Hard-to-peel boiled eggs

Fresh eggs peel badly, and that is chemistry

A fresh egg has a relatively low internal pH. At that pH the white binds tightly to the inner shell membrane, and when you peel it the white comes away with the shell.

As an egg ages, carbon dioxide escapes through the shell and the pH of the white rises. At the higher pH the bond is weaker and the shell lifts cleanly. Eggs one to two weeks old peel far more easily than eggs bought yesterday.

The air cell also grows as the egg ages, which gives you somewhere to start peeling. A very fresh egg has almost none.

The method that works

Hot start, cold finish.

1. Bring a pan of water to a rolling boil first, then lower the eggs in on a spoon. A hot start shocks the outer white into setting and shrinking away from the membrane.
2. Alternatively, steam them in a basket over boiling water. This works at least as well and is gentler on the shells.
3. Time from the moment they go in. Six to seven minutes for a soft centre, nine to ten for firm, depending on size.
4. Have a bowl of iced water ready and move them straight into it. The rapid contraction helps release the membrane.
5. Leave them in the iced water for at least five minutes.
6. Crack the shell all over by rolling the egg gently on the worktop, then start peeling from the wide end where the air cell is.
7. Peel under running water or in the bowl of water. It floats the shell fragments away and gets under the membrane.

What helps, what is folklore

Older eggs

The largest single factor. A week or two old is ideal.

Hot start

Genuinely effective. Lower them into already-boiling water rather than starting cold.

Steaming

As good as a hot start and gentler. Fewer cracked shells.

Iced water afterwards

Effective. The contraction helps separate the membrane.

Bicarbonate of soda in the water

Raises the pH and does help a little. Worth trying with very fresh eggs.

Vinegar in the water

Helps a cracked egg set rather than leak. Does nothing for peeling.

Pricking the shell

Reduces cracking. Little effect on peeling.

If they have already come out in craters

• Stop peeling them individually and switch to peeling under water, which gets between white and membrane.
• Use them where appearance does not matter — egg mayonnaise, a salad, a curry, a kedgeree.
• Chop them rather than halving them.
• Save the neatest ones for anything that will be seen whole.
• Note the date on the box and use those eggs for baking instead, where freshness is an advantage.

Common questions