The gelling of κ-carrageenan in light and heavy water

Gels of κ-carrageenan were prepared in H2O and D2O. Rheological measurements revealed that in heavy water the elastic modulus is substantially higher. From the rheological view point, this result indicates the formation of a higher number of physical-crosslinking points in the structure of the gel. These crosslinking points are mainly associated with the aggregation of the double-helix of the κ-carrageenan, which is enhanced in D2O. The thermal stability of the gels in both solvents (relative to the sol–gel transition) was also investigated by using polarimetric measurements (to measure the relative fraction of helix–coil) and micro-differential scanning calorimetry (micro-DSC). The results obtained using these techniques are very consistent and allow us to propose a model to explain the differences for the gels formed in light and heavy water based on the degree of double-helix aggregation.

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