GKM+activity+1


 * 1) Think about the chemical structure of carrageenan and agar - what do they have in common?
 * 2) What are the differences between kappa, iota and lambda carrageenan? Why?

Answer: 1. Carrageenans have high molecular weight polysaccharides which is made up of 3,6 anhydrogalactose monomers, both sulfated and nonsulfated. The unit are joined by alrering alpha1-3 and beta 1-4 glycosidic linkages. Whereaas a agar is made up of agarose and agarpectin. agar is linear polymer with agarbinose monomer. Agarbinose is consisted by D-galactose and 3,6-anyhro-Lgalactopyranose. so, agar structure is differ from the carrageenans in such a way that carrageenans having a  3,6-anhydrogalactose for both sulfated and nonsulfated but agar having alternate of D-galactose and 3,6 anhyro-L-galactose and lack of sulfate group.

2. Kappa carrageenans is strong, rigid gels and will gels with potassium ions, react with dairy proteins. iota carrageenans is a soft gel that gel with calcium but Lambda carrageenans doesnt gel, so it is used to thicken dairy products. The primary differences which influence the properties of kappa, iota and lambda carrageenan are the number and position of the ester sulfate groups on the repeating galactose units. Higher levels of ester sulfate lower the solubility temperature of the carrageenan and produce lower strength gels, or contribute to gel inhibition (lambda carrageenan).