Describe one test each for detecting …

The various food items which we eat daily are usually made up of more than one material called ingredients. The ingredients of food contain components which are needed by our body for proper functioning, called nutrients. The five major nutrients of the food are carbohydrates, proteins, fats, vitamins and minerals. In addition to these nutrients, water and roughage also form a major part of the food. All food items do not contain all major components of food. The presence of a particular component in a food item can be confirmed by performing various tests in the given sample of food.

Test for starch:

1. Take a small quantity of food item to be tested.
2. Add 2 to 3 drops of dilute iodine solution to the food with a dropper.
3. If blue-black colour is produced, then starch is present in the given food.

Test for protein:

1. Take 2 ml of the given food-stuff solution in a test tube.
2. Add a little of dilute sodium hydroxide solution till the mixture clears.
3. Then add 2 to 3 drops of copper sulphate solution and shake well.
4. If a violet colour appears in the solution, then protein is present in the given food-stuff.

Test for fats:

1. Take a small quantity of hard, solid food item and wrap it in a filter paper.
2. Crush the food item carefully by using a small hammer and rub the crushed food on the paper.
3. Remove the crushed food from the paper, and hold the paper towards a source a light.
4. Presence of oily patches on the paper shows the presence of fats in the given food item.