Physicochemical properties of a new starch from ramie (Boehmeria nivea) root

A new starch was isolated from ramie root, and its physicochemical properties were investigated. Ramie dry root contained 45.9% starch. Starch had truncated, ellipsoidal, and spherical granule shapes with size from 7 to 30 μm and D[4,3] about 14.1 μm. Starch contained 38.9% apparent amylose content and 22.4% true amylose content, exhibited B-type crystallinity, and had 26.6% relative crystallinity, 0.82 ordered degree, and 9.2 nm lamellar thickness. Starch had 71.8 °C gelatinization peak temperature and 15.6 J/g gelatinization enthalpy, and exhibited 31.4 g/g swelling power and 17.1% water solubility at 95 °C. Starch had peak, hot, breakdown, final, and setback viscosities at 3048, 2768, 279, 4165, and 1397 mPa s, respectively, and showed peak time at 4.36 min and pasting temperature at 75.0 °C. The native, gelatinized, and retrograded starches contained 15.1%, 94.0%, and 86.5% rapidly digestible starch and 83.3%, 4.0%, and 10.7% resistant starch, respectively. Compared with potato and rice starches, ramie starch was somewhat similar to potato starch but significantly different from rice starch in starch component, crystalline structure, and functional properties. Therefore, ramie starch exhibited the potential to be used as a thickening agent, resistant-digesting food additive, and alternative to potato starch in food and nonfood industries. •The dry root of ramie contained 45.9% starch with granule size from 7 to 30 μm.•Ramie starch had truncated, ellipsoidal, and spherical granules and 22.4% amylose.•Ramie B-type starch had 26.6% relative crystallinity and 9.2 nm lamellar thickness.•Ramie starch had higher resistance to gelatinization and digestion than rice starch.•Ramie and potato starches were similar in some structural and functional properties.