酸性条件下低酯果胶对酪蛋白酸钠流变特性及微观结构的影响

Effects of low methoxyl pectin on rheological properties and microstructure of sodium caseinate in acidic conditions

以酪蛋白酸钠为原料,在pH值为4.0,质量浓度为4 g/100mL的酪蛋白酸钠中分别添加0、0.3、0.6、0.9、1.2、1.5 g/100mL的低酯果胶,考察低酯果胶对酪蛋白酸钠溶液流变特性及微观结构的影响。结果表明,低酯果胶对酪蛋白酸钠溶液的流变特性有较大影响。随着低酯果胶添加量的增加,复合体系流体指数n下降,稠度系数K逐渐增大,表现出典型的假塑性流体的特征,在1.5 g/100mL的添加量时,体系黏弹性表现为最佳。Zeta电位以及粒径大小的结果表明,随着果胶的加入体系多糖与蛋白质间静电吸引力增大,果胶吸附层厚度增大,复合物平均粒径增大。微观结构观察发现,体系结构随着果胶浓度的增大,从球形蛋白簇结构变成分支较细且致密的网状结构,当果胶加入量达到1.5 g/100mL时,体系固性特征最为明显。

The results showed that 0,0.3,0.6,0.9,1.2,1.5 g/100mL of low methoxyl pectin were added to sodium caseinate in the presence of sodium caseinate as the raw material.Effects of low methoxyl pectin on rheological properties and microstructure of sodium caseinate solution were studied.The results showed that low methoxyl pectin had a great influence on the rheological properties of sodium caseinate solution.With the increase of the amount of low methoxyl pectin,the fluid index n of the composite system decreases and the consistency coefficient K increases gradually,which shows the characteristics of the typical pseudoplastic fluid.The viscoelasticity of the system was the best at 15 g/100mL of the pectin.The Zeta potential and particle size showed that the average particle size of the pectin was increased with the increase of the electrostatic attraction between polysaccharide and protein.Microstructure observation revealed that with the increase of pectin concentration,the structure of the protein system changed from globular to branched network structure.When the pectin content reached 15 g/100mL,the solidification characteristics of the system were the most obvious.