color in the presence of iodine. The triiodide ion ion slips into the coil of the starch causing an intense blue-black color. Starch Test: Add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour. A blue-black color results if starch is present.
Also asked, how does iodine react with starch?
Starch consists of two types of molecules, amylose - a soluble starch and amylopectin. When starch is mixed with iodine in water, an intensely blue colored starch/iodine complex is formed. Many of the details of the reaction are still unknown. Apparently, the Iodine gets stuck in the coils of beta amylose molecules.
Why does lugol iodine react with starch?
Lugol's Iodine (IKI) test for the presence of starch: Iodine dissolved in an aqueous solution of potassium iodide - reacts with starch producing a deep blue-black color. This reaction is the result of the formation of polyiodide chains from the reaction of starch and iodine.