Carrageenan - Production

Production

Although carrageenans were introduced on an industrial scale in the 1930s, they were first used in China around 600 B.C. (where Gigartina was used) and in Ireland around 400 A.D. Carrageen gelatin can be prepared at home using the traditional recipe found in Diderot's encyclopedie and used for centuries. 5oz rinsed Irish moss is cooked with 8 quarts of water for 10 minutes, stirred as it boils. Hard water should be mixed with 1/2 oz of borax. Two quarts of cold water are rapidly added to the hot brew, and after the mixture has cooled it is strained through a cloth. It is then cooled for 24 hours and becomes gelatinous.

The largest producer of industrial carrageenan currently is the Philippines, where cultivated seaweed produces about 80% of the world supply. The most commonly used sources are E. cottonii (Kappaphycus alvarezii, K.striatum) and E. spinosum (Eucheuma denticulatum), which together provide about three-quarters of the world production. These grow from the sea surface to a depth of about 2 metres. The seaweed is normally grown on nylon lines strung between bamboo floats, and it is harvested after three months or so, when each plant weighs approximately 1 kg.

The E. cottonii variety has been reclassified as Kappaphycus cottonii by Maxwell Doty (1988), thereby introducing the genus Kappaphycus, on the basis of the phycocolloids produced (namely kappa carrageenan).

After harvest, the seaweed is dried, baled, and sent to the carrageenan manufacturer. There the seaweed is ground, sifted to remove impurities such as sand, and washed thoroughly. After treatment with hot alkali solution (e.g., 5–8% potassium hydroxide), the cellulose is removed from the carrageenan by centrifugation and filtration. The resulting carrageenan solution is then concentrated by evaporation. It is dried and ground to specification.

There are three types of industrial processing: