Required Practical 4: Food Tests

• What should you be able to describe by the end of the video?

  How to carry out chemical tests
• What is emphasized about the chemicals used in the tests?

  They are potentially hazardous
• What safety equipment must be worn during the tests?

  Safety goggles
• What is the procedure for preparing a food sample for testing?

  • Grind food sample with distilled water
  • Make a paste
  • Transfer to a beaker and add more distilled water
  • Stir to dissolve chemicals
  • Filter to remove suspended particles
• What are the two main types of carbohydrates mentioned?

  Starch and sugars
• How do you test for starch in a food solution?

  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 color indicates a lot of sugar in the Benedict test?

  Brick red
• 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?

  • Grind food with distilled water
  • Do not filter the solution
  • Transfer to a test tube
  • Add distilled water and ethanol
  • Gently shake the solution
• What indicates the presence of lipids in the test?

  A white cloudy emulsion forms
• Why is it important to avoid naked flames when testing for lipids?

  Ethanol is highly flammable
• What resources can be used for further questions on testing chemicals in foods?

  • Vision workbook
  • Link provided in the video