Monteiro Maria Alice Freitas, Faria Bruno, Moraes Izabel Cristina Freitas, Hilliou Loic
Institute for Polymers and Composites, University of Minho, 5800-048 Guimarães, Portugal.
Department of Food Engineering, Faculty of Animal Science and Food Engineering (FZEA), University of São Paulo (USP), Postgraduate Programme in Materials Science and Engineering, Pirassununga 13635-900, SP, Brazil.
Gels. 2025 Feb 22;11(3):157. doi: 10.3390/gels11030157.
A comparison between the gel properties of blends of kappa- and iota-carrageenans (K+Is) and hybrid carrageenans (KIs) with equivalent chemical compositions is here presented. The objective is to assess under which conditions hybrid carrageenans are valuable alternative to blends of kappa- and iota-carrageenans for gelling applications and to contribute to the identification of phase-separated structures or co-aggregated helices. Phase states constructed in sodium chloride and in potassium chloride confirm that KIs build gels under a much narrower range of ionic strength and polysaccharide concentration. Hybrid carrageenans displayed salt specificity, forming gels in KCl but not in NaCl, highlighting their limited gelling potential in Na environments. A two-step gelation mechanism was found in both systems at lower ionic strengths and when iota carrageenan is the major component. The shear elastic moduli of KI gels are overall smaller than those of blends, but the opposite is observed at lower ionic strengths in KCl and in systems richer in iota-carrageenans. The nonlinear elastic properties of gels do not relate to the use of blends or hybrid carrageenans for their formulation. Instead, larger contents in iota-carrageenans lead to gels able to sustain larger strains before yielding to a fluid state. However, these gels are more prone to strain softening, whereas strain hardening is measured in gels containing more kappa-carrageenan, irrespective of their blend or hybrid structure.
本文对具有等效化学组成的κ-卡拉胶和ι-卡拉胶混合物（K+Is）与杂化卡拉胶（KIs）的凝胶特性进行了比较。目的是评估在哪些条件下杂化卡拉胶可作为κ-卡拉胶和ι-卡拉胶混合物用于凝胶应用的有价值替代品，并有助于识别相分离结构或共聚集螺旋。在氯化钠和氯化钾中构建的相态证实，KIs在更窄的离子强度和多糖浓度范围内形成凝胶。杂化卡拉胶表现出盐特异性，在KCl中形成凝胶而在NaCl中不形成，突出了它们在钠环境中有限的凝胶化潜力。在较低离子强度下以及当ι-卡拉胶为主要成分时，在两个体系中均发现了两步凝胶化机制。KI凝胶的剪切弹性模量总体上小于混合物的剪切弹性模量，但在KCl中较低离子强度下以及在富含ι-卡拉胶的体系中观察到相反的情况。凝胶的非线性弹性特性与使用混合物或杂化卡拉胶进行配方无关。相反，ι-卡拉胶含量越高，凝胶在转变为流体状态之前能够承受的应变就越大。然而，这些凝胶更容易发生应变软化，而在含有更多κ-卡拉胶的凝胶中则测量到应变硬化，无论其是混合物还是杂化结构。
