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