Characterization of new starches separated from different Chinese yam (Dioscorea opposita Thunb.) cultivars

The starches separated from four different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal, crystal, and physicochemical properties, such as amylose content, swelling power, solubility and water-binding capacity properties. Amylose content of D. oppositastarches from different cultivars ranged from 20.74% to 25.94%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or elliptic. The mean particle diameter of starches ranged from 23.39 to 26.87 mu m. The transition temperatures (T-o, T-p and T-c) and enthalpy of gelatinization (Delta H-gel) were determined using differential scanning calorimetry (DSC). T-o, T-p and T-c varied from 73.6 to 74.8, 78.8 to 81.0, and 83.3 to 87.2 degrees C, respectively. D. opposita cv. Jinchengerhao starch showed the highest Delta H-gel values (12.48 J/g) while D. opposita cv. Baiyu starch showed the lowest values (9.413 J/g). The crystal type of starches separated from different D. opposita cultivars was a typical C-H-type pattern. The degrees of crystallinity of the four D. opposita cultivars starches were about 50.52%, 32.99%, 33.57%, and 36.16%, respectively. (c) 2005 Elsevier Ltd. All rights reserved.