采用超声辅助酸性乙醇沉淀法制备高纯度白魔芋葡甘聚糖（Konjac Glucomannan, KGM），以白魔芋KGM纯度为评价指标，通过单因素和响应面优化制备高纯度白魔芋KGM的最佳工艺条件，并分析其理化性质和结构。结果表明，超声辅助酸性乙醇法制备KGM的最佳条件为：超声时间28 min、溶剂pH值为3.7、70%体积分数的乙醇、料液比1:75、超声温度为60 ℃，在此条件下进行的验证试验KGM纯度为97.08%，与常规超声辅助乙醇提取法相比有较大提高。与白魔芋原粉相比，KGM的持水力（51.39 g/g）、膨胀力（17.05 mL/g）、黏度（34 600 mPa•s）、阳离子交换能力和色度均得到提高，持油力（2.69 g/g）约为原粉的1.5倍。与95 wt.% KGM标品相比，以上理化性质无显著差异。微观结构显示，KGM表面杂质少，有大量类似蜂窝状的细小孔隙结构；傅里叶红外谱图显示KGM分子结构中具有多糖的特征吸收峰；热重分析表明，试验制备的样品纯度高，热稳定性好。此法制备的KGM具有较好的理化功能特性，研究结果可为高纯度魔芋葡甘聚糖的深入开发应用提供参考。

High-purity white konjac glucomannan (KGM) was prepared using the ultrasound-assisted acid-ethanol precipitation method. The purity of KGM was used as the evaluation index, and single-factor experiments and the response surface methodology were used to optimize the process conditions. Furthermore, the physicochemical properties and structure of KGM were analyzed. According to the results, the optimum conditions for the preparation of KGM using the ultrasoundassisted acid-ethanol precipitation method are as follows: ultrasonic treatment duration, 28 min; solvent pH, 3.7; volume fraction of ethanol, 70%; solid-to-liquid ratio, 1:75; and ultrasonic treatment temperature, 60 ℃. Under these conditions, the purity of KGM reached 97.08%, which is significantly higher than that of products obtained using conventional ultrasoundassisted ethanol extraction. Compared with raw white konjac powder, the high-purity KGM possessed improved water holding capacity (51.39 g/g), swelling power (17.05 mL/g), viscosity (34 600 mPa•s), cation-exchange capacity, and chroma. In particular, its oil holding capacity (2.69 g/g) was approximately 1.5 times that of raw white konjac powder. Compared with the 95% KGM standard, the experimentally obtained KGM exhibited no significant difference in the abovementioned physical and chemical properties. The microstructure analysis indicated that the surface of KGM had few impurities and a large number of small pore structures, similar to a honeycomb. Fourier-transform infrared spectroscopy revealed that the molecular structure of KGM had characteristic absorption peaks of polysaccharides. Thermogravimetric analysis indicated that the extracted sample was of high purity and had good thermal stability. Therefore, KGM prepared using the proposed method has good physical and chemical properties. These results provide a reference for the further development and application of high-purity KGM.

中央引导地方科技发展项目（2022ZYD0170）；四川省科技成果转移转化示范项目（2023ZHCG0080）；西华大学“大学生创新创业训练计划”项目（201710623017）