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Drying process of sodium alginate edible films forming solutions studied by LF NMR
Food Chemistry ( IF 8.8 ) Pub Date : 2018-01-05 , DOI: 10.1016/j.foodchem.2018.01.043
Qian Xiao

The dynamics of water in sodium alginate film-forming solutions during drying were investigated by low-field nuclear magnetic resonance. At the beginning of drying, three transverse relaxation times at around 1.74, 28.48 and 305.38 ms were assigned to the tightly bound, moderately bound, and free water, respectively. Moreover, the free water was evaporated, followed by the formation of water cluster in the entangled alginate chains network as the drying process continued (beyond 840 min of drying time). Towards the third stage of drying process, water clusters in alginate samples was disappeared, resulting that loosely bonded waters were constrained within the weak-gel network. The observed three relaxation times revealed the multi-exponential relaxation behavior of water in alginate, which indicated that this polymer exhibited spatial heterogeneity during drying. On the basis of diffusive exchange theory, the dimension range of alginate network decreased from 1.94–23.99 to 1.83–6.62 µm as the alginate films solidified.



中文翻译:

LF NMR研究海藻酸钠可食膜形成溶液的干燥工艺。

通过低场核磁共振研究了干燥过程中藻酸钠成膜溶液中水的动力学。在干燥开始时,分别将约1.74、28.48和305.38 ms的三个横向松弛时间分配给紧密结合,中等结合和游离水。此外,随着干燥过程的继续(超过840分钟的干燥时间),游离水被蒸发,随后在纠缠的藻酸盐链网络中形成水团簇。在干燥过程的第三阶段,藻酸盐样品中的水团消失了,导致松散结合的水被限制在弱凝胶网络中。观察到的三个弛豫时间揭示了藻酸盐中水的多指数弛豫行为,这表明该聚合物在干燥过程中表现出空间异质性。根据扩散交换理论,随着藻酸盐膜的凝固,藻酸盐网络的尺寸范围从1.94–23.99减小至1.83–6.62 µm。

更新日期:2018-01-05
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