乙醇沉淀法是纯化果胶的工业化方法，应用广泛。本文以甜菜果胶为研究对象，考察了醇析pH、乙醇浓度等对甜菜果胶的醇析率、物化特性的影响；通过zeta电位表征甜菜果胶在醇析过程中的分子相互作用，并采用通过高效液相体积排阻色谱（HPSEC）、高效阴离子色谱（HPAEC）和高效液相色谱（HPLC）等技术分析醇析所得甜菜果胶的分子结构。研究结果表明：纯化前后的SBP醇析率均在pH为2.5，体系乙醇浓度为71.25%时达到最大，分别为96.81%和57.23%；SBP的重均分子量范围为145.07~404.27 kg/mol；含有鼠李糖、阿拉伯糖、半乳糖、葡萄糖和木糖等五种中性糖，范围为16.23~17.83%。SBP溶液初始pH与体系乙醇浓度在一定范围内对SBP的水合作用有影响，醇沉所得SBP的结构受到了醇析条件的影响。

Ethanol precipitation is widely used for purifying pectin in industrial production. The effects of precipitation pH and ethanol concentration on the ethanol precipitation yield and the physicochemical characteristics of sugar beet pectin (SBP) were studied. Zeta potential was used to characterize the interaction between SBP molecules during the precipitation process. The structure of SBP was analyzed by a series of techniques such as high-performance size exclusion chromatography (HPSEC), high-performance anion exchange chromatography (HPAEC), and high-performance liquid chromatography (HPLC). The results indicated that the highest precipitation rates of unpurified and purified SBPs were reached when the pH was 2.5 and the ethanol concentration in the system was 71.25%, with precipitation rates of 96.81% and 57.23%, respectively. The weight-average molar mass (Mw) of SBP ranged from 145.07 kg/mol to 404.27 kg/mol. Five neutral sugars, including rhamnose, arabinose, galactose, glucose, and xylose, were detected in SBP, and their content ranged from 16.23~17.83%. The I-pH and system ethanol concentration of SBP solution had impacts on SBP hydration to some extent, and the structures of precipitated SBP were affected by the ethanol precipitation conditions.

国家自然科学基金项目（31601423）；广东省科技计划项目（2013B051000015）；中国博士后科学基金项目（2016M590789）；广州市科技计划项目（201701060280）