|Fresh chicken egg cracked out of its shell|
Your grandmother may have had to check the freshness of farm eggs by dunking them, still in their shells, into water. The belief was that fresh eggs would sink and eggs you would not want to cook or eat would float.
This old wives’ tale is not entirely accurate, however. It is true that the air cell inside the eggshell enlarges as the egg ages. But floating eggs may still be safe to eat. Crack the egg into a bowl and check its appearance and smell before deciding whether to use or discard it. A spoiled egg has a distinctive sulfur-like odor known as “rotten egg smell.” If the egg smells OK, it is likely safe to cook with.
There is a better way to check the freshness of eggs you get from the grocery. Check the egg carton!
Eggs packed at plants that are under US Department of Agriculture (USDA) inspection have a pack-date number on the carton. These 3-digit numbers (called Julian dates) range from 001 to 365, and indicate the date (from January 1 through December 31) that the eggs were packaged. The American Egg Board states that raw eggs stored in their cartons in the refrigerator are safe to eat for four to five weeks beyond the Julian date.
Egg packing at plants not under USDA inspection comes under state laws for labeling. Most require a Sell-By or EXP date, which is a direction to the store, but is also the consumer’s guarantee of freshness for a couple of weeks past that date.
For a downloadable infographic explaining Julian and Sell-By dates and many other labels found on egg cartons, please see: https://www.incredibleegg.org/egg-types-packaging.