Food

• Preparing food sample for testing

  1. Break up food using mortar and pestle

  2. Put crushed food in beaker with distilled water

  3. Stir with glass rod until some dissolves

  4. Filter solution through funnel with filter paper
• Sugars

  Small units that all carbohydrates are made of
• Types of sugars

  • Reducing sugars
  • Non-reducing sugars
• Benedict's test only tests for reducing sugars
• Benedict's test for reducing sugars

  1. Transfer 5cm3 of food sample to test tube

  2. Prepare 75°C water bath

  3. Add 10 drops of Benedict solution to test tube

  4. Place test tube in water bath for 5 minutes
• Starch


  A type of carbohydrate that is a larger and more complex molecule than sugars
• Iodine test for starch

  1. Add 5cm3 of food sample to test tube

  2. Add a few drops of iodine solution
• Buret test


  Test for proteins
• Buret test for proteins

  1. Add 2cm3 of food sample to test tube

  2. Add 2cm3 of Buret solution

  3. Shake gently
• For Edexcel, add potassium hydroxide followed by copper sulfate instead of just Buret solution
• Sudan 3 test

  Test for lipids
• Sudan 3 test for lipids

  1. Add 5cm3 of food sample to test tube

  2. Add 3 drops of Sudan 3 stain solution

  3. Shake gently
• Emulsion test

  Alternative test for lipids for Edexcel
• Emulsion test for lipids

  1. Add 2cm3 of ethanol to food sample

  2. Shake vigorously

  3. Add equal volume of distilled water