交联处理对甜菜果胶结构及流变性质的影响

Effects of Crosslinking Treatment on the Structure and Rheological Propertiesof Sugar Beet Pectin

采用漆酶制备不同交联时间的甜菜果胶(SBP),对其结构与流变性质进行研究。结果表明:随着交联时间的延长,SBP的摩尔质量呈先增加后减小的趋势。扫描电子显微镜(SEM)观察发现SBP块状结构在交联处理后变得逐渐蓬松,表面出现明显的细纹和蜂窝状结构。热重分析结果表明:SBP经交联处理后热稳定性增强,质量残留率从32.37%增到42.20%。X-射线衍射分析(XRD)表明:交联处理后SBP晶体结构未发生显著变化。流变学结果表明:SBP溶液属于假塑性流体,蔗糖质量浓度对SBP黏度随着剪切速率的变化影响显著。此外,在整个剪切速率范围,温度越高SBP的黏度越低。随着交联时间的延长,SBP的表观活化能Ea从1.659×10~4J/mol降到1.097×10~4J/mol,表明交联SBP的黏度受温度的影响减弱。研究结果为SBP的进一步开发利用提供一定的理论参考。

In this study,sugar beet pectin(SBP)with different crosslinking time was prepared by laccase,and its structure and rheological properties were studied.The results showed that the molar mass of SBP increased firstly and then decreased with the increase of crosslinking time.Scanning electron microscopy(SEM)observation showed that the bulk structure of SBP gradually became fluffy after crosslinking treatment,and obvious linear and honeycomb structures appeared on the surface.The thermal stability of SBP was enhanced after crosslinking treatment,and the mass residue rate increased from 32.37%to 42.20%.However,X-ray diffraction(XRD)results showed that the crystal structure of SBP did not change significantly after crosslinking treatment.Rheological analysis showed that SBP solution exhibited a pseudoplastic behavior,and the influence of shear rate on the viscosity was greatly modified by the presence of sucrose.Moreover,the higher the temperature in the whole shear rate range,the lower the viscosity of SBP.With the extension of crosslinking time,the apparent activation energy Ea of SBP increased from 1.659×104 J/mol reduced to 1.097×104 J/mol,indicating that the effect of temperature on the viscosity of crosslinked SBP is weakened.These results of this study can provide a theoretical reference for the further development and utilization of SBP.