How can you test for presence of starch in Food items?

Answer 1

To identify the presence of starch in Food items;

Iodine Test: (specific for starch)

Principle:

When boiled with water starch molecules form dispersion surfaces having affinity for Iodine molecules. When added, iodine molecules get adsorbed on starch grains producing intense blue colour.

Reagent: 1) Iodine solution(2 grams of 12 dissolved in 6% KI)

2) 1% starch solution (Dissolve 1 gram of starch in 100mL of boiling water).

Procedure:

Take 2mL of food extract or 2mL of starch solution in a test tube and add a few drops of iodine solution to it. Note the change in colour.

Result:

If a blue black develops then starch is present. Colour due to adsorption.