Valorization of brown algae (Cystoseira caespitosa) from local region in Algeria for sodium alginate extraction and their application in the immobilization of microbial pectinases

Sodium alginate were extracted from brown algae (Cystoseira Caespitosa) collected from Algerian Mediterranean coast. the physicochemical characteristic of sodium alginate showed that the average yield was 12% and the average molecular masse was 9000Da calculated using intrinsic viscosity data. Fourier transform infrared spectroscopy was used to characterize the extracted powder of sodium alginate, COO- and C-O-C were evident in the finger print region, the ratio of guluronic acid (G) / mannuronic acid (M) was recorded to be 0.91. This polysaccharide were used to immobilize crude pectinolytic enzymes synthesized by a strain of Aspergillus niger sp. The immobilization was carried out by dropwise introduction of alginate-enzyme mixture into a 0.2M CaCl 2 solution, by this technique, alginates shrinking in the form of spherical beads. The calcium alginate beads have been analyzed using scanning electron microscopy (SEM), observation under SEM showed that the beads have a rough surface and the enzymes were successfully included in the beads. The immobilization efficiency was about 83.9% and the immobilized enzyme could be reused in 4 cycles keeping 42,14% of its initial activity. The beads were successfully used for apple juice clarification.