Carrageenans are composed of linear polysaccharide chains, with sulphate half-esters attached to the sugar unit. They are normally classified according to their structural charac­teristics, and there are at least 15 distinct structures.

Carrageenans are used in the food, textile, and pharmaceutical industries, where they are sought as aids to stabilize emulsions and suspensions. Most carrageenan is currently pro­duced from cell walls of Eucheuma and Kappaphycus spp. Food applications for carrageenans (usually labeled E 407) include canned foods, dessert mousses, salad dressings, bakery fill­ings, ice cream, instant desserts, and pet foods. They are also used as suspension agents and stabilizers in drugs, lotions, and medicinal creams. An illustrative medical application is treatment of bowel problems, such as diarrhea, constipation, or dysentery; they are also used to make internal poultices to control stomach ulcers (Morrissey, Kraan et al., 2001).