Yapa Wijeratne

M/07/189

Polysaccharides Starch-homopolymer of glucose forming an α-glucosidic chain called Glucosan/Glycan 1) Amylose-nonbranching, helical 2) Amylopectin-branched chains -24-30 residues α 1-4 linkages-chain α 1-6 linkages-branch point The extent to which starch in foods is hydrolyzed by Amylase 1) Its shape 2) The degree of crystallization or hydration (the result of cooking) 3) Whether it is enclosed in intact(& indigestible)plant cell walls. Glycemic index 1) Glycogen-animal starch

i) Highly branched than amylopectin.(12-14 glucopyranose residues) 2) Inulin

i) Polysaccharide of fructose. (Fructosan) ii) Readily soluble in water. iii) Used to determine the glomerular filtration rate. iv) Not hydrolyzed by intestinal enzymes. v) Found in tubers & roots of dahlias, artichokes & dandelions.

3) Dextrins – Intermediates in the hydrolysis of starch. 4) Cellulose

i) Chief constituent of plant cell walls. ii) Insoluble. iii) ß-D-Glucopyranose ß 1-4 linkages iv) long ,straight chains strengthened by cross linking H-bonds.

5) Chitin i) Structural polysaccharide in exoskeleton of crustaceans & insects. ii) In mushrooms. iii) Has N.

6) Glycosaminoglycans (mucopolysaccharides) i) Complex carbohydrates containing Amino sugars & Uronic acids.

7) Proteoglycan i) Compounds that chains of complex carbohydrates attached to protein molecules. ii) Provide the ground or packing substances of connective tissue. iii) Hold large quantities of H2O & occupy space-cushioning or lubricating other structures. iv) Because of large number of –OH groups & (-) charge on the molecule, which by repulsion,

keep the carbohydrates chains apart. (a) Hyaluronic acid (b) Condroitin sulphate (c) Heparin

8) Glycoproteins(mucoproteins) i) Proteins containing branched or unbranched oligosaccharide chains. ii) In Cell membranes. iii) e.g. Serum Albumin.