Question

4. Starch forms a dark blue complex when treated with iodine. Partially hydrolyzed forms (still a polymer) of starch (erythrodextrin and glycogen) give a red complex. These colored complexes become colorless when heated but the color comes back again upon cooling. A single drop of Iz in KI solution is enough to give an unmistakable test on a solution or a solid. Explain how the image below relates to this experiment Amylosehelice with the glucose-monomerunit: -OH O 0. но-

Answer 1

There are two components in starch-one is amylose that gives blue color with iodine and other one is amylopectine that gives red in iodine. when starch is hydrolyzed (with acid or enzyme hydrolysis) then the blue color is disappeared. the rate of the disappearance of color indicates the enzyme activity.

So the above image has shown the reaction between iodine and amylose- Since iodine only reacts with starch and gives blue color and color is disappear when starch is hydrolyzed. And iodine not react with monosaccharides, that's iodine test is used to differentiate between monosaccharides and polysaccharides. does not react with glucose unit so