10. The experiment was repeated using egg yolk and egg white. For both, an extra sample was left to be tested.
11. Steps 1 to 4 were repeated again using a piece of cooked meat.
Results:
Conclusion:
The egg white has more protein.
According to my results, the egg white appears to have more protein than the egg yolk as it turned into a darker purple when the copper sulphate was added to it.
The crushing of the sample of food at the beginning of the experiment helped us to increase the surface area. The further hydrolysis was then completed to form amino acids and short polypeptide chains. Once this was done, the solution was heated so that there was an increase in the energy for collisions, generating an increase in the rate of reaction. At the end of the practical, the addition of more water allowed an increase in the volume of solution to aid dissolving of the amino acids and polypeptides.
The experiment was firstly done with a piece of chicken meat, since animal sources of protein tend to be complete; this means that the test for protein would be positive and we would, as a result, have a control to compare the results from the egg yolk and egg white later on. Given that the result of the addition of copper sulphate to the sample of protein was the change of colour into violet, we knew that depending on the tone of the violet (darker or lighter) it meant that either more or less protein was present. If it turned out to be violet/lilac, then individual amino acids were present. If it turned indigo, then only small peptides were present; there wasn’t any further breaking of the chain into small individual molecules.
The results for the egg yolk suggest that it does have a lot of protein (small peptides broken down into individual amino acids as turned into lilac). However, compared to the sample of chicken meat, there wasn’t much protein in the egg yolk, as it gave a lighter violet.
As for the egg white, the results suggest that it has more protein than the chicken meat itself, for it gave a darker purple. However, one should not think that it was almost indigo because the protein only broke down into small peptides. What happened was that there were so many individual amino acids, that the colour of the solution, when the copper sulphate was added, was a very dark purple, darker than the control itself.
When the CuSO4 is added, the copper joins the amine functional group producing the change in colour.
In the end, egg yolk is the one which has both fat and cholesterol and the egg white the one which is healthiest as it contains more protein than the rest.
