Effect of salt addition on iota-carrageenan solution properties

Polysaccharides are versatile biopolymers available to mankind for multiple uses ranging from achieving desirable food texture to serving as tissue scaffolds. Their complete utility, however, is yet unrealized by the lack of precise knowledge on their structure function relationships. Herein, sodium iota-carrageenan (IC) is selected as a model polysaccharide and its viscoelastic properties, molecular assembly, water mobility, microstructure and melting behavior have been analyzed to understand the salt effect. Results demonstrate that while the storage modulus, gel-sol transition temperature, thermal stability and helical aggregation increase, water mobility decreases, with salt addition; the initial no-salt IC ordered microstructure transforms to an irregular structure composed of larger cavities. These observations are intimately associated with the dynamic interactions persistent at the molecular level between the anionic IC chains and salt ions. Overall, results help to move a step closer to realize the functional behavior of iota-carrageenan and by extrapolation to other polysaccharides as well.

Automated summary

The addition of salt enhances the storage modulus, gel-sol transition temperature, thermal stability, and helical aggregation of polysaccharides, while decreasing water mobility and transforming the microstructure. These changes are intimately associated with dynamic interactions at the molecular level.