Food Tests

• Describe now you would prepare a sample of food to be tested

  Grind up food samples using pestle and mortar, mix with water, filter with funnel and filter paper.
• How would you test for the presence of starch in a sample?

  Add iodine solution to sample, if starch is present, solution turns from brown to blue-black.
• How would you 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.
• How would you test for the presence of protein in a sample

  Add Biuret reagent (potassium hydroxide and copper (II) sulphate), shake mixture, if protein is present turns from blue to purple.
• How would you test for the presence of lipids in a sample?

  Add ethanol to the sample, add water to the sample, shake test tube, white emulsion formed if lipid is present.