food tests

• Carbohydrates :


  • a liquid sample is added to a test tube
  • add a drop of iodine to sample
  • if the sample turns blue/black then starch is present
• Sugars:


  • add a liquid sample to test tube
  • add in benedicts solution and place sample in a beaker of boiling water
  • if sample turns red/orange then sugar is present
• Protein:


  • add a liquid sample to test tube
  • add 2cm3 of biuret solution
  • if sample turns purple then protein is present
• lipids:


  • add liquid sample to test tube
  • add a drop or 2 of ethanol to sample
  • if a cloudy white layer appears lipids are present