This information republished with permission from the American Egg Board.
1. What causes blood spots?
2. Why do some hard-cooked eggs have a greenish ring around yolk?
3. Is there a difference between brown and white shelled eggs?
4. How long will an egg keep?
5. What is the best way to store eggs?
6. Is it safe to eat raw eggs?
7. What are the stringy white pieces in egg whites?
8. Are eggs an economical food?
9. Are fertile eggs more nutritious?
10. Why are some hard-cooked eggs difficult to peel?
11. Why is an egg white sometimes cloudy or has a yellow or greenish cast to it?
Q: What Causes Blood Spots?
A: Small spots of blood (sometimes called "meat" spots) are occasionally found in an egg yolk. These do not indicate a fertile egg; they are caused by the rupture of a blood vessel on the yolk surface during formation of the egg. Most eggs with blood spots are removed during the grading process but a few may escape detection. As an egg ages, water moves from the albumen into the yolk, diluting the blood spot. Thus, a visible blood spot actually indicates a fresh egg. Such eggs are suitable for consumption. The spot can be removed with the tip of a knife, if you wish.
Q: Why Do Some Hard-Cooked Eggs Have a Greenish Ring Around the Yolk?
A: The harmless greenish ring is due to an iron and sulfur compound which forms when eggs are overcooked or not cooled quickly.
Q: Is there a Difference Between Brown and White Shelled Eggs?
A: No. Shell color is determined by the breed of hen and is not related to quality, nutrients, flavor or cooking characteristics. Since brown egg layers are slightly larger birds and require more food, brown eggs are usually more expensive than white.
Q: How Long Will Eggs Keep?
A: Fresh shell eggs can be kept refrigerated in their carton for at least 4 - 5 weeks beyond the pack date. Quality losses should be insignificant if the eggs are refrigerated as soon as possible after purchase from a refrigerated case.
Hard cooked eggs should be kept in the refrigerator for up to one week.
Q: What is the Best Way to Store Eggs?
A: Store eggs in their carton because eggs can absorb refrigerator odors.
Q: Is It Safe to Eat Raw Eggs?
A: The risk of food poisoning from eggs is highest with raw and lightly-cooked dishes. It's best not to serve raw or lightly-cooked dishes made with eggs.
Q: What are the Stringy White Pieces in Egg Whites?
A: These rope-like strands of egg white, called chalazae (ka-LAY-zee) are not imperfections or beginning embryos but a natural, edible part of the egg. They keep the yolk centered in the thick white.
Q: Are Eggs An Economical Food?
A: Eggs are a nutrient dense food and with 12 servings per dozen eggs they are great alone or used as a nutritious ingredient in baking or other prepared foods.
Q: Are Fertile Eggs More Nutritious?
A: Fertile eggs are not more nutritious than nonfertile eggs. They do not keep as well as nonfertile eggs and are more expensive to produce.
Q: Why Are Some Hard-Cooked Eggs Difficult to Peel?
A: Fresh eggs may be difficult to peel. Those which have been stored for a week to 10 days before cooking will usually peel more easily.
Q: Why Does an Egg White Sometimes Appear Cloudy or Have A Yellow or Greenish Cast to It?
A: Cloudiness of raw white is due to the presence of carbon dioxide which has not had time to escape through the shell and is an indication of a very fresh egg. A slight yellow or greenish cast in raw white may indicate the presence of riboflavin.