Required practical food tests

• Aim of the practical

  Describe how to carry out chemical tests for carbohydrates, proteins and lipids.
• Method for preparing food sample summarised

  1) Mortar and pestle

  2) Beaker and distilled water

  3) Filter the solution
• 1) Mortar and pestle

  Take the food sample and grind with distilled water using a mortar and pestle to make a paste.
• 2) Beaker and distilled water

  Transfer the paste to beaker and add more distilled water. Stir so chemicals in the food dissolve in the water.
• 3) Filter the solution


  Filter the solution to remove suspended food particles.
• What is the test for starch?


  If starch is present, iodine solution will turn blue-black.
• What is the test for reducing sugars?


  If reducing sugars are present, the Benedict's will turn from blue to green, yellow or red.
• What is the test for protein?


  If proteins are present, the biuret solution turns from blue to purple.
• What is the test for lipids/fats?


  If lipids are present, a white cloudy emulsion forms.