biochemical tests

• test for starch

  • add iodine
  • colour change from orange - blue/black
• test for reducing sugars

  • add benedicts reagent
  • heat
  • colour change blue - brick red
• test for non-reducing sugars (sucrose)

  • first test if its not a reducing sugar using benedicts reagent
  • add an acid and boil for two minutes ( acid hydrolysis ) sucrose breaks down into glucoseand fructose
  • let it cool and add an alkali to neutralise
  • add benedicts reagent and heat
  • colour change blue - brick red
• test for proteins

  • add biuret
  • colour change blue - purple
• test for lipids

  • dissolve sample in ethanol
  • add distilled water
  • white emulsion