Polyethylene glycol (PEG) was further applied for fractionating dextrin prepared from cassava starch. The initial dextrin concentration and pH of the dextrin solutions were crucially considered in this study with the average molecular-weight dispersity (D_Ma) as the index. The results showed that the initial dextrin concentration significantly affected the mass fraction and the molecular weight distribution of each dextrin fraction obtained from gradient PEG precipitation. However, the initial dextrin concentration, which ranged from 0.9% to 3.6%, did not affect the D_Ma of the dextrin fractions. Furthermore, the D_Ma of the fractions obtained at pHs 4.00, 4.96, 6.00, 6.92, 7.99, 8.96, and 9.91, was 1.364, 1.341, 1.305, 1.286, 1.273, 1.311, and 1.404, respectively, while the dispersity of the parent dextrin was 2.052. These results suggest that the preparative approach, gradient PEG precipitation, is applicable in acidic, neutral, and alkaline environments, and that a weakly alkaline environment is optimal for dextrin fractionation.

进一步将聚乙二醇（PEG）应用于分馏由木薯淀粉制得的糊精。在本研究中，以平均分子量分散度（D _Ma）为指标，着重考虑了糊精溶液的初始糊精浓度和pH值。结果表明，初始糊精浓度显着影响了从梯度PEG沉淀获得的每个糊精组分的质量分数和分子量分布。但是，初始糊精浓度在0.9％至3.6％的范围内，不会影响糊精级分的D _Ma。此外，D _Ma在pH 4.00、4.96、6.00、6.92、7.99、8.96和9.91下获得的馏分分别为1.364、1.341、1.305、1.286、1.273、1.311和1.404，而母体糊精的分散度为2.052。这些结果表明，制备方法，梯度PEG沉淀法，适用于酸性，中性和碱性环境，弱碱性环境是糊精分离的最佳选择。