food tests

• Food tests


  1. Prepare food sample

  2. Crush food with mortar and pestle

  3. Dissolve in distilled water

  4. Filter solution
• Sugars


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


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

  1. Prepare food sample

  2. Transfer 5cm3 to test tube

  3. Heat in 75°C water bath

  4. Add Benedict's solution

  5. Observe colour change
• Starch


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

  1. Add 5cm3 food sample

  2. Add iodine solution

  3. Observe colour change
• Biuret test for proteins

  1. Add 2cm3 food sample

  2. Add 2cm3 Biuret solution

  3. Observe colour change
• Edexcel lipid test (emulsion test)

  1. Add 2cm3 food sample

  2. Add 2cm3 ethanol, shake

  3. Add equal volume distilled water

  4. Observe cloudiness
• Sudan 3 test for lipids

  1. Add 5cm3 food sample

  2. Add 3 drops Sudan 3 stain

  3. Observe red layer
• These are the food tests needed for GCSE biology practicals