Structural, physicochemical and rheological properties of a novel native starch obtained from Rhizoma Gastrodiae

Rhizoma Gastrodiae (RG) is traditional medicine and food, widely used in many Asian countries. Extracting starch from RG is a supplementary for the exploitation of new starch sources. The present work aimed to characterize the extracted starch from RG residues concerning its composition, physicochemical, structural and rheological characteristics. The isolated RG starch had notably high amylopectin (AP) content of 92.75 % with a purity of 94.9 %. The RG starch displayed a characteristic of B-type and had a crystallinity of 45.60 %. Color analysis of RG starch indicated its acceptable color characteristics. Particle size and morphology analysis revealed its small size (0.62-1.48 mu m). Compared to maize, sweet potato and peas starches, the RG starch exhibited higher swelling power, solubility, digestibility, and lower pasting temperature. The lower setback viscosity and final viscosity suggested its better anti-aging capability. Besides, static rheological measurements of RG starch pastes presented a pseudo-plastic behavior under the measured shear rates (1-500 s(-1)); dynamic rheological measurements showed that RG starch gels were typical weak gel system and had better long-term stability in a lower concentration. With small granule size, high AP content and low gelatinization temperature, the RG starch showed the unique potential in the food industry.