Cooking method

Boiling

Boiling is the most violent way to cook. Water at 100°C churns, and that movement breaks things up, leaches flavour out and tightens protein — which is why it is right for a short list of foods and wrong for most of the ones it gets used on.

Why boiling is a blunt instrument

Water cannot go above 100°C at ordinary pressure, so boiling delivers heat at a fixed temperature — but it delivers it very efficiently, because water conducts heat far better than air and the movement keeps fresh hot water against the food.

That efficiency is the problem as much as the benefit. Protein tightens and squeezes out moisture faster at 100°C than at 90°C, so boiled meat is dry and stringy. Delicate things physically fall apart in the churn. And anything soluble — sugar, salt, flavour compounds, some vitamins — leaches into water that then goes down the sink.

Almost every dish that says "boil" would be better at a simmer. The exceptions are the ones where the agitation and the volume are doing something useful.

What boiling is actually for

• Pasta. Movement stops it sticking, and the volume of water dilutes the released starch.
• Green vegetables, briefly. A large volume at a hard boil recovers temperature fast and cooks them in two or three minutes, which is what keeps the colour.
• Potatoes and root vegetables destined for mash, where leaching does not matter and you want them cooked through.
• Reducing, where evaporation is the whole aim and there is nothing delicate to damage.
• Blanching, where the point is a violent short shock followed by iced water.
• Eggs in the shell, protected by the shell — though a simmer gives a gentler, less rubbery white.

What boiling ruins

• Stock. A boiled stock is cloudy and greasy because fat emulsifies into it, and it cannot be skimmed back out.
• Stews and braises. Boiling tightens the muscle fibres and squeezes out moisture faster than collagen converts, giving dry meat in liquid.
• Fish and delicate vegetables, which disintegrate.
• Beans and pulses, whose skins split and whose interiors turn to mush.
• Custards and anything with egg or dairy, which curdle.
• Rice, which needs a bare simmer under a lid to absorb rather than to be knocked about.

Salting the water

Pasta water

Generously — it should taste noticeably salty. It is the only chance to season the pasta itself, and most of the salt goes down the drain.

Green vegetable water

Well salted, for the same reason, and it helps the vegetables hold their colour.

Potato water

Salted. Unsalted potatoes taste flat however much salt goes into the mash afterwards.

Egg water

Salt makes no useful difference. A splash of vinegar does help a cracked shell set.

Does salt make water boil faster?

No. The amount you would add raises the boiling point by a fraction of a degree, which is not detectable in cooking time.

Beans and pulses

Salt them. The old advice that salt keeps them tough has been tested repeatedly and does not hold.

Common questions