Question

1. What can you conclude about the molecular make-up of egg whites based on the test you performed? Why might these foods contain these substances?

Answer 1

In the given case, Biuret test was performed to check wheatear a given sample has protein content or not. The biuret reagent helps in the identification of the protein content in the solution. The biuret reagent composed of potassium hydroxide and copper sulfate. When the biuret reagent mixes with the protein, the blue color reagent (original biuret content) will turn into the violet color. The violet color in the test tube indicates the presence of the protein. The peptide bonds in the protein react with the biuret reagent results in the strong color change (blue to violet) Mechanism: along with the sodium hydroxide and copper sulfate, biuret reagent also contains potassium sodium tartrate. The combined latter is added to the chelate and stabilize the cupric ions. Under the alkaline condition, the cupric ions react with the nitrogen atoms in the peptide bond of protein, results in the displacement of the hydrogen atoms in the peptide. Due to the chelation of the peptide nitrogen, the color change is observed NH O R. N NH cu2 Cut2 OH R + NH R NH HN (protein) Biuraet complex (pink or voilet blue) The contained results from the observations is as follows: Protein Initial Color Final Color Sample Present 1 - Albumin Solution 2- Gelatin Solution Clear yellow Sticky purple Clear Purple Yes Yes Clear No 3 Glucose Clear 4 Water Clear Clear No 5- Unknown Clear foggy Clear foggy No

1) Egg whites are proteinaceous in nature, and they are rich with a protein called Albumin For example, an egg contains about 11 grams of protein, and so if one performs a biuret test on egg white, then the final color will be purple. The total egg white contains 10% of protein and 90% of water. Since they are purple in colour they are rich in proteins. Eggs that humans consume are fertilized eggs, however, a chick never develops in it. There are two main regions in an egg, namely a central yellow part and germinal center. The yolk which is surrounded by white albumin and the germinal center in the yolk which gives rise to the embryo. The main reason that egg yolk and mainly the egg white contains a large amount of protein is to nourish the developing chick embryo.