Starch acetate with high DS was prepared by glacial acetic acid and acetic anhydride using methyl sulfonic acid as a catalyst. The influences of reaction temperature, reaction time, ratios of reactants on the esterifi...Starch acetate with high DS was prepared by glacial acetic acid and acetic anhydride using methyl sulfonic acid as a catalyst. The influences of reaction temperature, reaction time, ratios of reactants on the esterification have been examined. The product is characterized by chemical analysis, infrared analysis, intrinsic viscosity and solubility measurements. High linear amylose was found easier to be esterized.展开更多
This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different d...This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm?1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at temperatures from 328°C to 372°C, while the native starch underwent 50% weight loss at 325°C. The glass transition temperature (T g) of the starch decreased from 273°C to 226°c. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch decreased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) suggested that the most of the starch granules disintegrated with many visible fragments with the increasing DS.展开更多
文摘Starch acetate with high DS was prepared by glacial acetic acid and acetic anhydride using methyl sulfonic acid as a catalyst. The influences of reaction temperature, reaction time, ratios of reactants on the esterification have been examined. The product is characterized by chemical analysis, infrared analysis, intrinsic viscosity and solubility measurements. High linear amylose was found easier to be esterized.
基金the funds for New Century Elite of Education Ministry (Grant No. E105001)the funds from the Tianjin Municipal Science and Technology Commis-sion (Grant No. 07JCZDJC05400)Natural Science Foundation of Tianjin Mu-nicipal (Grant No. 08JCZDJC15300)
文摘This study was carried out to understand and establish the changes in physicochemical properties of starch extracted from Chinese yam (Dioscorea opposita Thunb.) after acetylation. Yam starch acetates with different degrees of substitution (DS) were prepared by the reaction of yam starch with glacial acetic acid/acetic anhydride using sulfuric acid as the catalyst. Their formation was confirmed by the presence of the carbonyl signal around 1750 cm?1 in the Fourier transform infrared (FT-IR) spectra. The thermal behavior of the native starch and starch acetate were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the starch acetates are more thermally stable than the native starch. The starch esters showed 50% weight loss at temperatures from 328°C to 372°C, while the native starch underwent 50% weight loss at 325°C. The glass transition temperature (T g) of the starch decreased from 273°C to 226°c. The X-ray diffraction (XRD) patterns could be classified as typical of the C-type for yam starch. X-ray diffraction also showed the loss of the ordered C-type starch crystalline structure and the degree of crystallinity of starch decreased from 36.10% to 10.96% with the increasing DS. The scanning electron microscopy (SEM) suggested that the most of the starch granules disintegrated with many visible fragments with the increasing DS.
