Physicochemical Characterisation of Alginate from Malaysian Brown Seaweeds

Nine species of brown seaweeds have been studied to obtain information on the percentage yield of alginate and their physicochemical properties. The percentage yield varied between 18 to 35% when extracted in 0.1 M Na2CO3 for 24h. Higher yields were observed when the seaweed samples were extracted in EDTA, CDTA, sodium phosphate and sodium citrate solution. Intrinsic viscosities and molecular weights varied between 2.15 to 14.40 dl/g and 1.05 to 9.49 x 105 dalton, respectively. Pre-treating the seaweeds with formaldehyde and ethanol prior to extraction with sodium carbonate, or extraction under neutral conditions with selected calcium ion sequestrants, gave alginate with higher intrinsic viscosity and molecular weight. The M/G ratio for all the samples studied were in the range of 0.42 to 2.10. Based on the physicochemical properties and percentage yield, Sargassum spp. are found to be good sources for alginate production.