HUMAN NUTRITION

Detailed explanation-1: -Amylose present in starch is the reason for change in its colour to blue black. Iodine is not soluble in water so it is dissolved along with potassium iodide that forms a triiodide molecule which enters the helical structure of amylose and changes the colour of starch.

Detailed explanation-2: -Using iodine to test for the presence of starch is a common experiment. A solution of iodine (I2) and potassium iodide (KI) in water has a light orange-brown color. If it is added to a sample that contains starch, such as the bread pictured above, the color changes to a deep blue.

Detailed explanation-3: -Iodine element in the presence of iodide ion will give the characteristic blue-black colour with starch.

Detailed explanation-4: -Iodine solution is used to test the presence of starch in food materials. When iodine solution is added to a food item, it turns into blue-black colour if starch is present. If starch is not present, then the colour will stay orange or yellow.