Food test

• Test for protein = Biuret test

  Test for Starch = Iodine test

  Test for lipids = Emulsion test

  Test for reducing sugars = Benedict's test

  Test for non-reducing sugars = Benedict's test

  Test for glucose = Test strips
• How to do the Biuret test (proteins)?

  1. Add sodium hydroxide solution
  2. Add copper sulphate solution

  Colour change = blue to purple
• How to do iodine test (starch)?

  1. add iodine in potassium iodine solution

  Colour change from brown-orange to blue-black
• How to do emulsion test (lipids)?

  1. add ethanol
  2. pour solution into water

  solution goes a milky colour
• How to do Benedicts test (reducing sugars)?

  1. add benedicts reagent to a sample and heat in a water bath thats brought to boil

  sample goes from blue to orange to a brick red precipitate
• How to do Benedicts test (non-reducing sugars)?

  1. add dilute hydrochloric acid
  2. put in a water bath brought to boil
  3. neutralise with sodium hydrogen carbonate
  4. do benedicts test for reducing sugars

  sample goes from blue to green to yellow to orange o a brick red precipitate
• How to do test strips (glucose)?

  1. dip test strip in solution

  colour change will occur if glucose is present. Compare to chart of known concentration changes