Food test practicals

• 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 for 5 minutes

  4. Add Benedict's solution
• Benedict's test


  • Tests for reducing sugars
  • Solution turns green, yellow or brick red if reducing sugars present
• Starch


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


  1. Take 5cm3 of food sample

  2. Add iodine solution

  3. Solution turns blue-black if starch present
• Buret test


  Test for proteins
• Buret test for proteins


  1. Take 2cm3 of food sample

  2. Add 2cm3 of Buret solution

  3. Solution turns pink or purple if proteins present
• Lipids

  Tested using Sudan 3 and emulsion tests
• BENEDICTS


  Test for sugars

  colour: blue - brick red
• Biurets


  Test for protein

  Colour: pale blue - lilac
• Ethanol + water


  Test for lipids

  Colour: colourless - cloudy white
• Iodine


  Test for starch

  Colour: Brown -blue/black