What is alginate?

Alginate is the brown algae's equivalent to the cellulose found in land plants: an extremely long sugar molecule ­ a polysaccharide ­ which provides both flexibility and strength to the algae. Alginate has the ability to thicken, to emulsify, to stabilize and to form jells, and it has traditionally been used in hundreds of different products and processes, such as paper surfaces, dyes for textile printing, nutrients, welding rods, latex paint.

It consists of anything from around 50 units to 200 000 units of the following two types of sugar molecules: mannuronic acid (M) and guluronic acid (G). About ten to twenty million tonnes of seaweeds, mainly brown algae, grow along the Norwegian coast. The best deposits are found along the Trøndelag coast.

Every year Norwegian industry harvests about 200 000 tonnes of kelp and knotted wrack along the coast from Rogaland up to Trøndelag. There are small, but important, differences between the alginate from knotted wrack and that from the stems and leaves of the kelp. These chemical differences make it possible to create a whole range of alginates, each with different practical properties.

Every year Norwegian industry produces 6 000 tonnes of pure alginate. 99 per cent of this is exported, and this constitutes one quarter of total world production. At present the annual export value is about 400 million Norwegian kroner.