Caractérisation spectroscopique et rhéologique des alginates de sodium extraits de trois algues marines Phaeophyceae (Dictyopteris polypodioides,Dilophus ligulatus et Halopteris scoparia) de la côte d'El Jadida - Maroc [Spectroscopic and rheological characterization of sodium alginate extracted from three Phaeophycean seaweeds (Dictyopteris polypodioides,Dilophus ligulatus and Halopteris scoparia) from El Jadida shoreline - Morocco]

In morocco,despite the taxonomic richness of the atlantic and mediterranean coastlines,marine flora exploitation is limited to the commercial harvesting of few red algae. in this paper,three pheophycean species,namely dictyopteris polypodioides,dilophus ligulatus and halopteris scoparia,harvested from el jadida coasts - morocco,were analyzed for sodium alginate yield,spectroscopic and rheological properties. the alginate yields for these three species are 21.92,8.8 and 4.16 % dry weight,respectively. ftir-atr spectra of d. polypodioides and d. ligulatus exhibit strong similarity with those of commercial alginate while h. scoparia show atypical spectrum without the required characteristics bands. the rheological tests indicate that all obtained gels exhibit a newtonian behavior with a linear dependency of the shear stress and the shear rate except for d. ligulatus at higher concentrations with non-newtonian sodium alginate fluids. viscosities (η) at 0.5% alginate solutions are about 1.92,1.97 and 1.91 mpa.s respectively for d. polypodioides,d. ligulatus and h. scoparia and increase proportionally with alginate concentration for the three species.