New starches from traditional Chinese medicine (TCM)—Chinese yam (Dioscorea opposita Thunb.) cultivars

The starches separated from two different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal and crystal properties. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or irregular. The surface of the starch granules appeared to be smooth without any fissures. The average particle diameter of starches from different D. opposita Thunb. cultivars was 40.3 and 38.7 μm for D. 47 and D. SXY starch, respectively. The transition temperatures (To, Tp and Tc) and enthalpy of gelatinization (ΔHgel) were determined using differential scanning calorimetry (DSC). The D. SXY starch showed the lower To (74.2 °C) and the broader R (12.4). Tp and Tc of starch from D. 47 were higher than that of D. SXY starch. ΔHgel values (11.37 J/g) of D. 47 was higher than that of D. SXY starch (10.78 J/g). The crystal type of starches separated from two different D. opposita cultivars was a typical C-type pattern. The degree of crystallinity of two D. opposita cultivars starches was about 45.9% and 31.5%, respectively.