Vodenicarová M, Drímalová G, Hromádková Z, Malovíková A, Ebringerová A
CPN spol.s r.o., 561 02 Dolní Dobrouc, Czech Republic.
Ultrason Sonochem. 2006 Feb;13(2):157-64. doi: 10.1016/j.ultsonch.2005.03.001. Epub 2005 Jun 1.
Tamarind seed xyloglucan was subjected to different radiation sources-ultrasound, gamma-radiation, and microwave heating, and the effects of these energies upon its molecular and structural properties were characterised by gel permeation chromatography, viscometry, sugar analysis, FT-IR and NMR spectroscopic techniques. In dependence on the degradation methods and experimental conditions used, the decrease of the relative molecular mass (RMM) was accompanied with alteration of the primary structure. Depolymerisation by ultrasound at a frequency of 20 kHz yielded after 120 min products with RMM of about 131 x 10(3) without significant alteration of the primary structure of the polysaccharide. Intense degradation of XG started by microwave heating at pH 1.5 yielding polymers with RMM in the range of higher oligosaccharides, however, with changed sugar composition due to cleavage of the glycosyl side chains. At gamma-irradiation doses >40 kGy, next to chain cleavage, very high-molecular mass components exhibiting UV(254)-absorption were formed, and the RMM decreased to about 50 x 10(3) at the highest applied dose (100 kGy). The results of the comparative study suggest that ultrasonication was the most convenient procedure to decrease the RMM of xyloglucan to 130 x 10(3) and preserve the primary structure of the polysaccharide.
罗望子种子木葡聚糖受到不同辐射源——超声、γ辐射和微波加热的作用，通过凝胶渗透色谱法、粘度测定法、糖分析、傅里叶变换红外光谱和核磁共振光谱技术对这些能量对其分子和结构性质的影响进行了表征。根据所使用的降解方法和实验条件，相对分子质量（RMM）的降低伴随着一级结构的改变。在20 kHz频率下通过超声解聚120分钟后，得到的产物RMM约为131×10³，而多糖的一级结构没有明显改变。在pH 1.5条件下通过微波加热开始对木葡聚糖进行强烈降解，得到的聚合物RMM处于较高寡糖范围内，然而，由于糖基侧链的裂解，糖组成发生了变化。在γ辐射剂量>40 kGy时，除了链断裂外，还形成了具有紫外（254）吸收的非常高分子质量的组分，并且在最高施加剂量（100 kGy）下RMM降至约50×10³。比较研究结果表明，超声处理是将木葡聚糖的RMM降低至130×10³并保留多糖一级结构的最便捷方法。
