Question

You have been supplied with a sample of food. How will you perform tests for the presence of starch and proteins in it?

Answer 1

• Test for starch
  

1. Take the food sample.
   
2. If it is a solid crush it using a mortar and pestle.
   
3. Add water and mix it.
   
4. Crush the sample until it turns into a semi-liquid state
   
5. Add brown iodine soln.
   
6. If the liquid on addition turns blue-black there in presence of starch
   

• Test for protien
  

1. Take a small quantity of the food items to be tested.
   
2. Grind/mash 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.