以甘薯渣为原料制备果胶,采用高效离子交换色谱测定果胶单糖构成,滴定法测定果胶酯化度(DE),并利用扫描电镜对果胶粉及果胶凝胶显微结构进行观察,进而探讨了温度、pH值、剪切速率、Ca2+浓度对果胶溶液黏度的影响。结果表明:果胶单糖含量高低顺序为半乳糖醛酸(79.23%)>半乳糖(9.48%)>鼠李糖(7.38%)>葡萄糖醛酸(3.76%)>木糖(3.74%)>葡萄糖(1.47%)>阿拉伯糖(1.23%),DE为31.71%。甘薯果胶粉呈不规则片状,而其凝胶则具有多孔网状结构。随着温度升高,果胶溶液黏度均呈下降趋势;pH值对黏度的影响较大,pH值5.0和9.0时,果胶溶液黏度最高,分别为3.82mP.s和3.65mP.s;随着剪切速率增大果胶溶液黏度迅速降低后趋于稳定;Ca2+能显著提高果胶溶液黏度,且在0～50 mmol/L内,Ca2+浓度与果胶溶液黏度值间存在一定正相关。

Pectin was extracted from sweet potato residues.Sugar composition and degree of esterification(DE) of pectin were determined by high performance anion exchange chromatography and titration method respectively.Mi-crostructure of pectin powder and pectin gel was observed by scanning electron microscope.The effect of temperature,pH,shear rate and Ca2 + concentration on viscosity of pectin solution were also investigated.The results showed that The order of sugar composition in sweet potato pectin was galacturonic acid(79.23%) > galactose(9.48%) > rham-nose(7.38%) > glucuronic acid(3.76%) > xylose(3.74%) > glucose(1.47%) > arabinose(1.23%),DE was 31.71%.The microstructure of pectin powder was irregular flake-like,whereas the pectin gel had a porous network form.The viscosity of pectin solution decreased when the temperature was increasing;pH affected viscosity obviously,pectin solution had higher viscosity at the pH 5.0 and 9.0,and the value were 3.82mP.s and 3.65mP.s respec-tively.With increasing the shear rate,viscosity decreased rapidly,and then trended to steady;Ca2 + could improve the viscosity of pectin solution remarkably,in the extent of 0 ～ 50 mmol/L,there was positive relationship between Ca2 + concentration and viscosity of pectin solution.