κ-卡拉胶的高温高压法降解工艺和降解机制研究

Study on the degradation process and degradation mechanism of κ-carrageenan by high temperature and high pressure method

中文关键词:  κ-卡拉胶  高温高压  寡糖指纹谱图  降解机制

英文关键词:κ-carrageenan  high temperature and high pressure  oligosaccharide profile  degradation mechanism

中文摘要:

      目的 研究高温高压降解法降解κ-卡拉胶制备水溶性卡拉胶的工艺和降解产物的寡糖指纹谱图, 探究κ-卡拉胶的糖链结构特点和高温高压降解机制。方法 采用聚丙烯酰胺凝胶电泳法、高效分子排阻色谱分析高温高压降解产物的分子量和得率。采用傅里叶变换红外光谱法(Fourier transform infrared spectroscopy, FT-IR)分析κ-卡拉胶降解前后的结构变化。利用亲水液相色谱-高分辨质谱法(hydrophilic interaction liquid chromatography-high resolution mass spectrometry, HILIC-HRMS)比较不同pH时, 降解产物的寡糖指纹谱图。结果 采用乙酸溶液调节溶液的pH在4.0~5.0之间, 高分子量κ-卡拉胶在100~120℃加热30~90 min后迅速降解, 可以获得不同分子量的降解产物。pH和温度对卡拉胶的高温高压降解产物的分子量和得率有很大的影响, 高温高压降解不会改变卡拉胶原有的结构。降解产物的寡糖指纹谱图显示, 高温高压降解获得的卡拉胶寡糖产物主要是聚合度2~8的卡拉胶偶数糖和微量的奇数糖, 还有约20%的聚合度1~8的硫酸半乳寡糖。寡糖指纹谱图证明κ-卡拉胶的糖链主要是由4-硫酸半乳糖-3,6内醚半乳糖二糖单元组成, 还存在少量的无硫、双硫酸化、三硫酸化二糖单元, 以及不同硫酸化的半乳寡糖结构域。不同硫酸化寡糖产物的存在证明κ-卡拉胶的糖链中存在不同硫酸化的半乳糖-3,6内醚半乳糖二糖和半乳寡糖片段。结论 通过控制溶液的pH、降解温度和时间, 高温高压法可以快速、高效地制备降解卡拉胶, 高温高压降解和HILIC-HRMS可以准确地分析κ-卡拉胶糖链的精细结构, 对不同的寡糖域进行定性和定量分析。

英文摘要:

      Objective To study the degradation process of water-soluble carrageenan preparation from κ-carrageenan by high temperature and high pressure and oligosaccharide profile of the degradation products, and explore the characteristics of the sugar chain structures and the mechanism of high temperature and high pressure degradation of κ-carrageenan. Methods The molecular weights and recovery rates of the degradation products at high temperature and high pressure were analyzed by polyacrylamide gel electrophoresis and high performance gel exclusion chromatography. The structural changes of κ-carrageenan before and after degradation were analyzed by Fourier transform infrared spectroscopy (FT-IR). The oligosaccharide profile of degraded products in different pH were analyzed by hydrophilic interaction liquid chromatography-high resolution mass spectrometry (HILIC-HRMS). Results The κ-carrageenan at pH 4.0?5.0 adjusted by ethylic acid was effectively degraded to soluble κ-carrageenan with different molecular weight at 100?120℃ for 30?90 min. The pH and temperature had great influence on the molecular weights and recovery rates of degradation products of carrageenan by high temperature and high pressure, high temperature and high pressure did not change the original structure of carrageenan. The oligosaccharide profile of degraded carrageenan demonstrated that the carrageenan oligosaccharides obtained by high temperature and high pressure degradation were mainly even-numbered oligosaccharide with polymerization degree of 2?8 and trace odd-numbered oligosaccharide, as well as about 20% sulfated galacto-oligosaccharides with polymerization degree of 1?8. The oligosaccharide profile proved that carrageenan was composed of 4-sulfated galactan-3,6-anhydrate galactose disaccharide unit, as well as a small amount of sulfur-free, disulfated and trisulfated disaccharide unit, and galactan oligosaccharides with different sulfate groups. Existence of different sulfated oligosaccharide products of κ-carrageenan proved the existence of different sulfated galactan-3,6-anhydrate galactose disaccharide unit and galacto-oligosaccharides in the saccharide chain κ- carrageenan. Conclusion By control of pH and temperature, high temperature and high pressure method can quickly and efficiently the degraded carrageenan, the high temperature and high pressure and HILIC-HRMS can accurately analyze the structure of κ-carrageenan, and analyze different oligosaccharide domains qualitatively and quantitatively.