Rheology and microstructure of κ-carrageenan under different conformations induced by several concentrations of potassium ion
Rheology and microstructure of κ-carrageenan under different conformations induced by several concentrations of potassium ion
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DOI：
10.1016/j.foodhyd.2010.05.003
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发表时间：
2011-01-01
影响因子：
10.7
通讯作者：
Doublier, Jean Louis
中科院分区：
文献类型：
--
作者：
Nunez-Santiago, M. C.;Tecante, Alberto;Doublier, Jean Louis
采用流变学、显微差示扫描量热法（micro-DSC）和共聚焦显微镜研究了60 ℃、25 ℃和9 ℃下K-卡拉胶溶液在不同构象下的粘弹行为、无序-有序转变和微观结构。在60 ℃和25 ℃下，分别含有0-80 mmol/dm（3）和0-5 mmol/dm（3）KCl的0.5% κ-卡拉胶的流变行为是无规卷曲聚合物的粘弹性溶液的典型。在9 ℃和低于约7.0 mmol/dm（3）的临界离子浓度时，κ-角叉菜胶采用有序构象，其中螺旋结构不聚集，因此不形成自支撑凝胶。多糖硬度的变化估计从特性粘度变化作为离子含量的函数。在有序状态下，刚度比在无序状态下更高，而液体状的粘弹性行为仍然表现出。在25 ℃下，在0.5%的κ-角叉菜胶中，将KCl从0增加到300 mmol/dm（3）产生刚性增加的凝胶。然而，超过100 mmol/dm（3），这种增加是微不足道的。共聚焦图像证明了一个三维网络，其连续性取决于多糖和盐的浓度。这些观察结果与κ-角叉菜胶浓度在0.05- 1%范围内获得的自支撑凝胶的流变行为一致。(C)2010爱思唯尔有限公司保留所有权利。
Rheology, micro-DSC and confocal microscopy were used to study the effect of potassium ion on the viscoelastic behavior, disorder-order transition and microstructure, respectively, of kappa-carrageenan in solution under different conformations at 60, 25 and 9 degrees C. At 60 and 25 degrees C the rheological behavior of 0.5% kappa-carrageenan with 0-80 mmol/dm(3) and 0-5 mmol/dm(3) KCl, respectively, was typical of viscoelastic solutions of random coiled polymers. At 9 degrees C and below a critical ionic concentration of about 7.0 mmol/dm(3), kappa-carrageenan adopted an ordered conformation in which helical structures did not aggregate and hence did not form self-supporting gels. Changes in polysaccharide stiffness were estimated from intrinsic viscosity variations as a function of ionic content. In the ordered state, the stiffness was higher than in the disordered state, whereas a liquid-like viscoelastic behavior was still exhibited. In 0.5% kappa-carrageenan at 25 degrees C, increasing KCl from 0 to 300 mmol/dm(3) produced gels of increasing rigidity. However, above 100 mmol/dm(3) such increase was marginal. Confocal images evidenced a three-dimensional network whose continuity depends on polysaccharide and salt concentrations. These observations are consistent with the rheological behavior of the self-supporting gels obtained with kappa-carrageenan concentrations in the range of 0.05-1%. (C) 2010 Elsevier Ltd. All rights reserved.