P9 BIURET TEST

OBJECTIVES

We want to observe the quantity of proteins of eggs and milk, and of its different types and parts.

MATERIAL

·         Tube rack

·         5 test tubes

·         5 beakers 250 mL

·         Pipette

·         Distilled water

·         An egg

·         Milk: skimmed and whole milk

·         Soy juice

·         CuCo₄

·         NaOH

·         Weighing machine

·         Spatula

·         Glass stirring

·         Dropper

PROCEDURE

I will divide this experiment in two parts, to make it strictly.

PART 1

1.    We take 5 beakers and we indicate which substance we are going to add on it, and we put 100 mL of distilled water in every beaker.

2.    After that, we add 10 mL of one of those substances (soy milk, skimmed milk, whole milk, egg yolk, the egg white) in every beaker, with the help of a pipette.

3.    Then we remove it with the help of a glass stirring.

PART 2

1.    We take five test tubes and we indicate again which substance we are going to add on it, the content of each beaker.

2.    We add in every test tube 2 mL of one of the beakers, different in each tube.

3.    We put 2 mL of Na OH dissolution 20% (20 g of NaOH and 80 g of distilled water).

4.    Finally, we add 5 drops of CuCO4 1% dissolution (1 g of CuCO4 and 99 g of distilled water).

RESULTS  

If we observe the results are:

1.    Egg yolk. (colour dark purple)

2.    Soy juice. (colour purple)

3.    The white egg.  (colour dark blue)

4.    The whole milk.(colour blue)

5.    The skimmed milk. (colour blue- grey)

CONCLUSIONS

Biuret Test is used to reveal the quantity of proteins that a substance has, depending on the result colour.

The substance that has more quantity of proteins is which is close to the colour black, then the colour purple, blue. The substance with the less quantity of proteins is close to the colour grey. 

In the results is already arranged from which has more proteins to which has minus quantity of proteins.