Carrageenan

CARRAGEENAN

Synonyms

Carrageenan, Chondrus extract, Irish moss extract.

Biological Source

It is the sulphated polysccharide obtained from the seaweed called Irish moss, the red algae Chondrus crispus Linn., belonging to family Gigartinaceae, class Rhodophyceae.

Geographical Source

France, Denmark, and the United States are the major producers of carrageenan in the world market.

Collection and Preparation

In autumn the algae grown on rocks are collected by means of long rakes from tide water. Carrageenan is extracted from many species of red seaweeds. The process begins with harvesting, followed by drying, cleaning, bagging or bailing. In the factory, the seaweeds are sorted, tested for quality and stored. Before being processed, they are hand-inspected, then washed to remove dirt and marine organisms and then subjected to hot alkaline extraction. When the carrageenan is dissolved, it is clarified through conventional filtration and is then concentrated by membrane ultra-filtration. The carrageenan is precipitated by alcohol or potassium chloride to separate it from soluble impurities. This is followed by drying and grinding to appropriate particle size.

Morphology

Constituents

The constituents of Irish moss are the similar polysaccharides as that of agar. The major constituent is galactans which is known as carrageenan. Carrageenan are classified on the basis of 3,6-anhydro-D-galactose and the position of ester sulphate groups. Three major types of carrageenan are characterized as Kappa, Iota and Lamda-carrageenans. Hydrolysis of the polysaccharides yield galactose, glucose, fructose, arabinose and calcium salt of acid esters of sulphuric acid.

Uses

Carrageenan is used as emulsifying agent, stabilizing agent, solubilizing agent and viscosity builder in food products. Tooth paste, creams, lotions and other cosmetic products are prepared by using carrageenan. In food industry, it is utilized in milk products, ice creams, gels in the concen-tration of 0.5–1%.

Carrageenan is a popular phlogistic agent for inducing inflammation in the rat paw oedema model for the study of antiinflammatory activity.

Substitutes and Adulterants

Irish moss is occasionally mixed with seaweeds like Gigartina stellata Batt. or G. pistillata Lam., which are distinguished stalked cystocarps.