Sodium Alginate is the sodium salt of alginic acid, a linear copolymer of beta-D-mannuronic acid and alpha-L-guluronic acid residues. It is commercially extracted from brown seaweed species such as Laminaria, Macrocystis, and Ascophyllum through alkaline extraction followed by precipitation.
The M/G ratio determines gel properties — high guluronic acid content produces firm, brittle gels with calcium, while high mannuronic acid yields softer, more elastic gels. Alginate is approved as E401 (sodium alginate), E402 (potassium alginate), and E404 (calcium alginate) under EU regulations, and holds GRAS status with the FDA. JECFA has established an ADI of 'not specified' indicating its excellent safety profile.