Evaluation of three traditional Chinese medicine (TCM) starches and potential application in health product industry

Structural and functional properties of starches isolated from Ginkgo biloba L. (GBL), Angelica dahurica (Fisch. ex Hoffm.) Benth. et Hook. f. (ADB) and Bletilla sfriata (Thunb.) Reiehb. f. (BSR) have been studied using a range of characterization methods including amylose content, water-binding capacity, paste clarity, scanning electron microscopy (SEM) and light microscopy, X-ray diffraction (XRD), amylose leaching, differential scanning calorimetry (DSC) and in vitro digestion. Considerable differences in these properties were observed. Amylose content varied from 16.7% to 30.5%, while paste clarity was in the range of 8.03–25.3%. Moreover, the shape of starch granules varied from spherical, elliptical to irregular or polygonal with different sizes. ADB displayed a B-type pattern, while GBL and BSR showed a C-type pattern. In addition, amylose leaching (AML) varied linearly with temperature for BSR, while the AML of other samples increased gradually below 60 °C, but increased dramatically beyond 60 °C. The three starch samples had similar gelatinization temperature ranging from 63.0 to 76.7 °C, but showed lower enthalpy values (0.90–3.96 J/g) than most of conventional starch. GBL and ADB possessed much higher slowly digested starch (SDS) content in vitro digestion, which made them suitable candidates for dietary starch.