<![CDATA[Alginate has been widely used in industrial field because of its natural properties as gelling agent. Brownseaweed, especially Sargassum and Turbinaria as the alginate sources are widely grown in Indonesia; butunfortunately there has yet to be any alginate industry in Indonesia. Alginate content in Sargassum isconsidered quite large, about 35%, whereas alginate content in Turbinaria is only around 20-25%. In thisresearch, sodium alginate was isolated from dried brown seaweed (Sargassum sp.) which first passedthrough the acid treatment using 0,5%-b/v HCl and alkaline treatment using 0,5%-b/v NaOH. Extraction wasdone in batch, using 2%-b/v Na2CO3 solvent. The chosen post-treatment method was through the Ca-alginatepath with experimental design Reponse Surface Methods-Central Composite Design with 5 center point. Thevaried variable was the concentration of CaCl2 (0,11 – 2,09 M) and the ratio of CaCl2 solution/alginateextract (0,48 – 4,02 g/g). The result showed that higher concentration of CaCl2 increased the yield, viscosity,and ash content. As the ratio of CaCl2/alginate extract got higher, the viscosity had the tendency to decreaseand the ash content increased. Yield of the obtained sodium alginate powder was 6,95 -30,7%; 1,48 – 11,85cP viscosity; ash content about 18,46 – 52,65%; and water content around 6,14 – 8,32%. The optimumcondition was obtained at CaCl2 concentration of 1,02 M and the ratio of CaCl2/alginate extract about 2,01g/g with 27,72% yield, 11,38 cP viscosity, 19,56% ash content, and 6,14-8,32% water content of sodiumalginate.]]>
