Molecular origin for rheological characteristics of native gellan gum
Molecular origin for rheological characteristics of native gellan gum
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DOI：
10.1007/s00396-009-2112-2
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发表时间：
2009-09
影响因子：
2.4
通讯作者：
M. Tako;T. Teruya;Y. Tamaki;T. Konishi
中科院分区：
文献类型：
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作者：
M. Tako;T. Teruya;Y. Tamaki;T. Konishi
核磁共振氢谱表明，天然结冷胶的α-鼠李糖残基同时参与了少量的4C 1-吡喃糖构象和大量的1C 4-吡喃糖构象，而脱酰化的结冷胶的α-鼠李糖残基几乎全部参与了4C 1-吡喃糖构象。天然结冷胶的流动曲线在0.2%以上表现出塑性行为。随着温度的升高，弹性模量保持在恒定值，直到40 °C，然后迅速下降。弹性模量随着CaCl 2（6.8mM）的添加而增加，并且随着温度升高至65 °C而保持恒定值，然后迅速降低。在脱酰结冷胶中加入CaCl 2后，弹性模量增加。天然结冷胶的弹性模量显示出比尿素（4.0 M）存在下的水溶液中的弹性模量更大的值。提出了天然结冷胶分子在Ca+2存在下的分子内和分子间缔合。
The1H-nuclear magnetic resonance spectrum showed that thel-rhamnosyl residues of native gellan gum were coinvolved in both a small number of4C1-pyranose conformations and a large number of1C4-pyranose conformations, whereas for deacylated polymer, almost of the residues were involved in4C1-pyranose conformation. The flow curves of native gellan gum showed plastic behavior above 0.2%. The elastic modulus stayed at a constant value with increase in temperature up to 40 °C, then decreased rapidly. The elastic modulus increased with addition of CaCl2(6.8 mM) and stayed constant value with increase in temperature up to 65 °C, then decreased rapidly. The stronger elastic modulus was observed in deacylated gellan gum with addition of CaCl2. The elastic modulus of native gellan gum showed larger value than that in aqueous solution in the presence of urea (4.0 M). Intra- and intermolecular associations of native gellan gum molecules in the presence of Ca+2were proposed.