research.