======Biuret Test for Protein======


<WRAP right box>
**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
\\
**Categories:** {{$demo.categories}}
\\


**Alternative titles:** Testing Foods for Protein
</WRAP>

====Summary====                   
{{$demo.summary}}



====Procedure====  
  -Prepare Biuret solution by mixing equal volumes of 1% copper sulfate (Biuret A) and 1% sodium or potassium hydroxide (Biuret B).  
  -Warm gently in a 40 °C water bath until the blue precipitate dissolves.  
  -Add the food sample (e.g., egg white or milk) and mix well.  
  -Observe: a violet color indicates protein is present; blue means none.



====Links==== 
Biuret test for Protein - JamJarMMX: 
{{youtube>ufec89A47uM?}}\\

The Biuret test for Protein - CEEA Erasmus: 
{{youtube>z4ohqBeLMho?}}\\

📄 Biuret test for Protein - Revision World: [[https://revisionworld.com/gcse-revision/applied-science/aqa-additional-applied-science/unit-2-exam-topics/food-science/food-tests/biuret-test-protein]]\\


====Variations====
  *Test different foods such as cheese, beans, or meat extracts.  
  *Compare raw vs. cooked protein samples.


====Safety Precautions====
  *Avoid skin or eye contact; rinse immediately if contact occurs.  
  *Do not ingest test samples or solutions.  
  *Dispose of solutions safely in accordance with school lab rules.




====Questions to Consider====
  *Why does the Biuret test turn violet when protein is present? (The copper ions form a complex with peptide bonds.)  
  *Why is it useful to test both animal and plant foods for protein?  
  *How might cooking change the results of the Biuret test?