Abstract The issue addressed here is whether kappa carrageenan (κ-car) and iota carrageenan (ι-car) mixed in aqueous solution microphase separate during gelation as has been claimed in the literature. Rheological properties and microstructure of individual κ-car and ι-car solutions as well as their mixtures were studied at different concentrations (5, 10, 20 g/L) in the presence of CaCl2 (0–100 mM). Mixtures showed a two-step gelation process at gelation temperatures (Tc) that coincided with those of corresponding individual κ-car and ι-car solutions. However, the stiffness of the mixed gels was much higher than the sum of the corresponding individual gels. Confocal laser scanning microscopy (CLSM) and turbidity measurements showed that the κ-car gel was always more heterogeneous than the ι-car gel, but less in the mixture than in the individual systems. The results show that microphase separation of ι-car and κ-car in mixed gels is highly unlikely. It is suggested that the increased stiffness of the mixed gels is caused by co-aggregation of κ-car and ι-car or a different structure of the κ-car formed in the mixture.

中文翻译：

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iota和κ-角叉菜胶混合物的流变学和微观结构

摘要 这里解决的问题是，如文献中所声称的，在凝胶化期间混合在水溶液微相中的κ角叉菜胶（κ-car）和ι角叉菜胶（ι-car）是否分离。在 CaCl2 (0–100 mM) 存在下，研究了不同浓度 (5, 10, 20 g/L) 的单个 κ-car 和 ι-car 溶液及其混合物的流变特性和微观结构。混合物在胶凝温度 (Tc) 下显示出两步胶凝过程，该温度与相应的单个 κ-car 和 ι-car 溶液的温度一致。然而，混合凝胶的刚度远高于相应的单个凝胶的总和。共聚焦激光扫描显微镜 (CLSM) 和浊度测量表明，κ-car 凝胶总是比 ι-car 凝胶更异质，但在混合物中比在单个系统中少。结果表明，ι-car 和κ-car 在混合凝胶中的微相分离是极不可能的。这表明混合凝胶的刚度增加是由 κ-car 和 ι-car 的共聚集或混合物中形成的 κ-car 的不同结构引起的。