Annealing induced gelation of xanthan/water systems
Annealing induced gelation of xanthan/water systems
复制标题
退火诱导黄原胶/水体系的凝胶化
DOI：
10.1016/s0032-3861(97)00266-8
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发表时间：
1998
期刊：
影响因子：
4.6
通讯作者：
H. Hatakeyama
中科院分区：
文献类型：
--
作者：
Tadashi Yoshida;M. Takahashi;T. Hatakeyama;H. Hatakeyama
采用落球法（FBM）和差示扫描量热法（d.s.c）研究了在高于凝胶-溶胶转变温度的温度下退火对黄原胶/水凝胶化过程中结形成的影响。黄原胶在室温下的水溶液是不均匀的。虽然在随后的冷却后形成了凝胶状溶液，但这些溶液不能被归类为凝胶。相反，当溶液在40°C退火时，通过随后的冷却形成牢固的凝胶。FBM清晰地观察到凝胶-溶胶转变温度。随着退火时间的延长，tg -s从27℃开始逐渐升高，趋于恒定值，即1 wt%样品为33℃，2 wt%样品为40℃。退火时间取决于样品浓度和退火温度。在0 ~ 12 h的退火过程中，虽然FBM观察到tg -s的稳定增加，但dsc估计的非冻结水的数量出现了波动。这种现象被解释为溶液的均质化，即黄原胶分子通过退火解吸非冷冻水而脱离其分子组装。上述结果表明，黄原胶/水溶液在溶胶状态下完全退火后形成凝胶态。
The effect of annealing at a temperature higher than the gel-sol transition temperature on the junction formation in the gelation process of xanthan/water solutions was investigated by the falling ball method (FBM) and differential scanning calorimetry (d.s.c.). Aqueous solutions of xanthan dissolved at room temperature were inhomogeneous. Although gel-like solutions were formed after subsequent cooling, the solutions could not be categorised as a gel. In contrast, when the solutions were annealed at 40°C, firm gels were formed by subsequent cooling. The gel-sol transition temperature (Tg-s) was clearly observed by FBM. It was found that Tg-sgradually increased from 27°C with increasing annealing time and approached a constant value, i.e. 33°C for 1 wt% sample and 40°C for 2 wt% sample. The annealing time, where Tg-slevelled off, depended on sample concentration and annealing temperature. During annealing from 0 to 12 h, it was observed that the amount of non-freezing water estimated by d.s.c. fluctuated, although a steady increase of Tg-swas observed by FBM. This phenomenon is interpreted as a homogenisation of the solution, i.e. xanthan molecules become free from their molecular assembly through desorption of non-freezing water by annealing. The above results indicate that xanthan/water solutions form the gel state when they are fully annealed in the sol state.