RP. Food tests

Question 1

Describe how you would prepare a sample of food to be tested

Answer 1

Grind up food samples using pestle and mortar Mix with water
Filter with funnel and filter paper

Question 2

Describe how you would test for the presence of starch in a sample

Answer 2

Add iodine solution to sample

If starch is present, solution turns from brown to blue-black

Question 3

Describe how you would test for the presence of a reducing sugar in a sample

Answer 3

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

Question 4

Describe how you would test for the presence of protein in a sample

Answer 4

Add Biuret reagent (potassium hydroxide and copper (II) sulphate)

Shake mixture

If protein is present, solution turns from blue to purple

Question 5

Describe how you would test for the presence of lipids in a sample

Answer 5

Add ethanol to the sample

Add water to sample

Shake test tube

White emulsion formed if lipid present