Physico-chemical characterization of alginates isolated from a TunisianPadina pavonicaalgae as a sustainable biomaterial

This study focuses on the physico-chemical characterization of an alginate extracted from seaweed (Padina pavonica) collected on the Tunisian coast. Since alginates display a broad variety of applications, especially in the food and pharmaceutical fields, their quality requires a high certain standard of purity and an accurate knowledge of their composition and structure. With this aim, once extracted the Na-alginate was purified and then characterized for comparison with a commercially available alginate. Thermal analyses (TGA and DSC) were performed to evaluate the water content, i.e. the moisture loss and the thermal stability of this polysaccharide. Spectroscopic investigations demonstrated similarities but also significant differences between the two samples. NMR spectroscopy enabled determination of the mannuronic/guluronic (M/G) ratio, which happened to be lower for the alginate extracted fromP. pavonicaalgae. SEC, performed in water as eluent, was implemented for determination of the average molecular weight of these water-soluble polymers and revealed 6-fold higher molecular weights (M(n)andM(w)) than the commercial reference. (c) 2020 Society of Chemical Industry