Functional characteristics of starches from the root of Cynanchum auriculatum Royle ex Wight grown in China

Starches isolated from two types of Cynanchum auriculatum Royle ex Wight roots grown in China (BW 201001 and HSW 6-18) were investigated and compared to commercial potato starch. The protein, lipid, ash and amylose content of BW 201001 and HSW 6-18 starches were 0.12%, 0.15%, 0.16%, 17.48%, and 0.15%, 0.13%, 0.11%, 21.10%, respectively. The starch granules were irregular with a round or polygonal shape and a size ranging between 5 and 15 μm. Compared to HSW 6-18 starch, BW 201001 starch had a higher solubility, water binding capacity, average chain length, and proportion of B1 chains, and a lower swelling power, syneresis, and proportion of A chains. Both starches showed the characteristic B type X-ray pattern. The degree of crystallinity and R(1047/1022) of BW 201001 and HSW 6-18 were 43.03%, 0.50, and 38.78%, 0.42, respectively. Gelatinisation temperatures followed the order of BW 201001 > HSW 6-18. The peak viscosity, setback, and final viscosity of BW 201001 were lower than those of HSW 6-18 starch. Both starches exhibited lower RDS and higher RS, which was related to their crystal and molecular structures.