Salt, vinegar and baking soda in egg water

Three things people add to boiling water for eggs. One does nothing, one helps a little, one helps in a specific situation. Tested against what is actually happening.

All three get recommended constantly, usually for peeling. Only one of them affects peeling at all.

Here is what each one does and does not do.

Salt: does nothing useful

The claim is that salt raises the boiling point so eggs cook faster, or that it helps them peel.

Salting water enough to matter for boiling point would mean roughly 58 grams per litre for a rise of half a degree. Nobody salts egg water that heavily, and half a degree would change a twelve minute egg by a few seconds.

For peeling it does nothing at all. The membrane is inside the shell and the salt never reaches it.

The one small benefit: if an egg cracks, salted water helps the escaping white set a little faster. Vinegar does that better.

Vinegar: useful for cracks, bad for flavour

Acid makes egg white coagulate faster. If an egg splits in the pan, a tablespoon of vinegar per litre turns a cloud of wispy white into a small firm plume you can lift out.

This is the same reason vinegar goes into poaching water, where it matters much more.

Use much more than that and it starts softening the shell and getting into the egg. You will taste it. There is no reason to add vinegar preemptively if your eggs are not cracking.

Baking soda: the one with a real mechanism

Baking soda raises the pH of the water. A more alkaline environment weakens the bond between the membrane and the white, so eggs peel more easily.

The effect is real but modest, and it is far smaller than simply using eggs that are a week or two old. Half a teaspoon per litre is plenty.

The trade off is that alkaline conditions also encourage the sulphur reaction that produces a green ring. If you are already cooking eggs slightly too long, baking soda makes the ring more likely.

What to do instead

• Use eggs at least seven days old. This beats all three additives combined.
• Start in boiling water rather than cold, or steam them.
• Move them into iced water the moment the timer ends.

If you want to add something anyway, baking soda is the only one with a mechanism worth the trouble.

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Egg guides

Common questions