Starch is found in cereal grains, roots, tubers, potatoes, etc. It is a polymer of α-D-glucose and consists of two components, amylose and amylopectin.
Amylose is water soluble component forms blue coloured complex with iodine. It constitutes about 20 % of starch.
Amylose contains 200 to 1000 α-D-glucose units linked together by glycosidic linkage between C-l of one unit and C-4 of another unit. i.e. α-1, 4 glycosidic linkages.
Amylopectin is insoluble in water and constitutes about 80 % starch which forms blue-violet coloured complex with iodine.
It is a branched chain polymer.
In amylopectin,
α-D-glucose molecules are linked together by glycosidic linkage between C1 – of one unit and C-4 of another unit to form long chain and branching αcurs by glycosidic linkage between C-1 and C-6 glycosidic linkage.
