魔芋葡甘聚糖与黄原胶复配凝胶的协同作用及其流变特性

The Synergy of Mixed Gels of Konjac Glucomannan and Xanthan and Its Rheological Behavior

研究魔芋葡甘聚糖与黄原胶复配凝胶的协同作用及其流变特性。研究表明,魔芋葡甘聚糖与黄原胶复配比低于3∶7时,随魔芋葡甘聚糖含量的增加,复配凝胶的储能模量G′和凝胶强度逐渐增大;当魔芋葡甘聚糖与黄原胶复配比高于3∶7时,随魔芋葡甘聚糖含量的增加复配凝胶的储能模量G′逐渐减小,凝胶强度逐渐减弱,且不同复配比的复配凝胶的变化趋势不随总质量分数而变化;当魔芋葡甘聚糖与黄原胶复配比在3∶7时的协同作用最大,凝胶强度最强。通过对不同复配比的复配凝胶在线性黏弹区内的稳态储能模量Gc′与临界应变值随总质量分数变化的曲线进行拟合,发现两者随总质量分数的变化符合power-law模型Gc′∝Cn,γc∝Cn′,魔芋葡甘聚糖与黄原胶复配比在1∶9～4∶6之间,幂律系数n随魔芋葡甘聚糖含量的增加而减小,说明在此复配比范围黄原胶对复配凝胶起主导作用;当两者复配比高于4∶6时n值随魔芋葡甘聚糖含量的增加而增加,说明魔芋葡甘聚糖对复配凝胶起主导作用;n’值均为负值且始终随魔芋葡甘聚糖含量的增加而增大,说明总质量分数越高复配凝胶的临界应变值越小,凝胶的韧性越弱;魔芋葡甘聚糖含量越高复配凝胶的临界应变值受总质量分数的影响越小。温度扫描试验表明,不同复配比的复配凝胶在加热过程中表现出相同的趋势,即随着温度的升高G′逐渐降低,在60℃左右达到平衡;冷却过程中复配凝胶的凝胶化开始,温度随黄原胶含量的增加而升高。蠕变试验表明,复配凝胶的瞬时弹性系数E1在两者复配比为5∶5时达到最大值,其它复配比条件下随魔芋葡甘聚糖含量的增加而减小,延迟弹性系数E2和黏性系数η1均在魔芋葡甘聚糖与黄原胶复配比等于3∶7时达到最大值。

The synergy of mixed gels of konjac glucomannan and xanthan and its rheological behavior were studied in this paper The results show that： When the ratio of KGM with XG lower than 3 ∶ 7, the strength of mixed gels increase with the increase of the content of KGM. When the ratio of KGM with XG higher than 3 ∶ 7, the strength of mixed gels decrease with the content of KGM. The tendency of different ratio of mixed gels is independent of concentration. The maximum interaction occur at the ratio of 3 ∶ 7 of KGM and XA. By fitting the curves of the stable storage modulus Gc′ in linear viscoelastic region and the critical strain values with the concentration, it can be found that both of them are consistent with the power-law model as Gc′∝Cn,γc∝Cn′. When the ratio of KGM with XG between 1 ∶ 9 and4 ∶ 6, the power law coefficient n decrease with the increase of content of KGM, which indicate the XG has high functionality to physical gels. When the ratio of KGM with XG beyond 4 ∶ 6, the value of n increase with the increase of content of KGM, which indicate the KGM has high functionality to physical gels. The value of n′ are always negative and increase with the increase of the content of KGM, which indicate critical strain become smaller with the increase of concentration. And with the increase of content of KGM the influence of concentration to critical strain is decrease. Temperature scanning experiments show that the different ratio of KGM/XG mixed gel＇s curve of G′ with temperature is similar. The storage modulus G′ decrease with increase of temperature and become steady when the temperature reached 60℃. The gelation temperature in the cooling process increase with the increase of XA content. Creep tests showed that KGM/XG mixed gel＇s instantaneous elastic coefficient E1 achieve maximum in the ratio of KGM/XG=5 ∶ 5. The value of E1 decrease with increase of content of KGM. The value of delay elastic coefficient E2 and the coefficient of viscosity η1 all achieve maximum in the ratio of KGM/XG=3 ∶ 7.