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Sodium alginate

Sodium alginate suppliers and sourcing guide

Sodium alginate is the sodium salt of alginic acid, a polysaccharide extracted from brown seaweeds such as Laminaria, Macrocystis and Ascophyllum. The seaweed is extracted with alkali, the alginate is precipitated as alginic acid or calcium alginate, purified and neutralized with sodium carbonate, then dried and milled. It thickens water and forms gels when it meets calcium.

See suppliersWhat to ask for on the COA
Also known as
E401 · algin · sodium salt of alginic acid · alginate
Facts checked
November 2026

Forms and grades of sodium alginate

Suppliers sell different products under the same name. Specify the one you need.

  • Viscosity grades

    Low, medium and high viscosity grades, set by molecular weight.

  • High-G and high-M grades

    Ratio of guluronic to mannuronic acid; high-G gives firmer, more brittle calcium gels.

  • Mesh sizes

    Coarser and finer grinds that trade dispersibility against hydration speed.

  • Pharmaceutical grade

    Grades made to USP-NF or Ph. Eur. monographs for tablets and capsules.

What to check on the COA

Compare each result with your own specification when the lot arrives.

Assay
Alginate content on a dry basis by carbon dioxide evolution (decarboxylation) per the FCC method.
Viscosity
Brookfield viscosity of a 1% solution.
Loss on drying and ash
Moisture by oven drying, plus ash and water-insoluble matter.
Heavy metals
Lead and arsenic by ICP-MS.
Microbiology
Total plate count, yeast and mold, E. coli and Salmonella.

Storage, lots and expiry

Storage and shelf life

Store sodium alginate sealed in a cool, dry place. Viscosity drops over time, faster with heat, so keep stock rotated. Shelf life is set by the supplier's specification, typically as a retest date.

Lots and expiry dates

Viscosity and G/M ratio vary with seaweed species and process, so record both and re-test gel set or viscosity in your system on lot changes. Note the calcium content of your water and other ingredients, which affects how each lot behaves.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Sodium alginate suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking sodium alginate suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

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Frequently asked questions

What forms of sodium alginate can brands buy?

Common forms include viscosity grades, high-G and high-M grades, mesh sizes and pharmaceutical grade. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for sodium alginate include?

Expect assay, viscosity, loss on drying and ash, heavy metals and microbiology, each with its method, specification and result for that lot.

How should sodium alginate be stored?

Store sodium alginate sealed in a cool, dry place. Viscosity drops over time, faster with heat, so keep stock rotated. Shelf life is set by the supplier's specification, typically as a retest date.

What is the regulatory status of sodium alginate?

21 CFR 184.1724 describes sodium alginate as the sodium salt of alginic acid from brown algae and limits its use to listed food categories and levels. 7 CFR 205.605(b) lists alginates as synthetic substances allowed in processed products labeled organic. Health Canada's List of Permitted Emulsifying, Gelling, Stabilizing or Thickening Agents includes sodium alginate.

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