Potential uses of the brown seaweed Cystoseira humilis biomass: 1- Sodium alginate yield,FT-IR,1H NMR and rheological analyses

Alginates are linear binary co-polymers of β-d-mannuronic acid (m) and α-l-guluronic acid (g),extracted from brown seaweeds and are used in industry for their colloidal properties. this work discusses the results of extraction,spectroscopic characterization and rheological behavior of alginates from the brown seaweed cystoseira humilis harvested from the atlantic coast of el jadida,morocco. the obtained results show that the yield of alginate from c. humilis depending on the used extraction method. for the method based on precipitation with ethanol the yield is about 5.43% dry weight,whereas the precipitation with calcium chloride (cacl2) gives a yield of 19.21% dry weight. the ft-ir spectroscopic analysis showed characteristic peaks corresponding to the various groups present in the both c. humilis and high-quality commercial alginates. the 1h nmr spectroscopy was used to evaluate de quality of the studied polymer and to calculate the proportions of monads,dyads and the relationship between the two uronic acids (fg = 0.41; fm = 0.59; fmg = 0.19; m/g = 1.46). rheological assays demonstrate that c. humilis products a shear-thinning hydrogels except at the lowest concentrations which exhibit a newtonian behavior with a linear relation between apparent viscosity and shear stress.