Experiment 3: Iodine Test for Carbohydrates - PDF

EXPERIMENT#3 OBJECT: To perform Iodine test for identification of carbohydrates REQUIREMENTS: Test tubes with holders, beaker, sample of carbohydrate, Iodine solution, PRINCIPLE The iodine test is based on the absorptive properties possessed by large polysaccharide molecules. The glucose chains...

EXPERIMENT#3 OBJECT: To perform Iodine test for identification of carbohydrates REQUIREMENTS: Test tubes with holders, beaker, sample of carbohydrate, Iodine solution, PRINCIPLE The iodine test is based on the absorptive properties possessed by large polysaccharide molecules. The glucose chains in most of the polysaccharides are organized to form helices. The space between the turns of the helix can hold small iodine molecules. This is seen with amylase chains found in starch. Glycogen and amylopectin can also absorb these iodine molecules on their surface. The absorptive property of polysaccharides decreases upon heating. Blue or red-colored iodine complexes are formed in this test having ill-defined chemical nature. PROCEDURE:  Take the sample solution to be tested in a clean, dried test tube.  Add 2-3 drops of iodine solution.  Observe the change in color. OBSERVATIONS Appearance of blue colour solution. RESULT: The test confirms the presence of Starch in the given sample