D20071029484 Lowry assay

In my opinion, the grade of eggs does not depend on the protein contain but it depends on the albumen, spread, yolk, shell, and use. There is no difference in nutritive value between the different grades. Classification determined by interior and exterior quality and designated by letters as AA, A and B. Grade AA eggs have thick, firm whites and high, round yolks. Their shells are clean and unbroken. Grade A eggs are like Grade AA, but their whites are reasonably firm. Grade A are usually sold in stores. Grade B eggs have thin whites and wider yolks. The shells are unbroken, but might show slight stains.

Egg Quality

	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

We can determine concentration of protein by using the Lowry Assay. If the density of Lowry is higher, the absorbance also higher. Its means, protein concentration also higher when the absorbance higher.