PROTEIN CONTENT TEST (BIURET METHOD)

 PROTEIN CONTENT TEST (BIURET METHOD)

AIM:
To determine the protein content in a food sample.

APPARATUS:
Test tubes, measuring cylinder, colorimeter (optional), beaker.

REAGENT:
Biuret reagent (NaOH + CuSO₄).

PRINCIPLE:
Proteins form a violet-colored complex with Biuret reagent in alkaline conditions due to peptide bonds.

PROCEDURE:

• Prepare a 1% solution of the sample in distilled water.

• Add 5ml of Biuret reagent to 2ml of the sample in a test tube.

• Mix and allow to stand for 30 minutes.

• Observe color change or measure absorbance at 540 nm.

CALCULATION:
Compare absorbance to a standard protein curve or use visual intensity for qualitative estimation.