In situ real-time rheological characterization of alginate gelation

流变学中的一个具有挑战性的问题是表征在物理过程中经历快速瞬时结构变化的材料，例如多糖凝胶。为了研究这一过程的动力学，需要可靠的实时流变学监测。本研究项目的科学目标是通过一种新的流变学方法来阐明海藻酸盐的凝胶动力学。通过向样品中瞬时注入二价阳离子，将在原位研究多糖浓度、钙与羧酸根离子的摩尔比、阳离子类型和离子强度的影响。为了实现这样的输液，必须对放置藻酸盐溶液的流变仪底座进行改装。为了证明我们的概念，定制的原型基础已经成功地使用1和1.5wt.%海藻酸盐的水溶液进行了测试。成功地记录了多糖对钙离子存在的瞬时响应。除了原位的流变特性外，还将使用光学显微镜同步记录微观结构的变化。这种结合的方法可以为海藻酸盐的凝胶化动力学提供新的见解。这项研究的结果也具有工业意义，因为这种天然多糖在食品、化妆品和制药行业中有许多应用。

One challenging issue in rheology is to characterize materials undergoing fast transient structural changes during a physical process such as the gelation of polysaccharides. To investigate the kinetics of such a process, reliable real-time rheological monitoring is required. The scientific objective of this research project is to elucidate the gelation kinetics of alginate by means of a novel rheological approach. The impact of the polysaccharide concentration, the molar ratio of calcium to carboxylate ions, the cation type, and the ionic strength will be studied in situ by performing an instant infusion of divalent cations into the samples. To achieve such an infusion, the rheometer base, where the alginate solutions will be placed, must be modified. To provide a proof for our concept, the custom-made prototype base has been successfully tested using aqueous solutions of 1 and 1.5 wt.% alginate. The instant response of the polysaccharide to the presence of the calcium ions could be successfully recorded. In addition to the in-situ rheological characterization, the microstructural changes will simultaneously be recorded using optical microscopy. The combined approach can provide new insights into the gelation kinetics of alginate. The findings of this study are also of industrial relevance as this natural polysaccharide is used in many applications in the food, cosmetic, and pharmaceutical industries.