Food tests

• Which test is used for sugars?

  Benedict's test
• What is the iodine test used for?

  To test for starch
• What does the Biuret test detect?

  Proteins
• What does the Sudan 3 test check for?

  Lipids
• What additional test is covered for Edexcel students?

  Emulsion test for lipids
• What is the preparation process for food samples before testing?

  • Break food using a mortar and pestle
  • Mix crushed food with distilled water
  • Stir with a glass rod
  • Filter the solution to remove solids
• What are the two types of sugars mentioned?

  Reducing sugars and non-reducing sugars
• What does a blue solution indicate in the Benedict's test?

  No reducing sugars are present
• What color change indicates the presence of reducing sugars in the Benedict's test?

  Green, yellow, or brick red
• How do you perform the iodine test for starch?

  Add iodine solution to the food sample
• What color change indicates the presence of starch in the iodine test?

  From browny orange to blue-black
• What is the procedure for the Biuret test?

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

  Change from blue to pink or purple
• What is the procedure for the Sudan 3 test?

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

  A bright red layer at the top
• What is the Emulsion test for lipids?

  Add ethanol and shake, then add water
• What indicates the presence of lipids in the Emulsion test?

  A cloudy white color
• What resources are available on the Cognito website?

  • Videos on various topics
  • Questions and flashcards
  • Exam-style questions
  • Past papers
  • Progress tracking
• What is the temperature setting for the water bath in the Benedict's test?

  75° C
• Why should you use a test tube holder in the Benedict's test?

  For safety when placing in water bath
• How does the preparation of food samples differ for the Sudan 3 test compared to other tests?

  No need to filter the sample for Sudan 3
• What are the key differences between the tests for sugars, starch, proteins, and lipids?

  • Benedict's test: for reducing sugars, color change indicates presence
  • Iodine test: for starch, color change to blue-black indicates presence
  • Biuret test: for proteins, color change to pink/purple indicates presence
  • Sudan 3 test: for lipids, bright red layer indicates presence