D20071029504...eggs...

In my opinion, the grade of an egg not determines the protein content in it. This is because determination of grade in egg is comes from other aspects. Classification determined by interior and exterior quality and designated by letter AA, A and B. In the grading process, eggs are examined for both interior and exterior quality and are sorted according to weight or size. Grade quality and size are not related to one another. In descending order of quality, grades are AA, A and B. There is no difference in nutritive value between the different grades.

Below are the qualities of egg:

	Grade AA	Grade A	Grade B
Break Out Appearance	Covers a small area.	Covers a moderate area.	Covers a wide area.
Albumen Appearance	White is thick and stands high; chalaza prominent.	White is reasonably thick, stands fairly high; chalaza prominent.	Small amount of thick white; chalaza small or absent. Appears weak and watery.
Yolk Appearance	Yolk is firm, round and high.	Yolk is firm and stands fairly high.	Yolk is somewhat flattened and enlarged.
Shell Appearance	Approximates usual shape; generally clean,* unbroken; ridges/rough spots that do not affect the shell strength are permitted.		Abnormal shape; some slight stained areas permitted; unbroken; pronounced ridges/thin spots permitted.
Usage	Ideal for any use, but are especially desirable for poaching, frying and cooking in shell.	Ideal for any use, but are especially desirable for poaching, frying and cooking in shell.	Good for scrambling, baking, and as an ingredient in other foods.

*An egg may be considered clean if it has only very small specks, stains or cage marks. Source: USDA

Egg composed of shell, air cell, shell membranes yolk, vitelline membrane, albumin and chalazae.

The total concentration of protein for example egg can be determine by doing Lowry Assay experiment. The principle behind the Lowry method of determining protein concentrations lies in the reactivity of the peptide nitrogen[s] with the copper [II] ions under alkaline conditions and the subsequent reduction of the Folin-Ciocalteay phosphomolybdicphosphotungstic acid to heteropolymolybdenum blue by the copper-catalyzed oxidation of aromatic acids. The Lowry method is sensitive to pH changes and therefore the pH of assay solution should be maintained at 10 - 10.5.

The result that we get from the Lowry assay is that when the density of protein is higher, the absorbance is higher. The concentration of protein can be determine from the graph that we sketched.