ACTIVITY+1...

 Agar and Carrageenan __Think about the chemical structure of carrageenan and agar - what do they have in common?__

** Agar = ** Ø Extracted from seaweed and is used in many foods as a gelling agent. Ø Agar is a polymer of agarobiose, a disaccharide composed of D-galactose and 3,6-anhydro-L-galactose. Ø Highly refined agar is used as a medium for culturing bacteria, cellular tissues, and for DNA fingerprinting. Ø ** used as ** = -An ingredient in desserts in Japan and other Asian countries. The gels produced with agar have a crispier texture than the desserts made with animal gelatin.

** Carrageenan = ** Ø A generic term for several polysaccharides also extracted from seaweed. Ø Carrageenan compounds differ from agar in that they have sulfate groups (**-OSO3**-) in place of some hydroxyl groups. - carrageenan structure is composed of linear galactan polysaccharides that have a sulfate content of 15%-40%. Ø ** used as ** = -Thickening, suspending, and gelling food products. __What are the differences between kappa, iota and lambda carrageenan? Why?__ There are 3 types of carrageenan : 3,6-anhydrous-D-Galactose || D-Galactose-4-Sulphate linked with 3,6-Galactose-2-Sulphate || D-Galactose-2-Sulphate and D-Galactose-2,6-Disulphate ||
 * 1) Kappa
 * 2) Lambda
 * 3) Iota
 * **Types of carrageenan** || Kappa || Lambda || Iota ||
 * **Repeating Unit** || D-Galactose-4-Sulphate linked with
 * **Sulphate content** || ~25% || ~32% || ~35% ||
 * 1) ====== //Kappa-// carrageenan is mostly the alternating polymer of D -galactose-4-sulfate and 3,6-anhydro- D -galactose. //Iota// -carrageenan is similar,except that the 3,6-anhydrogalactose is sulfated at carbon 2. ======
 * 2) ======Between //kappa// -carrageenan and //iota// -carrageenan there is a continuum of intermediate compositions differing in degree of sulfation at carbon 2. ======
 * 3) ======In //lambda// -carrageenan,the alternating monomeric units are mostly D -galactose-2-sulfate (1,3-linked)and D -galactose-2,6-disulfate (1,4-linked). ======