Biological Process to Valorise Marine Algae

Seaweeds are main sources of marine polysaccharides. Marine polysaccharides, such as agar, alginates and carrageenans are economically the most important products from macroalgae or seaweeds. Carrageenans, marine polysaccharides extracted from red algae are widely used in food, pharmaceutical, cosmetic, textile and printing industries as coagulate agent, stabilizer and gelling agent. Extraction of carrageenan is usually carried out by alkali treatment, but it may have negative impact to the environment. Carrageenan extraction can be processed biologically using microorganisms, such as marine fungi. The aim of this research was to obtain carrageenan from red alga (Kappaphycus alvarezii) using marine fungi and to evaluate the effect of pretreatment on the quality of carrageenan. The study was conducted in three steps including pretreatment of algae, hydrolysis of algae using marine endophytic fungi, and characterization of the carrageenan. Two marine fungi were used to hydrolyze the seaweeds. The best pretreatment was hydrolysis of dried seaweed using fungus RS6A and gelatinization by heating for 20 minutes (RK20). The yield of carrageenan was 71.28%. The gel strength of the carrageenan was 43.35 gf. The chemical and physical characteristics of carrageenan (RK20) met the standard of carrageenan according to FAO.