Sodium alginate An algae-extracted gelling agent, sodium alginate is used in molecular gastronomy in association with calcium salts for the basic spherification and reverse-spherification processes, whether to make small caviar-like pearls or large ravioles.
The properties of sodium alginate were studied for the first time in 1881 by English chemist ECC Stanford. He had at the time extracted a viscous liquid from brown seaweed of the Laminaria species, with an alkaline solution. He called this product "Algin", a term still commonly used to describe sodium alginate.
Sodium alginate is therefore a salt extracted from the viscous liquid from the cell wall of brown algae. Its natural function is to increase the flexibility of the algae. Thus, algae developing in troubled waters generally have larger alginate content than those growing in calm waters.
Although all brown algae can be a source of alginate, variations in their chemical structure influence the properties of the final product. Different species are therefore harvested according to the purposes for which they are intended and the two most popular are the macrocystis pyrifera of California and the ascophyllum nodosum, grown in the North Atlantic.
The uses of sodium alginate take advantage of two special properties it has. On the one hand, once dissolved in an aqueous solution, sodium alginate has the property of thickening the preparation and increasing the viscosity. On the other hand, when brought into contact with a calcium solution, it forms a gel. This gelling occurs through a cold process, as opposed to the formation of agar-agar gels.
Approximately 50% of the world production of alginate is used by the textile industry where the additive is used as an ink thickener in the printing process.
For its part, the food processing industry uses 30%. The thickening properties of alginate are used for example in sauces, syrups and some products containing milk. It is also used as a stabilizer and anti-settling agent in ice cream and milkshakes, as well as acting as a stabilizer and emulsifier in some salad dressings.
The rest of the production is mainly directed towards the pharmaceutical and pulp and paper industries.