Poolish

A poolish is a runny mix of flour, water and a small amount of yeast that you make several hours or a day before baking. It uses equal weights of flour and water, so it is 100 percent hydration. After it ferments, you mix it into the final dough. French bakers use it for baguettes, and it suits pizza and focaccia too.

How to do it

1. Mix equal weights of flour and water. For example, 200 g flour and 200 ml water.
2. Add a little yeast. How much depends on how long it will ferment:
   • 12 to 16 hours at room temperature: about 0.1 percent of the flour, a pinch of instant yeast.
   • 6 to 8 hours: about 0.5 percent.
   • 3 to 4 hours: about 1 percent.
3. Stir until smooth. It will look like thick pancake batter.
4. Cover and leave it at room temperature.
5. Add it to the rest of the flour, water, salt and yeast for the final dough.

How to tell it is done

A ripe poolish has doubled or tripled in volume and is full of bubbles on top. The surface has just started to dome or dip slightly in the center. It smells sweet and alcoholic, like beer. If it has collapsed a lot and smells sharp or like nail polish, it went too far, but it is usually still usable.

Why it works

Slow fermentation lets enzymes break down starch into sugars and lets yeast and bacteria make flavor. The wet mix ferments faster than a stiff biga and leans toward a mild, nutty, slightly tangy taste. The extra sugars help the crust brown and turn crisp.

Common mistakes

• Too much yeast for the time. It peaks early and the flavor gains are lost.
• A container that is too small. A poolish can triple and spill over.
• Using it long past its peak. The bread can taste sour and rise poorly.

In recipes

Recipes may say "prepare the poolish the night before" or give it as a share of the total flour, often 20 to 50 percent. It is a different thing from a sourdough starter, which is kept alive and fed and uses wild yeast.

Where it comes from

The name is thought to come from Polish bakers who brought the method to France in the 1800s.