Actually very easy

Boiled eggs

The beliefBoiling an egg is assumed to be guesswork, and the green ring around the yolk is blamed on a stale egg.

The truthA boiled egg is a question of temperature: the white sets at 62–65 °C and the yolk at 65–70 °C. The time decides when each is reached.

15 minutes

How to make it

What you need

4 medium eggs, fridge-cold
1.5 litres of water
A bowl of iced water

How the engine read this list (2 lines)

200 g	Eggs, medium	egg
1500 g	Water for boiling	water

An empty weight means that line could not be turned into grams — either the amount is open ("to taste") or the ingredient has no record here. Neither enters the sum as zero; they do not enter it at all.

Bring the water to a rolling boil in a pan wide enough to hold the eggs in one layer.
Lower the eggs in one by one with a spoon. Start the timer at once and turn the heat down to a steady simmer.
Choose the time: 6.5 minutes for a runny yolk, 9 for a jammy one, 11 for fully set.
When the timer goes, move the eggs straight into the iced water for three minutes.
Crack each at the broad end, where the air pocket is, and peel it under running water.

Why it works

Egg white is not one protein but a mixture that sets at different temperatures. Ovotransferrin starts to coagulate around 62 °C, while ovalbumin — most of the white — holds out to 80 °C. The yolk thickens at 65 °C and goes crumbly at 70 °C. In a fridge-cold medium egg lowered into boiling water, heat travels from the outside in: at 6.5 minutes the white is fully set and the yolk still dark and runny; at 9 minutes the yolk is firm outside and slightly moist in the middle; at 11 minutes it is set right through. Beyond 12 minutes the sulphur in the white is released as hydrogen sulphide and meets the iron in the yolk to form iron sulphide — the green-grey ring. Iced water does more than stop the cooking: the sudden chill shrinks the white slightly away from the membrane and makes peeling easier. A very fresh egg peels badly because of pH: a fresh white sits near pH 7.6 and clings to the membrane, and after a few days it rises towards pH 9 and lets go.

The rough sum

1700 grams going in

286 kcal in total

100% of the mass has figures behind it. This is the sum of what GOES IN rather than of what comes out. Wherever something evaporates, drains or ferments the two differ: a kilo of milk is 150 g of cheese.

Diets it qualifies for

Gluten-free Vegetarian Lactose-free

Storage & shelf life

How long it keeps

Fridge, in the shell: 1 week
Fridge, peeled, in a closed box: 2 days
Room temperature: No more than 2 hours
Freezer: Not advised: the white turns rubbery

Boiling washes away the natural coating on the shell and leaves its pores open, which is why a boiled egg spoils faster than a raw one. Cool it once it is out of the water, dry it and get it into the fridge within two hours.

When to bin it A rotten smell heavier than ordinary sulphur when peeled, a slimy white or a change of colour: throw it out. The green ring around the yolk is not spoilage; it is overcooking.

History

Where it comes from

The boiled egg is one of the oldest forms of cooking, as old as boiling water itself. In Anatolia it belongs to breakfast, to food for the road and to the morning of a feast day; the egg dyed at Easter and at Nowruz stands for spring and rebirth across many cultures. Timing it to the minute spread with the kitchen timer.

The knack

For young children, pregnant people, older adults and anyone with a weakened immune system, there is no Turkish assurance scheme for eggs, so cook them 11 minutes or use pasteurised eggs; do not give them a runny yolk.
A teaspoon of vinegar in the water helps if one cracks: white leaking from the crack sets fast in acid and plugs the hole.
For eggs that peel easily, use ones that are 5–7 days old.

The pantry