GCSE food tests Flashcards
What color change indicates the presence of starch in the iodine test?
The solution turns from brown to blue-black.
List the equipment needed for the iodine test for starch.
- Food sample
- Test tube
- Iodine solution (0.01 mol/dm3)
- Pipettes
What is the method for the iodine test for starch?
Put some food sample into a test tube and add a few drops of iodine solution.
What indicates the presence of reducing sugars in the Benedict’s test?
A brick red precipitate is formed.
What color does the solution remain if reducing sugar is absent in the Benedict’s test?
The solution remains blue.
List the equipment needed for the Benedict’s test for reducing sugars.
- Food sample
- Test tube
- Benedict’s solution
- Hot water bath
- Thermometer
- Pipettes
What is the method for the Benedict’s test for reducing sugars?
Add an equal volume of Benedict’s solution to the food sample and place in a hot water bath.
What color change indicates the presence of protein in the Biuret test?
The solution turns from blue to purple.
List the equipment needed for the Biuret test for protein.
- Test tube
- 10cm3 measuring cylinder
- Biuret solution
What is the method for the Biuret test for protein?
Add a few drops of Biuret’s reagent to the food sample and shake the solution.
What indicates the presence of lipids in the emulsion test?
A white emulsion is formed on the surface of the mixture.
List the equipment needed for the lipid test.
- Food sample
- Test tube
- Ethanol
- Distilled water
What is the method for the lipid test?
Add ethanol to the food sample, then pour into a test tube of distilled water.
What are some sources of error in the food tests?
Colour change may be subtle and difficult to judge if the concentration is low.
What safety precautions should be taken when performing the Benedict’s test?
Tie hair back and wear safety goggles.
What should you do if Biuret solution comes into contact with skin?
Wash immediately.
True or False: Ethanol solution should be kept away from flames because it is highly flammable.
True
