There has been a long tradition of using Irish moss as a food in Ireland where seamen used to gel milk by addition of seaweed. The town of Carragheen was at that time tne centre of this activity, hence the name carrageenan.
Today, carrageenan is extracted from a wide variety of red seaweeds belonging to the class of Rhodophyceae (e.g. Gigartina, Chondrus, Eucheuma, Furcellaria) growing off the coasts of countries all around the world, e.g. the Philippines, Indonesia, Canada, Denmark, Chile, Spain, Japan, and France.

Food grade quality carrageenan is obtained by a multi-step process avoiding any degradation. After careful washing, the seaweed is dissolved in warm alkaline water and filtered.

The product is then recovered by precipitation with isopropyl alcohol and dried at low temperature. An alternative recovery process consists of dewatering a salt gelled solution by pressing or freeze-thawing.

Carrageenan is a high molecular weight polysaccharide consisting of galactose sulfate and anhydrogalactose sulfate units. Total production amounts to 30, 000 tonnes per year, almost all of which is devoted to the food industry.

There are three types of carrageenan, identified by the number and distribution of sulfate groups on the macromolecule which confer to the gel a large variety of properties in term of solubility and texture.

Carrageenan is a permitted food additive in all countries under INS 407 (E407 in the EU).

Several toxicological reviews by expert committees have confirmed its safety and the Joint FAO/WHO Expert Committee on Food Additives has allocated a non specified Acceptable Daily Intake (ADI).

The thickening and gelling properties of carrageenan are strongly depending on the medium (temperature, pH, and the presence of calcium and potassium ions and proteins.)
The main applications are dairy desserts, meat products and water jellies.