In the United States, eggs are given letter grades based on quality characteristics. You can read everything you need to know about how these grades are determined, which will help you understand the information in this article. The USDA egg grades are AA, A, and B, with AA being the highest grade. The egg’s freshness determines its true quality for cooking. However, most eggs sold at grocery stores are Grade A. This is perfectly good quality for most of our cooking needs. If you store a grade A egg too long, it will become a grade B egg.
All of these eggs, even the B grades, are still useful, just for different purposes. Any egg will work well in a recipe where the egg is incorporated. However, certain properties are present in fresher or older eggs.
Egg Quality for Frying, Poaching, or Cooked in Shell
Eggs that are AA quality, very fresh, will have high and firm yolks and thick whites that do not spread. A grade will have slightly thinner whites. B grade will be watery and thin. Even if you buy AA eggs, unless you use them at once, they will deteriorate to grade A eggs and beyond. This is why you won’t find many AA eggs at the store. By the time they get to you, they are no longer the highest grade. If they were, the price point would be much too high for most consumers. Since the eggs have already begun to age once you purchase them, and will continue to do so, you have no way to access their quality based on what the label says. Their appearance will tell you how good they are!
When you are serving eggs fried, poached, or cooked in the shell, ideally you want the freshest eggs possible. Break your eggs out into a separate container to judge the thickness of the white and the firmness of the yolk.
B-grade eggs will have yolks that are enlarged and slightly flattened. The smaller and firmer the yolk, the fresher the egg. Lower quality, older eggs will spread out like water.
For the most part, you simply want to avoid B-grade eggs frying, poaching, or boiling. This is especially important when poaching as it is difficult to master. For frying or boiling, A or AA should be fine for most, unless you are an obsessive foodie and insist on the freshest eggs possible. Most of us don’t have access to AA eggs unless we can buy fresh-laid eggs from a farmer.
Egg Quality for Eggs in Recipes
When you are going to incorporate your eggs into recipes with other ingredients, they can be older. For whipping, older egg whites will whip up to a greater volume!
Although we are often warned never to use an egg that is cracked, if the egg has been refrigerated and is going to be cooked very thoroughly, it should be fine, as long as it does not smell sulfurous. Cracked eggs should be used in recipes, therefore.
If you are dealing with older “B-grade” eggs and are unsure if they are too old, a sniff will tell you quickly. Good eggs have either no smell or a slightly sweet smell. On the other hand, the smell of bad eggs is hard to mistake. Any type of phosphorous or musty odor indicates an inedible egg.
You can also try the famous egg float test. This will not tell you much about what is happening inside the eggs but will generally indicate that an egg is getting too old, and may be spoiled.
Blood Spots, Green Spots, or Green Whites
If you find blood spots or germ spots in your eggs, as in the image above, these are harmless to you and it is up to you whether you can handle the idea that a bit of blood or the beginnings of germination are present. Obviously, you wouldn’t want to serve these fried or poached to guests. You may be able to remove the spot with the tip of a spoon.
Green whites could mean contamination by Pseudomonas bacteria. They may or may not have a sour odor. Discard any such eggs.
Sometimes when you crack an egg you may break the yolk. However, the white of a fresh egg is thick and the yolk is not watery, so the yolk will not mix with the egg white very freely.
On the other hand, if you break open an egg and the yolk is all mixed up with the white, causing the whole thing to be a murky mess, that’s a bad egg. This is called ‘mixed rot’ or an ‘addled egg.’
This may be caused by the yolk migrating and having become stuck to the shell, then dislodged upon handling, causing the membrane to burst.
At first, the yolk just seeps a little, and over time it becomes mixed with the white. For the yolk to have become stuck to the shell to the degree that it cannot be dislodged without breaking the membrane, it had to have been stored for a long period of time in a fixed position, indicating a VERY old egg.
Next See: Is It True That Yolk Color Doesn’t Influence Egg Taste?