"How long are these eggs good for?" is one of the most frequent questions I am asked when I offer eggs to friends. In this post I will attempt to answer that question while also explaining why some hard boiled eggs are easier to peel than others. My source of information is the Chicken Keeping Secrets newsletter at chickenkeepingsecrets.com.
When an egg is formed, the yolk and whites are enclosed within a thin membrane. A second membrane lies just inside the egg’s shell. In a fresh egg, the two membranes lie against each other. In an older egg, evaporation has had a chance to occur within the egg because of the porous egg shell resulting in more space between the two membranes. When you boil a fresh egg, the two membranes lie so closely together that it is very difficult, if not impossible, to peel the egg. Use for old eggs for making boiled eggs.
You can use a “float test” to give you an idea how fresh your eggs are. The older the eggs, the larger the air pockets between the two membranes. The more air the eggs contain, the more they will float.
Fill a bowl with cool water. Gently place your eggs in the bowl.
(1) If the eggs lie flat on the bottom of the bowl, they are very fresh. These are the best eggs for eating alone.
(2) If the eggs stay in contact with the bottom of the bowl but one end starts to rise, these eggs are still fresh, just not quite as fresh as the one that lies flat.
(3) If the eggs stand on end but still stay in contact with the bottom of the bowl, they are still perfectly safe to eat but they are better used for baking or cooking. These are the eggs to use for boiling, since the air pocket between the two membranes is large enough to prevent sticking when peeling the shell away from the egg.
(4) If the eggs do not stay in contact with the bottom of the bowl, throw them away as they are not good for eating.
In the following photo, the brown egg is one day old. The white egg is a Safeway 'special' with a "sell by" date of October 30. As you can see, the white egg is already beginning to tilt upwards.
The reason store bought eggs usually peel so easily is because they are not very fresh. You may not realize this, but eggs can be more than 45 days old before you buy them. I do not know how long the “farm” has to package their eggs for sale once it has been laid. But at the time of packaging, the “sell by” date is 45 days later! In short, most of the eggs that you scramble for breakfast are likely 2 months old!
If your are lucky enough to get really fresh eggs, enjoy them as they are very special.