Testing for Protein - The Biuret Test

Testing for Protein - The Biuret Test

Aim: to test if a sample of food contains protein

Method:
1. Place about 2 ml of the sample into a test tube and add 5 drops of sodium hydroxide.
2. Add 5 drops of copper sulphate.
3. shake the test tube.

Results: If the solution remains blue, then no protein is present. If the solution changes to a purple colour then protein is present in the sample

Conclusion: if food sample has protein in it should turn purple is not it will stay blue.

The Benedicts test

Aim: To test a sample of food the determine whether it contains simple sugars

Equipment: Bunsen burner, test tube tongs, Benedict's solution, a sample of food

Method:

1. Place about 2 ml of the sample into a test tube then add 5 drops of Benedict's solution.
2. Heat with a bunsen until it changes colour. Do not boil

Results: A positive test for simple sugar results in the Benedicts Solution changing from a blue colour to an orange colour. No colour change is a negative result.

Conclusion the Benedicts solutuion changes colour the the sample is simple sugar