Carrageenans or carrageenins (/ˌkærəˈɡiːnənz/ karr-ə-gee-nənz, from Irish carraigín, “little rock”) are a family of linear sulfated polysaccharides that are extracted from red edible seaweeds. They are widely used in the food industry, for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins. There are three main varieties of carrageenan, which differ in their degree of sulphation. Kappa-carrageenan has one sulphate group per disaccharide, Iota-carrageenan has two, and Lambda-carrageenan has three.
Gelatinous extracts of the Chondrus crispus (Irish moss) seaweed have been used as food additives since approximately the fifteenth century.Carrageenan is a vegetarian and vegan alternative to gelatin in some applications or may be used to replace gelatin in confectionery.
Carrageenans are large, highly flexible molecules that curl forming helical structures. This gives them the ability to form a variety of different gels at room temperature. They are widely used in the food and other industries as thickening and stabilizing agents.
All carrageenans are high-molecular-weight polysaccharides made up of repeating galactose units and 3,6 anhydrogalactose (3,6-AG), both sulfated and nonsulfated. The units are joined by alternating α-1,3 and β-1,4 glycosidic linkages.
There are three main commercial classes of carrageenan:
Kappa forms strong, rigid gels in the presence of potassium ions; it reacts with dairy proteins. It is sourced mainly from Kappaphycus alvarezii.
Iota forms soft gels in the presence of calcium ions. It is produced mainly from Eucheuma denticulatum.
Lambda does not gel, and is used to thicken dairy products.