Physics of agarose fluid gels: Rheological properties and microstructure.
Physics of agarose fluid gels: Rheological properties and microstructure.
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DOI：
10.1016/j.crfs.2021.06.003
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发表时间：
2021
影响因子：
6.3
通讯作者：
Vilgis TA
中科院分区：
文献类型：
--
作者：
Ghebremedhin M;Seiffert S;Vilgis TA
琼脂糖是一种强凝胶多糖，是用于优化多种食品粘弹性的常用成分。通过氢键聚集双螺旋，同时在静止条件下冷却，形成坚固而易碎的凝胶。然而，这种行为可以通过操纵加工条件即剪切来改变。例如，在剪切下的凝胶化导致具有大表面积的微凝胶颗粒，这又导致完全不同的流变性质和质地。这种流体凝胶显示出在吞咽困难患者的食物和饮料的质地改变中起重要作用。在该研究中，考虑了不同浓度的琼脂糖流体凝胶（0.5%wt、1%wt和2%wt）。微凝胶颗粒的流变学测量表明，随着浓度的增加，储能模量和损耗模量增加。然而，1重量%的流体凝胶在低剪切范围内表现出最低的粘度和最短的LVE范围。此外，还通过光学显微镜和粒度分析研究了对凝胶颗粒的微观结构和尺寸的影响。据观察，随着琼脂糖浓度的增加，颗粒尺寸和无序链在颗粒表面的减少。基于我们的研究结果，我们提出了具体的模型，表明颗粒大小的影响，浓度和“毛”的预测上的流变学和摩擦学性能，可以帮助理解的差异，流体凝胶的特性。琼脂糖流体凝胶的形成与浓度、温度和剪切速率的关系。研究了琼脂糖凝胶在剪切作用下凝胶化过程中的竞争机理。所得的凝胶颗粒结构、它们的尺寸和形状随浓度而变化。网络结构、颗粒尺寸和形状影响流变学和摩擦学行为。流体凝胶提供独特的摩擦、粘度和粘弹性行为特性。
Agarose, a strongly gelling polysaccharide, is a common ingredient used to optimize the viscoelastic properties of a multitude of food products. Through aggregation of double helices via hydrogen bonds while cooling under quiescent conditions it forms firm and brittle gels. However, this behavior can be altered by manipulating the processing conditions viz shear. For example, gelation under shear leads to microgel particles with large surface area, which in turn leads to completely different rheological properties and texture. Such fluid gels are shown to play an important role in texture modification of foods and beverages for dysphagia patients. In this study, different concentration of agarose fluid gel (0.5 % wt, 1 % wt and 2 % wt) were considered. Rheological measurements of the microgel particles showed an increase of storage and loss modulus with increasing concentration. However, 1 % wt fluid gel exhibited the lowest viscosity in the low shear range and the shortest LVE range. Furthermore, the effect on the microstructure and size of gel particles were also investigated by using light microscopy and particle size analysis. It was observed that as the concentration of agarose increased the particle size and unordered chains present at the particle surface decreases. Based on our results, we propose specific models suggesting the impact of the particle size, the concentration and the “hairy” projections on the rheological and tribological properties that could help in understanding the differences in characteristics of fluid gels. Formation of agarose fluid gels in dependence on concentration, temperature and shear rate. Competing mechanism during gelation under shear of agarose fluid gels was studied. The resulting gel particle structures, their size and shape vary with concentration. Network structures, particle size and shape affect the rheological and tribological behavior. Fluid gels provide unique properties of friction, viscosity and viscoelastic behavior.
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