山楂生、炒品果胶结构表征和体外降脂作用研究

Structural characterization and in vitro lipid-lowering effect of pectin from raw and fried hawthorn

中文关键词:  山楂  生品果胶  炒品果胶；结构表征  体外降脂

英文关键词:hawthorn  raw hawthorn pectin  fried hawthorn pectin  structural characterization  in vitro lipid-lowering

中文摘要:

      目的 明确山楂生品果胶(raw hawthorn pectin, RHP)和炒品果胶(fried hawthorn pectin, FHP)的结构与其体外降脂作用的关系。方法 通过测定酯化度、半乳糖醛酸含量、分子量、特性黏度、黏均分子量、中性糖组成和比例, 用扫描电镜观察微观形态, 来表征RHP和FHP的结构。通过果胶对胆固醇胶束和胆酸盐的结合能力等体外实验评价其降脂作用。结果 RHP酯化度为52.19%, 属于高酯果胶; FHP酯化度为31.95%, 属于低酯果胶。RHP分子量有4个级分 (217904、16907、8933、5104 Da), FHP分子量有4个级分 (238813、16662、8770、5063 Da)。RHP特性黏度和黏均分子量分别为0.10 dL/g和2.75×104 g/moL, FHP特性黏度和黏均分子量分别为0.16 dL/g和4.71×104 g/moL。RHP、FHP均含有葡萄糖、鼠李糖、半乳糖、果糖和木糖等中性糖, 但各糖的分子摩尔比不同。微观形态中, RHP分子间交联良好; FHP分子之间交联较少。在体外降脂实验中, RHP对胆固醇胶束和胆酸盐结合能力强于FHP。结论 山楂炒制后, 果胶的特性黏度和黏均分子量升高, 分子量分布无明显变化, 部分级分分子量降低, 果胶的交联程度、半乳糖醛酸含量、酯化度降低，体外降脂作用降低。炒制使果胶结构发生了改变从而影响其降脂作用。

英文摘要:

      Objective To clarify the relation between the structure and lipid-lowering effect of raw hawthorn pectin (RHP) and fried hawthorn pectin (FHP). Methods The structural characteristics of RHP and FHP were characterized by determining the degree of esterification, the content of galacturonic acid, molecular weight, intrinsic viscosity, viscosity average molar weight, composition and proportion of neutral sugar, together with observing the microscopic morphology with scanning electron microscope. The binding abilities of RHP and FHP to cholesterol micelles and cholate were evaluated by experiments in vitro. Results The esterification degree of RHP was 52.19%, and that of FHP was 31.95%, belonging to high-ester and low-ester pectin, respectively. RHP had 4 molecular fractions (217904, 16907, 8933, 5104 Da), and FHP also had 4 molecular fractions (238813, 16662, 8770, 5063 Da). The intrinsic viscosity and viscous average molecular weight of RHP were 0.10 dL/g and 2.75×104 g/moL, respectively, and those of FHP were 0.16 dL/g and 4.71×104 g/moL, respectively. RHP and FHP contained neutral sugars, mainly glucose, rhamnose, galactose, fructose, and xylose, with different molar ratio. Micromorphological observation showed that there were cross-links between RHP molecules which were less than those in FHP. RHP had a stronger binding ability to cholesterol micelles and cholate than FHP in vitro. Conclusion After fried, the intrinsic viscosity and viscosity average molecular weight increase with unobvious change in the distribution of molecular weight, but some molecular of hawthorn pectin degrade. The cross linking, content of galacturonic acid, esterification degree, and in vitro lipid lowering effect of the pectin reduce after fried. The structure of the pectin changes in fried hawthorn, which affects its lipid-lowering effect.