Carrageenan is a kind of lyophilic colloid distilled from some red algae plants. Its chemical structure is calcium, potassium, sodium and ammonium salt of polysaccharide salfate composed of galactose and dehydrated galactose. According to the different salfate combination, carrageenan can be divided into three types: Kappa, Iota and Lambda types.

The use of carrageenan stems from hundreds of years ago. In coastal area of South Ireland, there was a kind of alga, commonly called as Irish Moss, which is named as Chondrus crispus now. Local residents often picked and put it into milk, added some cane sugar and drank after it solidified. In early 18th century, the Irish made this alga into powder and introduced it to America. Then it began to be produced commercially by a company and was sold as sea moss farina. It was widely used in milk and other food. In 19th century, the American began to extract carrageenan in factories. In 1840s, carrageenan industry began to develop in America.