交联程度对木薯淀粉特性的影响

Effect of Cross-Linking Degree on Characteristics of Tapioca Starch

为探讨交联作用对木薯淀粉凝胶的影响,利用快速黏度分析仪和动态流变仪研究不同交联度木薯淀粉的糊化特性和流变特性。黏度特性测试结果表明,随着交联度的增加,交联木薯淀粉的回生值和最终黏度先增加后减小,崩解值减小。由静态流变测试结果可知,不同交联木薯淀粉屈服应力T0大于0,流动指数n均小于1,表明该实验条件下木薯淀粉糊均为屈服-假塑性流体。淀粉糊(质量分数为6%)动态流变测试结果表明,在0.1~10.0 Hz频率范围内,交联木薯淀粉的储能模量(G’)和损耗模量(G")均高于原木薯淀粉G’和G";在4℃条件下老化2 h,适当的交联可以使木薯淀粉G’升高,损耗角正切值(tanδ=G"/G’)降低。淀粉糊(质量分数为15%)动态流变测试结果表明,在整个升温和降温过程中,交联木薯淀粉的G’和G"大于原木薯淀粉,降温过程中,淀粉凝胶的G’随交联度增加迅速增加,表现出更优越的凝胶特性。

In order to investigate gel properties of cross-linked tapioca starch,the pasting and rheological properties of tapioca starch with different cross-linking degrees were determined using a rapid viscosity analyzer(RVA)and a dynamic rheometer.Viscosity measurement showed that final viscosity and setback first increased and then decreased with increasing cross-linking degree,while breakdown continuously decreased.The steady-state rheological properties showed that all tapioca starch pastes with different cross-linking degrees were pseudo-plastic non-Newtonian fluids(T0>0,n<1).The dynamic rheological properties demonstrated that the storage modulus(G')and loss modulus(G”)of the cross-linked tapioca starch gel(6%m/m)were improved throughout the whole frequency range(0.1～10.0Hz)compared to the raw starch gel.The G'of the properly cross-linked tapioca starch gel was increased,while tanδwas decreased during2h aging at4℃.Compared to the raw starch gel,the G'and G”of the cross-linked tapioca starch gel(15%m/m)were improved during both heating and cooling.During cooling,the G'was increased rapidly with increasing cross-linking degree suggesting improved gel properties.