Test For Starch, Proteins and Fats

Summary

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Nutrients are nourishing components of food that are required by our body. They release energy and help in body growth. Nutrients found in our food are carbohydrates, proteins, fats, vitamins, minerals and water. Different types of food contain two or more nutrients in combination. Carbohydrates are instant source of energy. Fats are high energy reserves. They are stored for future use. Proteins are the building blocks of our body which mainly help in growth. Two major forms of carbohydrates are starch and sugar.

The following steps are performed to test the presence of starch in a food item

  • Take small quantity of the food item to be tested.
  • Put 2-3 drops of iodine solution on it.
  • Observe the colour of the food item.
  • Blue-black colour indicates the presence of starch in the tested food item.

The following steps are performed to test the presence of protein in a food item

  • Take a small quantity of the food item to be tested.
  • Grind/mash/paste/powder the food item.
  • Put the food item into a test tube.
  • Add 10 drops of water to the test tube.
  • Add two drops of copper sulphate solution to the test tube.
  • Add 10 drops of caustic soda solution and shake the test tube.
  • Observe the colour of the mixture.
  • Violet colour indicates the presence of proteins in the tested food item.

The following steps are performed to test the presence of fat in a food item

  • Take a small quantity of the food item to be tested.
  • Wrap the food item in a small piece of paper.
  • Crush the food item wrapped in the paper.
  • Straighten the paper.
  • Dry the paper by keeping it in sunlight for a while.
  • Observe the paper.
  • An oily patch on the paper indicates the presence of fat in the tested food item.

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