Extraction and Characterization of Sodium Alginate from Egyptian Algae

Abstract Sodium alginate was extracted from Egyptian brown algae using two different methods. In one approach, the brown algae were bleached before extracting the sodium alginate, while in the other method, extraction occurred first, followed by bleaching. The choice of extraction method influenced the yield. The method where sodium alginate was extracted before bleaching resulted in products with higher viscosity. Additionally, the properties of the products and the apparent viscosity of the pastes varied depending on the bleaching agent used. For example, at a shear rate of 6.779 sec − 1 , the apparent viscosity measured 12,520 centipoises with sodium hypochlorite and 8,481.7 centipoise with sodium chlorite. It is advisable to use sodium hypochlorite as the bleaching agent instead of sodium chlorite when extraction precedes bleaching, as it is safer and more cost-effective. All sodium alginate pastes mentioned demonstrate a decrease in apparent viscosity as the shear rate increases. Samples produced with a liquor ratio of 1:10 appeared whiter than those with a ratio of 1:7.5. The resulting products display non-Newtonian pseudoplastic behavior. The method used for extracting sodium alginate from raw algae has a significant impact on the apparent viscosity of the final product.