Rheological Properties of Carrageenan Gels

Carrageenans are sulphated polysaccharides extracted from red seaweeds that form thermoreversible gels through a coil-to-helix transition followed by helix aggregation into a three-dimensional network. The gelation process is highly sensitive to temperature, polymer concentration, ionic strength and the nature of counter-ions, all of which influence critical parameters such as the gel point, storage modulus and yield stress. Under oscillatory shear, carrageenan gels exhibit a pronounced elastic plateau (storage modulus G′) at small strains, transitioning to non-linear strain-hardening or strain-softening regimes before yielding. Steady shear tests reveal shear-thinning and thixotropic behaviour, reflecting reversible network breakdown and rebuild. Fine-tuning of network mesh size and junction zone strength by co-polymers or polyols can tailor viscoelasticity for specific applications, ranging from texture modification in foods and controlled drug delivery to scaffold fabrication in tissue engineering and bespoke 3D printing of hydrogel constructs.

Research from Nature Portfolio

Recent studies have elucidated the interplay between conformational ordering and electrostatic complexation in κ-carrageenan systems. During the initial helix formation induced by cooling and specific cations, ion binding can either enhance or inhibit protein–polysaccharide interactions by altering charge density or occupying binding sites. Beyond a critical helix content, chain stiffening becomes dominant, weakening electrostatic complexes and favouring helix–helix association. This dual mechanism has been interpreted through models of double-helix aggregation, providing a molecular-mechanical link that advances our understanding of how ion type and chain rigidity jointly govern gel network formation and stability.

Rheological Properties of Carrageenan Gels publication trend

The graph below shows the total number of articles in rheological properties of carrageenan gels across all publications each year (not limited to Nature Index journals).

Technical terms

Coil-to-helix transition: Reversible conformational change of carrageenan chains from random coils to ordered helices upon cooling or ion binding.

Storage modulus (G′): Measure of elastic energy stored in a gel under oscillatory shear, indicating network rigidity.

Loss modulus (G″): Measure of viscous energy dissipated under oscillatory shear, reflecting internal friction.

Yield stress: Minimum stress required to initiate irreversible flow and breakdown of the gel network.

Sol–gel transition: Point at which a polymer solution transforms into a semi-solid gel, marked by the onset of network percolation.

Thixotropy: Time-dependent decrease in viscosity under constant shear, followed by recovery at rest, characteristic of reversible network structures.

References

1. Structure–Elastic Properties Relationships in Gelling Carrageenans. Polymers (2021).
2. Effects of conformational ordering on protein/polyelectrolyte electrostatic complexation: ionic binding and chain stiffening. Scientific Reports (2016).
3. Thermorheological Behavior of κ-Carrageenan Hydrogels Modified with Xanthan Gum. Fluids (2023).
4. Kinetics of acid hydrolysis of k-Carrageenan by in situ rheological follow-up. Food Hydrocolloids (2023).
5. Linking Processing Parameters and Rheology to Optimize Additive Manufacturing of k-Carrageenan Gel Systems. Gels (2022).
6. Making Polyol Gummies by 3D Printing: Effect of Polyols on 3D Printing Characteristics. Foods (2022).