Biochemical tests

• Test for reducing sugars

  Benedict's test

  - Add Benedict's reagent

  - heat

  - observe green/yellow/orange/brick red precipitate
• Test for non-reducing sugar


  - Following a negative Benedict's test

  - boil sample in acid and then neutralise with alkaline

  - add Benedict's reagent and heat

  - observe orange/brick red colour
• Test for starch


  Iodine solution

  - Add iodine solution

  - Stir or shake

  -Positive: Blue black

  -Negative: Orange yellow
• Test for lipids


  - Add ethanol and shake to dissolve

  - then add water

  - white emulsion forms
• Test for protein


  - Add biuret

  - turns purple