Food tests

  • Test for starch - Add Iodine & it goes blue black
  • Test for lipids- Emulsion test
    • Process
    • Dissolve lipid in alcohol
    • Add water
    • If emulsion forms lipids present
  • Test for Protein - Biuret test
    • Process
    • Dissolve sample in water
    • Add Biuret solution, if protein present it turns from blue to lilac
  • Test for reducing sugars - Benedicts test
    • Dissolve sample
    • Add equal volume of benedicts solution
    • Heat at > 60C for 5 Mins
    • If reducing sugar present then it turns from blue to green/orange/brick red
  • Test for a non reducing sugar - Basically just a longer Benedict's a standard Benedict’s test must be performed first and come back negative
    • Then after Benedict’s test with a new sample;
    • Dissolve sample in water
    • Add equal volume of dilute HCl
      • This hydrolyzes the bonds between dipeptides artificially
    • Heat at >60C for 5 mins
    • Neutralize it with Sodium bicarbonate until it stop fizzing
    • Add equal volume of benedicts solution
    • Heat at > 60C for 5 Mins
    • If positive then it turns from blue to green/orange/brick red