- Different food items contain different types of nutrients.
- Nutrients are chemical components in food that are required for releasing energy and helps in growth.
- Carbohydrates, proteins, fats, vitamins and minerals are important nutrients found in food.
- Carbohydrates and fats mainly provide energy.
- Proteins mainly help in growth.
- Starch and sugar are the two kinds of carbohydrates found in food.
- To test the presence of starch in a food item, you need to:
- Take small quantity of the food items 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.
- To test for the presence of proteins in a food items, you need to:
- Take a small quantity of the food items 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.
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- To test for the presence of fats in a food item, you need to:
- 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 fats in the tested food item.
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