Isolasi Alginat Rumput Laut Coklat (Sargassum sp.) menggunakan Jalur Kalsium Alginat

Abstract

Alginate has been widely used in industrial field because of its natural properties as gelling agent. Brown
seaweed, especially Sargassum and Turbinaria as the alginate sources are widely grown in Indonesia; but
unfortunately there has yet to be any alginate industry in Indonesia. Alginate content in Sargassum is
considered quite large, about 35%, whereas alginate content in Turbinaria is only around 20-25%. In this
research, sodium alginate was isolated from dried brown seaweed (Sargassum sp.) which first passed
through the acid treatment using 0,5%-b/v HCl and alkaline treatment using 0,5%-b/v NaOH. Extraction was
done in batch, using 2%-b/v Na2CO3 solvent. The chosen post-treatment method was through the Ca-alginate
path with experimental design Reponse Surface Methods-Central Composite Design with 5 center point. The
varied variable was the concentration of CaCl2 (0,11 – 2,09 M) and the ratio of CaCl2 solution/alginate
extract (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 decrease
and the ash content increased. Yield of the obtained sodium alginate powder was 6,95 -30,7%; 1,48 – 11,85
cP viscosity; ash content about 18,46 – 52,65%; and water content around 6,14 – 8,32%. The optimum
condition was obtained at CaCl2 concentration of 1,02 M and the ratio of CaCl2/alginate extract about 2,01
g/g with 27,72% yield, 11,38 cP viscosity, 19,56% ash content, and 6,14-8,32% water content of sodium
alginate.