PAG 2: food tests

Cards (5)

  • describe how you would prepare a sample of food to be tested
    1. grind up food samples using pestle and mortar
    2. mix with water
    3. filter with funnel and filter paper
  • describe how you would test for the presence of starch in a sample
    • add iodine solution to a sample
    • if starch is present, solution turns from brown to blue-black
  • describe how you would test for the presence of reducing sugar in a sample
    • add benedict's reagent to sample
    • boil test tube in a hot water bath
    • if reducing sugar is present, a brick red precipitate forms. if not, the solution remains blue
  • describe how you would test for the presence of starch in a sample
    • add biuret reagent (potassium hydroxide and copper (II) sulphate)
    • shake mixture
    • if protein is present, solution turns from blue to purple
  • describe how you would test for the presence of lipids in a sample
    • add ethanol to sample
    • add water to sample
    • shake test tube
    • white emulsion formed if lipid present