Eggs that are a week or so old are easier to peel than eggs that are only a few days old. Cooling them in cold water straight after cooking helps as well. The sources used here come from the United States and the United Kingdom, and the method suits any ordinary hen's egg.
Why fresh eggs are hard to peel
Inside every shell there is a thin skin, called the membrane, that lies against the egg white. British Lion Eggs says that eggs just a few days old stick to the shell more, and that the membrane loosens as the egg ages.
North Carolina State Extension gives a similar reason. It suggests that eggs bought 7 to 10 days before cooking have had time to take in air through the shell, and that this helps the membrane come away from the shell.
So if you plan to make boiled eggs, an egg that has been in the refrigerator for several days, and is still within its date, will give a neater result than one from the day it arrived.
Cooking the egg through
North Carolina State Extension describes a gentle method:
- Place the eggs in a single layer on the bottom of a saucepan.
- Cover them with cold water by about 2.5 cm.
- Heat until the water boils, then turn off the heat and cover the pan.
- Leave them for 12 to 18 minutes.
The same page gives timings by size: 9 minutes for medium eggs, 12 minutes for large and 15 minutes for extra large. It prefers the term hard-cooked to hard-boiled, because eggs that are boiled hard can turn rubbery and may develop a green ring around the yolk. British Lion Eggs adds that cooling the egg quickly also prevents a grey line from forming around the yolk.
Cooling and peeling
Both sources recommend cold water after cooking. North Carolina State Extension suggests an ice bath for 5 minutes. British Lion Eggs explains that the egg contracts slightly in cool water, which makes it less likely to stick to the shell, and suggests changing the water once or twice so that it stays cold.
To peel:
- Tap the egg gently on the counter until the shell is finely cracked all over.
- Roll it between your hands to loosen the shell.
- Start at the large end, where there is a small air pocket between the shell and the egg.
- Hold the egg under cold running water to help the shell slide off.
How long boiled eggs keep
Boiled eggs keep for less time than raw eggs in the shell. North Carolina State Extension says eggs in the shell can be kept up to 1 week in a refrigerator at 5 degrees Celsius or below, and that peeled eggs are best the same day.
Healthline, quoting guidance from the US Department of Agriculture, says boiled eggs should be cooled and refrigerated within 2 hours of cooking and kept on an inside shelf rather than in the door. It also says they should not be frozen, because the white and yolk turn tough and watery.
According to the same page, a greenish-grey layer on the yolk comes from cooking and is not a sign of spoilage. A slimy shell or a strong unpleasant smell is.
In short
- Eggs about a week old peel more cleanly than eggs only a few days old.
- Cook in water that has just boiled, off the heat, for 12 to 18 minutes, or about 9, 12 and 15 minutes for medium, large and extra large eggs.
- Cool the eggs in cold or iced water for about 5 minutes before peeling.
- Keep boiled eggs in the shell in the refrigerator for up to 1 week, and eat peeled ones the same day.
