Required Practical: Food Tests

• What is the focus of the required practical mentioned?

  The chemical tests for carbohydrates, proteins, and lipids
• What is the procedure for preparing a food sample for testing?

  1. Grind food sample with distilled water using a mortar and pestle.
  2. Transfer paste to a beaker and add more distilled water.
  3. Stir to dissolve chemicals and food.
  4. Filter to remove suspended food particles.
• How do you test for starch in a food sample?

  Add iodine solution to the food solution
• What color does iodine turn if starch is present?

  Blue-black
• What color does iodine remain if no starch is present?

  Orange
• How do you test for sugars like glucose?

  Add Benedict solution and heat in water
• What color indicates a small amount of sugar in the Benedict test?

  Green
• What does a brick red color in the Benedict test indicate?

  A lot of sugar is present
• What type of sugars does the Benedict test work for?

  Reducing sugars
• What is the test for proteins?

  Add Biuret solution to the food solution
• What color change indicates the presence of protein in the Biuret test?

  Blue to purple or lilac
• What is the procedure for testing lipids?

  1. Grind food with distilled water using a mortar and pestle.
  2. Transfer to a test tube without filtering.
  3. Add distilled water and ethanol.
  4. Shake gently to observe for emulsion.
• What indicates the presence of lipids in the lipid test?

  A white cloudy emulsion forms
• Why do we not filter the solution when testing for lipids?

  Lipid molecules can stick to filter paper
• What is the hazard associated with ethanol in the lipid test?

  Ethanol is highly flammable
• What should be avoided when using ethanol in the lipid test?

  • No naked flames should be present
• What is the approximate heating duration for the Benedict test?

  Around 5 minutes
• What is the color of the Benedict solution before testing?

  Blue
• What does the color change in the Benedict test indicate?

  The amount of sugar present