Alginic Acid
What it does
Thickener/gelling agent.
How it's made
Extracted from brown seaweed.
Alginic acid is a natural thickening and gelling agent extracted from brown seaweeds. It is used to thicken and stabilise foods and to form gels, and it is the parent substance of the widely used alginate salts. In the seaweed it forms part of the cell walls, giving the plant its flexible strength.
It is obtained by harvesting brown seaweeds (kelps such as Laminaria and Macrocystis), which are treated with alkali to dissolve out the alginate as a soluble sodium salt. This solution is filtered to remove seaweed debris, and then acid is added to precipitate alginic acid, which is collected.
The alginic acid is washed, purified and dried into a powder. Because the free acid is only sparingly soluble, it is often converted into its more soluble salts (like sodium alginate) for many uses; as a seaweed extract it is a plant-based, vegetarian and vegan thickener.
Possible reactions
Generally safe.