Molecular and rheological characterization of carrageenan solutions extracted from Kappaphycus alvarezii.

This study evaluates and relates the molecular and rheological characteristics of native carrageenan obtained from Kappaphycus alvarezii seaweed. Native carrageenan was extracted by a differentiated methodology by atomization drying process, which reduces the time for obtaining carrageenan dry powder and minimizes costs and environmental damages. Rheological properties of native carrageenan were compared with a commercial carrageenan grade. Molecular properties were performed by SAXS and GPC analysis and the rheological properties by DMTA and stress relaxation tests. Molecular analysis proved a folded and compact molecular structure and indicated the presence of chains with different molecular weights for native carrageenan. The results obtained showed that the helix-coil transition occurs at temperature about 50 °C. The native and commercial grade carrageenan presented the characteristic of viscoelastic materials and their gel properties show a higher contribution from solid elastic component, and the initial force (F(0)) was higher in commercial carrageenan than native one.