Detection of Starch in Food Samples

Materials Required

Real Lab Procedure

  • Place a potato on a tile.
  • Grind or chop the potato into small pieces, using a knife.
  • Using a spatula transfer these pieces of potato into a beaker.
  • Pour some distilled water into the beaker.
  • Place the beaker containing the mixture over a hot plate.
  • Heat the mixture for 5 minutes while continuously stirring it with a glass rod.
  • Take another beaker and cover its mouth with a muslin cloth.
  • Secure the muslin cloth around the mouth of the beaker by tying it with a thread.
  • Filter the solution through this beaker.
  • Now take a clean test tube and pour some of the filtrate into it.
  • Take a few drops of iodine solution using a dropper.
  • Add a couple of these drops into the test solution.

Simulator Procedure (as performed through the Online Labs)

  • You can select the type of test from the ‘Select type of the test’ drop down list.
  • To select a particular food sample, click on the corresponding icon.
  • Click and drag the dropper towards the food sample to pour a few drops of Iodine solution into the test sample.
  • Then drag the dropper back to place it in the Iodine bottle.
  • Based on your observation, you can indicate the presence of starch in the selected sample by clicking on the 'Yes' or 'No' radio button.
  • You can redo the experiment by clicking on the ‘Reset’ button.

Note: If the solution turns to blue-black colour it indicates the presence of starch in the solution.

Observation

The test solution turns blue-black in colour.

Inference

Iodine reacts with starch to form starch/iodine complex which has a blue-black colour. The appearance of blue-black colour confirms the presence of starch in the given food sample.

Precautions

  • While using iodine solution, be careful, as it is toxic if swallowed or inhaled.
  • While heating, care should be taken that the solution does not splash on your face.

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