Food tests

Cards (28)

  • What should you be able to describe by the end of the video?
    How to carry out chemical tests
  • Why must safety goggles be worn during the tests?
    Because all chemicals are potentially hazardous
  • What are the key things to learn for the tests?
    • Chemicals used for each food group
    • Positive results of the tests
  • What is the first step in preparing a food sample for testing?
    Grind the food with distilled water
  • What is the purpose of filtering the solution?
    To remove suspended food particles
  • What do carbohydrates include?
    Starch and sugars like glucose
  • 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 is Benedict solution before testing?
    Blue
  • What indicates the presence of sugar in the Benedict test?
    Color change of the solution
  • What does a green color in the Benedict test indicate?
    A small amount of sugar is present
  • 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 color does the Biuret solution turn if protein is present?
    Purple or lilac
  • How do you test for lipids in a food sample?
    Add distilled water and ethanol, then shake
  • What indicates the presence of lipids in the test?
    A white cloudy emulsion forms
  • Why do we not filter the solution when testing for lipids?
    Lipid molecules can stick to filter paper
  • Why is ethanol considered hazardous during the lipid test?
    It is highly flammable
  • What should be avoided when using ethanol in tests?
    • No naked flames should be present
  • Where can you find questions on testing for chemicals in foods?
    In the vision workbook
  • What is the procedure for grinding food samples with distilled water?
    Use a mortar and pestle to make a paste
  • Why is it important to stir the solution after adding distilled water?
    To ensure chemicals dissolve properly
  • What specific volumes of chemicals are used in the tests?
    2 cm cubed for most tests
  • What does the color change in the Benedict test signify?
    It indicates the amount of sugar present
  • What is the distinction between reducing and non-reducing sugars?
    Reducing sugars react in the Benedict test
  • How do you prepare the Biuret test for proteins?
    Add Biuret solution to the food solution
  • Why do we not filter the lipid test solution?
    Lipids can stick to filter paper
  • What safety precautions should be taken when handling ethanol?
    Avoid naked flames around ethanol