Poolish for pizza: the 100 % liquid preferment

What a poolish is

A poolish is a liquid preferment. You mix equal weights of flour and water, so 100 % hydration, with a little yeast, then let it ferment before folding it into the rest of the dough at the final mix. It is sometimes nicknamed “liquid biga”, which sums it up well: the same principle as biga, the opposite consistency.

Like any preferment, it gives the final dough part of its character through the acidity it develops while resting. But its very high hydration changes what it brings in a fundamental way.

A quick mix, by hand

Its liquid consistency dictates the method: poolish is made by hand, not in a mixer. Dissolve the yeast in the water first, then add the flour. The mix is very quick, 2 to 4 minutes, just long enough for a smooth, lump-free batter.

The final temperature: 22–25 °C

I aim for a poolish at 22–25 °C (72–77 °F) at the end of mixing. That is slightly cooler than a biga, which finishes at 25–26 °C. To get there, the ingredients must be tempered: with cold water and cold flour, fermentation struggles to start. Keep them between 18 and 26 °C (64–79 °F).

If the poolish then goes into the fridge, the rule is the same as for any dough: a pause of about one hour at room temperature first, so that fermentation starts before the cold.

Which flour?

As with biga, I use a strong flour, above W 300. The stronger a flour, the more water it absorbs and the better it copes with long rests: two qualities a poolish needs. The exact strength is then chosen for the pizza, because that is what lets you find the balance between strength and extensibility in the final dough. To read a flour spec sheet, see flour: W, P/L and ash.

How much yeast, how long?

There is no universal dose: the amount of yeast depends on the fermentation time you want, and is reasoned for a reference temperature of around 20 °C (68 °F). The two go hand in hand:

• little yeast means a long wait, up to 3 days in the fridge;
• a poolish ready the next day needs more yeast.

For a poolish that ferments entirely at room temperature, here are reference doses of fresh yeast, as a percentage of the poolish flour, for a 100 % hydration poolish coming out of the mix at 26–29 °C (79–84 °F):

In a cooler room the poolish will ferment more slowly: go by the signs of readiness described below first.

In practice, a poolish kept in the fridge after its pause at room temperature usually ferments for 16 to 20 hours, and can go up to 72 hours if you want a more developed flavour. It can make up anywhere from 30 to 60 % of the total dough.

How to tell it is ready

Two signs, to be read together:

1. it has doubled in volume;
2. it is starting to give way in the middle: the domed surface dips slightly at the centre.

That is the moment for the final mix.

What poolish brings

• Marked extensibility in the gluten network, thanks to its high hydration and more intense enzyme activity.
• A distinctive flavour profile, different from biga, because the organic acids it produces are not the same: acetic acid dominates.
• A more uniform crumb, more regular and finer than a biga’s.

Poolish or biga: side by side

Between the two, the choice is mostly personal. If you are still deciding between a preferment and a straight dough, start with direct or indirect.

The practical constraints

Poolish is simple to make, but it has its demands.

• Hand mixing and a liquid consistency make it harder to manage in a professional setting than a biga.
• You have to plan ahead: at least one night of fermentation, often more.
• Ingredient temperature matters from the start, or fermentation will be sluggish.
• The final mix needs malt: like any long fermentation, the poolish’s reduces sugars and enzyme activity. About 2 % malt syrup or 1 % malt powder makes up for it.
• The final dough is wetter: an indirect contemporary Neapolitan sits at 70 to 75 % total hydration. A sticky dough at the final mix is normal; a mixer helps if you are starting out.
• The poolish’s temperature affects the dough’s: straight from the fridge it cools it; left at room temperature it warms it.

After the final mix

For a poolish dough, the final mix does the job that kneading does in a direct dough: the fermented preferment meets the remaining flour, water, salt and, where used, malt and yeast. The temperature target does not change: dough that comes out at 23–25 °C (73–77 °F).

What follows benefits from all the work the poolish has already done. An indirect dough ferments faster than a direct one: after balling, the dough balls are usually ready after 3 to 4 hours at 22–25 °C (72–77 °F). At room temperature I bake them within 4 to 6 hours. Put in the fridge straight after balling, they keep for 24 to 48 hours; I then take them out about an hour before baking.

To organise these steps, use the dough schedule.