Carrageenan

Carrageenans or carrageenins (/ˌkærəˈɡiːnɪns/ KAH-rə-GHEE-nihns; from Irish carraigín 'little rock') are a family of natural linear sulfated polysaccharides. They are extracted from red edible seaweeds. Carrageenans 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. Carrageenans have emerged as a promising candidate in tissue engineering and regenerative medicine applications as they resemble animal glycosaminoglycans (GAGs). They are used for tissue engineering, wound coverage, and drug delivery.

Carrageenans contain 15–40% ester-sulfate content, which makes them anionic polysaccharides. They can be mainly categorized into three classes based on their sulfate content. Kappa-carrageenan has one sulfate group per disaccharide, iota-carrageenan has two, and lambda-carrageenan has three.

A common seaweed used for manufacturing the hydrophilic colloids to produce carrageenan is Chondrus crispus (Irish moss), which is a dark red, parsley-like alga that grows attached to rocks. Gelatinous extracts of C. crispus have been used as food additives since approximately the fifteenth century. Carrageenan is a vegetarian and vegan alternative to gelatin in some applications, and is used to replace gelatin in confectionery and other food.

The first industrial commercial cultivation of Eucheuma and Kappaphycus spp. for carrageenan was developed in the Philippines. The global top producers of carrageenan are the Philippines and Indonesia. Carrageenan, along with agar, is used to produce traditional jelly desserts in the Philippines called gulaman.

No clinical evidence establishes carrageenan as an unsafe food ingredient, mainly because its fate after digestion is inadequately determined.

Carrageenans are large, highly flexible molecules that form curling 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 and mainly made up of alternating 3-linked β-D-galactopyranose (G-units) and 4-linked α-D-galactopyranose (D-units) or 4-linked 3,6-anhydro-α-D-galactopyranose (DA-units), forming the disaccharide repeating unit of carrageenans.

There are three main commercial classes of carrageenan: