Food Tests Practicals #16

• What are the food tests covered in the video?

  Benedict's, iodine, buret, and Sudan 3 tests
• What is the purpose of the Benedict's test?

  To test for reducing sugars
• What does the iodine test detect?

  Presence of starch in food
• What does the buret test check for?

  Presence of proteins in food
• What is the Sudan 3 test used for?

  To test for lipids in food
• What is the emulsion test for lipids?

  A test for lipids using ethanol and water
• What is the procedure to prepare a food sample for testing?

  1. Break food using a mortar and pestle
  2. Add crushed food to distilled water in a beaker
  3. Stir until dissolved
  4. Filter using a funnel lined with filter paper
• What temperature should the water bath be set to for the Benedict's test?

  75 degrees Celsius
• What color indicates the presence of reducing sugars in the Benedict's test?

  Green, yellow, or brick red
• What color change occurs in the iodine test if starch is present?

  Changes from browny orange to blue black
• What happens in the buret test if proteins are present?

  Solution changes from blue to pink or purple
• How do you perform the Sudan 3 test?

  Add Sudan 3 to the food sample and shake
• What indicates the presence of lipids in the Sudan 3 test?

  Bright red layer at the top
• What indicates the presence of lipids in the emulsion test?

  Cloudy white color after adding water
• How much food sample is needed for the buret test?

  2 centimeters cubed
• What is the first step in the food testing process?

  Prepare the food sample
• Why should the test tube be pointed away from you in the water bath?

  For safety reasons to avoid burns
• How do the tests for sugars and starch differ in terms of procedure?

  Sugars require Benedict's solution, starch requires iodine
• What is the significance of filtering the food sample before testing?

  To remove solid bits not needed for tests
• What is the role of potassium hydroxide in the buret test for Edexcel students?

  It is added before copper sulfate for specificity
• What color does the buret solution start as?

  Blue
• What happens if no lipid is present in the emulsion test?

  No cloudy white color appears
• How many drops of Sudan 3 solution are added in the Sudan 3 test?

  Three drops
• What is the main difference between reducing and non-reducing sugars?

  Reducing sugars can donate electrons, non-reducing cannot
• How does the presence of reducing sugars affect the color change in the Benedict's test?

  Higher concentration leads to a redder color
• What is the significance of the color change in the iodine test?

  Indicates the presence of starch in the sample
• What is the final appearance of a positive Sudan 3 test?

  Bright red layer on top
• What is the purpose of the glass rod in preparing the food sample?

  To stir the mixture until dissolved
• How do the tests for proteins and lipids differ in terms of reagents used?

  Proteins use buret solution, lipids use Sudan 3
• What is the role of distilled water in preparing the food sample?

  To dissolve the food sample for testing
• What is the color of the iodine solution before testing?

  Browny orange
• What does a blue solution indicate in the buret test?

  No proteins are present in the sample
• How does the procedure for the emulsion test differ from the Sudan 3 test?

  Emulsion test uses ethanol, Sudan 3 uses stain
• Why is it important to shake the test tube gently after adding reagents?

  To ensure proper mixing of the solution
• What is the purpose of the food tests in GCSE biology practicals?

  To identify the presence of nutrients
• What is the significance of using a test tube holder in the water bath?

  To prevent burns while handling hot tubes
• How do the results of the food tests contribute to understanding nutrition?

  They help identify essential nutrients in food