不同凝固剂诱导大豆蛋白冷凝胶的流变特性及分形结构分析

Fractal Structure and Rheological Properties Analysis of Cold-Set Soy Protein Gel Induced by Different Coagulants

研究不同质量分数凝固剂(GDL,Mg SO4,Ca Cl2,1%~4%)诱导所得大豆蛋白冷凝胶的流变特性和标度行为。结果表明:添加凝固剂后,随时间的延长,所有样品呈明显的凝胶行为,冷凝胶的凝胶强度具有浓度依赖性,随凝固剂质量分数增加而增加;频率扫描曲线对幂率模型的拟合度非常高(R2>0.938),特征值n′和n″值表明冷凝胶为弱凝胶体系;酸诱导冷凝胶热稳定性高,盐诱导凝胶经加热后结构破坏严重;盐诱导凝胶蠕变-恢复率高,盐桥作用明显;不同流变分形模型显示酸盐诱导冷凝胶形成不同的微观结构,由Shih模型可知,GDL诱导凝胶Df值在2.73~2.76之间,Mg SO4诱导凝胶在2.57~2.59之间,Ca Cl2诱导凝胶在2.5~2.69之间,Wu&Morbidelli模型所得值相应较小。凝胶的动态储能模量和分形结构显著受到凝固剂种类和不同质量分数的影响。

The rheological properties and scaling behavior of cold-set soy protein gels induced by different coagulants（GDL, Mg SO4, Ca Cl2, 1%-4%, W/W） has been studied. The results show that： After adding coagulant, all the samples show obvious gelling behavior with the passage of time. The strength of cold gel increased with the increasing of coagulant concentration. Frequency curve of cold-set gel can be highly fit power-law model（R2〉0.938）. Characteristic value n′ and n″ indicates that cold-set gel system is weak gel system. Compared to salt-induced gel, acid-induced gel is higher thermal stability. After heating, the structure of cold-set gel destructed seriously. The creep-recovery rate of salt-induced gel is higher than acid-induced gel. Salt bridges played a decisive role. According to the fractal model,acid-induced gel and salt-induced gel have different microstructures. According to fractal dimension calculated by the Shih model, the Dfvalue of GDL-induced gel is 2.73-2.76, Mg SO4-induced gel is 2.57-2.59, Ca Cl2-induced gel is2.5-2.69. The fractal dimension calculated by Wu Morbidelli model is smaller than Shih model. The dynamic storage modulus and gel fractal structure are significantly affected by the type and concentration of the coagulant.