本研究采用草酸对柠檬皮进行分步提取，得到两种不同性能的高酯果胶(HMP-1、HMP-2)，系统地探究了提取条件HMP-1和HMP-2得率和黏度的影响，对HMP-1、HMP-2进行物化性质表征，并通过原子力显微镜(AFM)进行微观结构观察。实验结果表明，在料液比1:20，pH 1.7，70 ℃ 1.5 h的反应条件下，HMP-1得率为19.22%，1%溶液的黏度为104.55 mPa·s，分子量为550.4 ku，酯化度为75.22%，胶凝度为218.24 °SAG，在酪蛋白等电点附近具有较高的电位绝对值；在料液比1:10，pH 1.7，80 ℃1.5 h的反应条件下，HMP-2的得率为9.74%，1%溶液的黏度为49.23 mPa·s，分子量为424.7 ku，酯化度为64.34%，胶凝度为171.12 °SAG。AFM结果表明，HMP-1呈现较长的线性形态，HMP-2则呈现较为分散、细碎的状态。本研究实现了柠檬皮果胶的分步提取，得到不同类型的果胶，有助于果胶的多元化发展及精准应用。

In this study, two high methoxyl pectins (HMP-1 and HMP-2) with different properties were extracted from lemon peel with organic acid using a stepwise method. The effects of extraction conditions on the yield and viscosity of HMP-1 and HMP-2 were systematically studied. The physicochemical properties of HMP-1 and HMP-2 were investigated, and the microstructure was examined by atomic force microscopy (AFM). Under the conditions of material to liquid ratio 1:20, pH 1.7, 70 ℃ and 1.5 h, the yield of HMP-1 was 19.22%, viscosity of 1% HMP-1 solution was 104.5 mPa·s, molecular weight of HMP-1 was 550.4 ku, degree of esterification (DE) of HMP-1 was 75.2%, and HMP-1 gel strength was 218.24 °SAG, with the absolute value of solution potential being relatively high near the isoelectric point of casein. In terms of HMP-2, under the conditions of material to liquid ratio 1:10, pH 1.7, 80 ℃ and 1.5 h, the yield was 9.74%, viscosity of 1% solution was 49.3 mPa·s, molecular weight was 424.7 ku, degree of esterification was 64.3%, and gel strength was 171.12 °SAG . The exainations with AFM showed that HMP-1 exhibited a relatively long linear shape, whilst HMP-2 was relatively dispersed and finely fragmented. In this study, the stepwise extraction of pectins was realized to obtain different types of pectins, which helps the diversification and precise application of pectins.

国家自然科学基金项目（31370036）