9.1 Biuret Test For Proteins

Question 1

What is the method for test for protein

Answer 1

1. Make eight food samples and add 2cm3 of each to test tubes and distilled water in 1
2. Using a pipette and holding the tube at 45 angle, allow 1cm3 of Biuret reagent to slide down the side of the tube, forming a layer on top of the sample
3. record any colour changes seen at the top
4. Shake carefully and gently to mix and allow to settle for 10 minutes Then record any colour changes and final appearance

Question 2

What is the positive result for the protein test

Answer 2

When Cu+2 Forms a peptide-copper complex, Biuret test identifies Presence of peptide bonds which changes the colour from blue to purple

Question 3

what is the chemical composition of Biuret Reagent and which of these chemicals are hazardous

Answer 3

NaOH which Is harmful to the eye and CuSO4

Question 4

Why do we observe with the Biuret as a layer on top of the sample before mixing

Answer 4

To see if there’s a colour change at the interface where they touch