| The resource of chestnut is affluence in Chinese, as traditional agricultural and sideline product, it’s processing and utilization rate is relatively low. In order to expend the processing and utilization of Chinese chestnut, this present research aims to prepare chestnut starch under various conditions. Chestnut starch was taken as the experimental material. Heat-moisture treatment (HMT) was used for physical modification on chestnut starch under various conditions, including various time(2～18 h), temperature(80～120℃)and humidity(10%～30%). As the time of heat-moisture treatment increases, the degree of solubility and swell capacity of chestnut starch decreased and was significantly influenced by temperature. On the other side, HMT led to the decline of its transparency.SEM revealed that native chestnut starch granules with no obvious effects or signs of damage on the surface was round, elliptical and polygonal in shape with smooth surfaces. However, the granular structure of modification was destroyed after being heat-moisture treated, and resulted in a loss of granular appearance and thus an irregular shape. X-ray diffraction analysis indicated that modified starch has a C crystallization type, same as the original one. However, there appeared new structure in modified granular. Infrared spectroscopy analysis showed that the chestnut starch treated by HMT bore little difference with original chestnut starch with regard to the position, intensity and shape of its main characteristic peaks in infrared spectrogram. The modified chestnut starch did not form new peaks, indicating there was no change on the primary structure of starch. The increase in the some adsorption peaks showed that the HMT changed internal arrangement of the secondary structure of starch. The change of the ratio of two adsorption peaks, one representing ordered crystalline and other non-crystalline, indicated an increase of ordered crystalline structure inside the starch granules.The degree of swelling, solubility and transparency of chestnut starch after HMT are all lower than the original one. The modified chestnut starch demonstrated a stronger coagulation and precipitation tendency and, even under various preparation conditions, its drainage rate after freezing and thawing are higher than the original chestnut starch. But after multiple freezing and thawing the modified chestnut starch showed a stronger stability. Scanning calorimetry analysis showed that after HMT the initial gelatinization temperature, endothermic peak and final gelatinization temperature of modified chestnut starch all rose, and gelatinization enthalpy increased. |
PDF Full Text Request