Food Tests RPA

• • Aim: To use qualitative reagents to test for a range of carbohydrates, lipids and proteins. To include: Benedict’s test for sugars, Iodine test for starch, the emulsion test for lipids and the Biuret reagent for protein
• • You will:
  • Use qualitative reagents to test for the presence of key biological molecules in a range of foods
  • Safely use appropriate heating devices and techniques including the use of a Bunsen burden and a water bath
• • A qualitative food test indicates if a substance is present or absent in a sample (although it doesn’t tell you how much is present)
  • Observations are essential in this practical; you are looking for colour changes in particular which can indicate if a substance is present or absent:
• Test for starch:

  • Use iodine solution, its colour is orange-brown
  • The change is blue-black
• Test for sugar:

  • use Benedict's solution, its a light blue colour
  • The colour change is green- brick red
• Test for lipids:

  • Use ethanol, its a colourless reagent
  • The colour change is a cloudy-emulsion
• Test for protein;
• Tests for protein;

  • Use biuret solution, it is a blue colour
  • The colour change is to lilac-purple