Incorporation of κ-carrageenan improves the practical features of agar/konjac glucomannan/κ-carrageenan ternary system

Three materials (agar, konjac glucomannan (KGM) and x-carrageenan) were used to prepare ternary systems, i.e., sol-gels and their dried composites conditioned at varied relative humidity (RH) (33%, 54% and 75%). Combined methods, e.g., scanning electron microscopy, small-angle X-ray scattering, infrared spectroscopy (IR) and X-ray diffraction (XRD), were used to disclose how x-carrageenan addition tailors the features of agar/KGM/x-carrageenan ternary system. As affirmed by IR and XRD, the ternary systems with x-carrageenan below 25% (agar/KGM/carrageenan, 50:25:25, m/m) displayed proper component interactions, which increased the sol-gel transition temperature and the hardness of obtained gels. For instance, the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart. These gels were dehydrated to acquire ternary composites. Compared to agar/KGM composite, the ternary composites showed fewer crystallites and nanoscale orders, and newly-formed nanoscale structures from chain assembly. Such multi-scale structures, for composites with x-carrageenan below 25%, showed weaker changes with RH, as revealed by especially morphologic and crystalline features. Consequently, the ternary composites with less x-carrageenan (below 25%) exhibited stabilized elongation at break and hydrophilicity at different RHs. This hints to us that agar/KGM/x-carrageenan composite systems can display series applications with improved features, e.g., increased sol-gel transition point.(c) 2023 Beijing Academy of Food Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study found that the addition of x-carrageenan to agar/KGM ternary systems can tailor the properties of the gels, increasing their hardness and forming nanostructures. Ternary composites with less than 25% x-carrageenan content exhibit stabilized elongation at break and hydrophilicity.