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Moist-heat cooking · beginner

Blanching

Briefly boiling food, then stopping the cooking in iced water.

49 recipes use it

What it is

Blanching plunges vegetables, nuts or fruit into boiling salted water for a short time, then into iced water. It is used to set green colour, soften vegetables before stir-frying, loosen tomato and almond skins, and prepare vegetables for freezing.

Why cooks use it: It partly cooks food evenly and quickly, keeps green vegetables bright, and inactivates enzymes that would otherwise spoil colour and flavour in the freezer.

The science

Brief heating drives air from plant tissue (making greens look brighter) and inactivates enzymes that cause browning and off-flavours. Long cooking or acid converts bright chlorophyll to olive-coloured compounds, so speed matters.

How heat moves into foodAcids and bases in cookingEnzymatic browningThe science of drying

Step by step

  1. Bring a large pot of well-salted water to a rolling boil.

  2. Prepare a bowl of iced water.

  3. Add the food in small batches so the boil returns quickly.

  4. Cook briefly: from 15–30 seconds for tomatoes and spinach to 2–3 minutes for beans.

  5. Lift straight into the iced water until fully cold.

  6. Drain well and pat dry.

Heat and timing

  • Blanching 100–100 °C · Boiling water, then iced water close to 0 °C.

Time: 15 seconds to 3 minutes.

How you know it’s right

  • Colour turns vivid green
  • Tomato skin splits at a scored cross
  • Vegetables tender-crisp when bitten

Common mistakes

  • Too much food at once
  • Skipping the ice bath so food keeps cooking
  • Adding lemon or baking soda to the water

Troubleshooting

Greens turned olive-drab
Cook for less time, use more water, and chill immediately.
Palak gravy dull green
Blanch spinach for under a minute, chill, and add the purée at the end of cooking.

Restaurant DNA

How professionals do it

Kitchens blanch large quantities of vegetables before service, chill them, and finish them to order in butter or a sauté pan; the step is called 'refreshing' when the food goes into iced water.

At home

Blanch vegetables ahead when entertaining, then reheat them in a pan for one or two minutes.

General professional practice — not any particular restaurant’s recipe.

Food safety

  • Use a slotted spoon, not your hands, to move food between boiling and iced water.

Practise it

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