Test For Starch, Proteins and Fats

Objective 

This topic gives you an overview of; 

  • Contents in Different Food items 
  • Test for starch 
  • Test for proteins 
  • Test for Fats  

What do Different Food Items Contain? 

We know that each dish is usually made up of one or more ingredients, which we get from plants or animals. These ingredients contain some components that are needed by our body. These components are called nutrients. Different food items contain different types of nutrients. Carbohydrates, proteins, fats, vitamins and minerals are important nutrients found in food. 

For carrying out these tests, you will need solutions of iodine, copper sulphate and caustic soda. You will also need a few test tubes and a dropper. 

Test for Starch 

There are many types of carbohydrates. The main carbohydrates found in our food are in the form of starch and sugars. We can easily test if a food item contains starch.  

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

Test for Protein

Proteins are needed for the growth and repair of our body. Foods containing proteins are often called ‘Body Building Foods’. Test if a food item contains protein. 

  1. Take a small quantity of the food items to be tested.
  2. Grind/mash/paste/powder the food item.
  3. Put the food item into a test tube.
  4. Add 10 drops of water and shake the test tube.
  5. Using a dropper add two drops of copper sulphate solution to the test tube.
  6. Add 10 drops of caustic soda solution and shake the test tube.
  7. Observe the colour of the mixture.
  8. Violet colour indicates the presence of proteins in the tested food item. 

Test for Fats 

Fat is a major source of energy and also aids your body in absorbing fat soluble vitamins. You need a minimum of 10 to 20 percent of your overall calories as fat .Test if a food item contains fat. 

  1. Take a small quantity of the food item to be tested.
  2. Wrap the food item in a piece of paper and crush it.
  3. Straighten the paper.
  4. Dry the paper by keeping it in sunlight for a while.
  5. Observe the paper.
  6. An oily patch on the paper indicates the presence of fats in the tested food item. 

Summary 

  • Nutrients are chemical components in food that are required for releasing energy and helps in growth. Carbohydrates and fats mainly provide energy to our body.
  • The major nutrients in our food are carbohydrates, proteins, fats, vitamins and minerals. In addition, food also contains dietary fibres and water.
  • Proteins and minerals are needed for the growth and the maintenance of our body.
  • Starch and sugar are the two kinds of carbohydrates found in food.
  • Carbohydrates and fats mainly provide energy. 

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