Carrageenans is a sulfur phycocolloid: the aqueous, usually gel- forming, cell-wall polysaccharide mucilage found in red algae (Chondrus crispus and several other species). It is water-extracted from a seaweed called carrageen or Irish moss (east coast of southern Canada, New England, and south to New Jersey). It is a mixture of polysaccharide fractions: (1) The λ fraction is cold-water soluble, contains d-galactose and 35% esterified sulfate, and does not gel. (2) The κ fraction contains d-galactose and 3,6-anhydro-d- galactose (1.4:1 ratio) and 25% esterified sulfate. The κ form does not gel without addition of a solute; the properties of the gel depend on the amount and nature of the added solute. Another species of sea- weed produces 100% κ from North Carolina to the tropics. Carrageenan is a hydrophilic colloid that absorbs water readily and complexes with milk proteins.

Carrageenans are widely used in the food industry, daily-used chemical industry, biochemistry, medical research and the like for their hydrophilic colloid building, gelling, thickening, emulsifying, film forming and stabilizing properties. In the food industry, the addition of carrageenans to the fruit juice makes the fine pulp particles evenly suspended in the juice, greatly slow down the sinking time and improve the taste; the addition of carrageenans in the cocoa malted milk powder makes the cocoa powder evenly dispersed in the milk; adding a small amount of carrageenan to the ice cream makes it taste fine, smoothy and delicious, and not easy to melt during storage; for cakes with patterns and words, the addition of carrageenan makes the patterns well-formed and not easy to deform or be collapsed; the addition of carrageenan to bread increases its water retention capacity, thus delaying hardening and keeping it fresh; carrageenan is also used as a coagulant in jam and fish, meat and other cans and good effects has been shown.

Carrageenan also has certain applications in daily chemicals such as detergents and cosmetics. For example, a carrageenan-added detergent is better than methylcellulose in preventing re-contamination; when used in liquid detergents, it can improve its dispersing and storage properties; in cosmetics, carrageenan can be mixed with glycerin or the like to form an emollient as it is easily absorbed by the skin is adsorbed; in some emulsions and shampoos, it can be used as an emulsifier to make the product soft and smoothy and improve their stabilities.

In the application of photosensitive materials, carrageenan can be used as a sensitizer instead of gelatin, or it can be added as an antistatic agent in gelatin emulsion. It is also used in the pharmaceutical industry as ointment that has no-staining on clothes and is easy to wash; it is also used as pharmaceutical excipients, especially with better effects when used for excipients containing amino-based drugs because it is combined with the acidophobe in the Carrageenan to form a salt which is then slowly released in the body. In addition, it is also used to a certain degree in the leather industry, ceramic industry, textile industry and paper industry. Carrageenan is used as a good immobilized enzyme carrier in the biochemical industry, and many products are produced by using this carrier.

References

Material Safety Data Sheet. 2001. Acetic anhydride. Mallinnckrodt Baker, Inc., New Jersey (updated 2007).
U.S. Environmental Protection Agency. 1987. Health assessment document for acetaldehyde.
EPA/600/8-86-015A. Research Triangle Park, NC: Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of
Research and Development.