Understanding nanostructural differences in hydrogels from commercial carrageenans: Combined small angle X-ray scattering and rheological studies
Journal article, 2020

Hydrogels from commercial carrageenans (κ-C, ι-C, λ↑-C (high viscosity) and λ↓-C (low viscosity)) were prepared with and without the addition of salts (KCl and CaCl2). FT-IR and 1H NMR characterization evidenced that while the κ-C and ι-C grades were relatively pure carrageenans, the two λ-C grades were λ-, κ-, θ- and μ-carrageenan hybrids. The effect of carrageenan and salt concentration on the hydrogel strength were evaluated through a response surface design and a detailed structural characterization was carried out by small angle X-ray scattering (SAXS) and rheology. The low amount of sulphate substitution in κ-C enabled intramolecular association, giving rise to strong hydrogels, even in the absence of salts. On the other hand, ι-C, λ↑-C and λ↓-C produced much weaker hydrogels and required the addition of salts to induce intramolecular association by ionic cross-linking. SAXS results suggested the formation of similar structures of double helices in κ-C and ι-C with the addition of salts; however, distinct network structures were attained. In the case of κ-C, a Gauss-Lorentz gel model was suitable to describe the hydrogel structure and the addition of K+ promoted the formation of more ordered and densely packed structures. On the other hand, larger but weaker aggregates, with marked periodicity, were observed in ι-C, with Ca2+ inducing the formation of more densely packed networks. The complex composition of the λ-C grades gave rise to more heterogeneous branched network structures, properly described by a correlation length model, where the gelation mechanism was mostly governed by the κ-carrageenan component.

Author

[Person cc0a3fac-4398-4606-917f-f74ca40871ea not found]

CSIC - Instituto de Agroquimica y Tecnologia de los Alimentos (IATA)

[Person 82101963-e25f-4764-86fd-1695fbe14888 not found]

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

[Person c3d93f25-56a3-4f0f-9488-df22c57e32b6 not found]

Teagasc Food Research Centre

[Person 352efd14-89ca-428f-b06a-3cbcbf2f8f7a not found]

CSIC - Instituto de Agroquimica y Tecnologia de los Alimentos (IATA)

[Person d21ac523-abb6-4134-9931-25ae18e61d28 not found]

CSIC - Instituto de Agroquimica y Tecnologia de los Alimentos (IATA)

Algal Research

2211-9264 (ISSN)

Vol. 47 101882- 101882

Subject Categories

Chemical Engineering

DOI

10.1016/j.algal.2020.101882

More information

Latest update

4/24/2020