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Cloudy water is useful water

Why Do Cooks Save the Pasta Water?

The cloudiness is starch, and starch is what makes a sauce cling.

Plain water Sauce slides off thepastaStarchy pasta water Sauce clings to everystrand
The cloudy stuff most people pour away.

  1. Step 1 of 5

    Pasta leaks starch as it cooks.

    Cooking pasta Starch dissolvinginto the waterThat is what the cloudiness is

    Hot water pulls starch off the surface of the pasta. Those long molecules spread through the pan and make the water cloudy.

  2. Step 2 of 5

    Starch thickens liquid.

    Water Runs offStarchy water Thick enough to coat

    The molecules tangle with each other and get in the way of the water flowing, so even a little makes a sauce noticeably thicker.

  3. Step 3 of 5

    It also helps oil and water mix.

    1 Oil and waterseparate2 Add starchywater3 They holdtogether as asauce

    Starch holds oil droplets apart so they stay suspended instead of separating. A splash turns a split, greasy sauce back into a smooth one.

  4. Step 4 of 5

    Salt in the water seasons from the inside.

    Salted water Seasoned all the waythroughSalted afterwards Only the outside tastesof it

    Pasta absorbs water as it cooks, and whatever is dissolved in it comes along. Salting later only ever seasons the surface.

  5. Step 5 of 5

    Which is why the last minute happens in the pan.

    1 Nearly cooked2 Move into thesauce3 It finishescooking in theflavour

    Finishing the pasta in the sauce with a splash of its water lets it absorb flavour and lets the starch pull the whole thing together.

    Rinsing cooked pasta washes off exactly the starch you have just spent ten minutes making.

The short version

Pasta water is full of starch, which thickens a sauce, holds oil and water together, and makes it cling.

Try it yourself

Put a spoon of oil and a spoon of water in a jar and shake — it separates. Add pasta water and shake again.

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