Principles of Biochemistry (2+1)

3.3.4.3 Carrageenan

Carrageenans or carrageenins are a family of linear sulphated polysaccharides extracted from red seaweeds.  The name is derived from a type of seaweed that is abundant along the Irish coastline near the village of Carragheen. Carrageenan consists of alternating 3-linked-β-D-galactopyranose and 4-linked-α-D-galactopyranose units. Carrageenan is a collective term for polysaccharides prepared by alkaline extraction (and modification) from red seaweed (Rhodophycae), mostly of genus Chondrus, Eucheuma, Gigartina and Iridaea. Different seaweeds produce different carrageenans.   

 

Uses: Carrageenans are used mainly for thickening, suspending and gelling. κ- and ι-carrageenans form thermoreversible gels on cooling in the presence of appropriate counterions. κ-Carrageenan stabilizes milk -casein products due to its charge interaction with the casein micelles (~200 nm diameter); their incorporation into the network preventing whey separation. Such complexes are soluble when both have same charge and are held together by counterions or oppositely charged patches.  Carrageenan is also used as a binder in cooked meats, to firm sausages and as a thickener in toothpaste and puddings.