Required practical 4 : Food tests

    Cards (7)

    • Step 1 : Take the food sample and grind with distilled water using a mortar and pestle to make a paste
    • Step 2: transfer the paste to a beaker and add more distilled water. Stir so the chemicals in the food dissolve in the water
    • Step 3 : filter the solution to remove suspended food particles
    • Testing for starch :
      1. place 2cm^3 of food solution into a test tube
      2. Add a few drops of iodine solution (orange)
      3. ✅if starch is present then the solution will turn blue-black
      4. ❌no starch present the solution will stay orange
    • Testing for sugars
      1. Place 2cm^3 of food solution into a test tube
      2. Add 10 drops of Benedict’s solution (blue)
      3. Place the test tube in a beaker and half-fill the beaker with hot water from a kettle, leave for 5 minutes
      4. ✅if sugars are present the solution will turn brick red/yellow/green
      5. ❌no sugars present solution will remain blue
    • Testing for proteins
      • Place 2cm^3 of food solution
      • Add 2cm^3 of biuret solution
      • ✅if protein is present the solution will turn purple
      • ❌no protein solution will remain blue
    • Testing for lipids :
      • Add 2cm^3 of food solution (unfiltered because lipids molecules stick to filter paper)
      • Add 3 drops of Sudan ||| solution
      • ✅if lipids are present a red stained oil layer appears in the solution
      • ❌no lipids the solution will remain red