Glossary

Preferment: levain, biga, poolish and pâte fermentée explained

A preferment is part of the dough, fermented ahead of time and added to the final mix. Every tradition has one, because the same problem shows up everywhere: flavour and dough strength both take hours to develop, and a bakery cannot always give the whole dough those hours. Fermenting a portion in advance buys flavour, extensibility and keeping quality, and it shifts work to a time when the bakery is quiet.

The four you will meet

Preferment	Leavening	Hydration	Ferments	Gives
Levain	Wild yeast and bacteria from a starter	50 to 125 percent	6 to 16 hours	Sourness, keeping quality, strength from acidity
Poolish	Baker’s yeast, 0.1 to 1 percent	100 percent	8 to 16 hours	Extensibility, mild nutty flavour, open crumb
Biga	Baker’s yeast, 0.5 to 1 percent	45 to 55 percent	12 to 18 hours	Strength, sweetness, chew; long-keeping crumb
Pâte fermentée	A piece of yesterday’s finished dough	The dough’s own, usually 60 to 68 percent	Kept 6 to 48 hours, cold	Flavour and strength with no extra formula; already has salt

Hydration is expressed in baker’s percentage: the water as a share of the preferment’s flour.

Levain

The levain is the working portion of a sourdough culture. You keep a small starter alive by feeding it; before a bake you build a levain from it, sized to the recipe, so the starter itself never gets used up. The levain’s hydration is a choice: a stiff levain around 50 percent favours acetic acid and a sharper, more complex flavour; a liquid one at 100 percent or more favours lactic acid and a milder result. Temperature and ripeness decide as much as hydration, which is why the feeding schedule matters more than the recipe.

Poolish

Equal weights of flour and water with a pinch of yeast, left 8 to 16 hours. The amount of yeast is set by the time available: about 1 percent of the poolish flour for eight hours at room temperature, 0.1 percent for sixteen. A poolish is ripe when the surface is domed and just starting to fall, with a wrinkled top and a wine-like smell. It makes a baguette dough extensible and gives the crumb its creamy colour and irregular holes.

Biga

The Italian answer to the same question, but stiff. At 45 to 55 percent hydration the biga ferments slowly and develops less acidity, so it can go longer, often 16 to 18 hours at 18 °C, and it gives strength rather than extensibility. That makes it the preferment of choice for ciabatta and other very wet doughs, where the biga’s structure holds up a dough that would otherwise spread. Breaking a stiff biga into the final mix takes longer than pouring in a poolish; cut it into pieces and let it soften in the dough water for a few minutes first.

Pâte fermentée

Old dough. A piece of yesterday’s bread dough, fully mixed with salt and yeast, held in the fridge and added to today’s mix at 10 to 40 percent of the flour. It costs nothing to make and adds flavour and strength; the only thing to remember is that it already contains salt and yeast, so the formula has to account for both. Beyond 48 hours cold it becomes too acidic and weak to help.

Choosing one

Choose by what the dough lacks. A weak flour wants a biga. A tight, hard-to-shape dough wants a poolish. A bakery that wants sourness and a loaf that keeps for days wants a levain. A bakery that already makes a lean dough every day has pâte fermentée for free.

Many production bakeries run two: a levain for the sourdough range and a poolish for the yeasted range, built at the same time the evening before. Both are timed to be ripe at mix time, and both are built from the same arithmetic: the recipe’s prefermented flour percentage, times tomorrow’s flour, gives the quantity; the ratio and the room temperature give the hour.

Questions bakers ask

What is the difference between biga and poolish?

Hydration and origin. A poolish is liquid, equal flour and water, from the French tradition; it gives extensibility and a nutty, mild flavour. A biga is stiff, 45 to 55 percent water, from Italy; it gives strength and a slightly sweeter, more complex taste. Both use a small amount of baker's yeast and ferment 12 to 16 hours.

Is sourdough starter a preferment?

The starter is the culture you maintain. The levain is the portion you build from it for a specific bake, and the levain is the preferment. In practice bakers use the words loosely; the distinction matters when you count flour and water in the formula.

How much preferment should a dough have?

Expressed as the share of total flour that is prefermented: 15 to 30 percent for most breads. Poolish-based baguettes often use 30 to 50. Above that the dough ferments fast and can lose strength.

Related

• Sourdough starter feeding schedule, worked back from mix time. Feed the starter so it peaks at the moment you mix. The feeding ratio and the temperature are the two timers; set them for your mix time and the schedule writes itself.
• How long to bulk ferment sourdough, and how to tell when it is done. Bulk fermentation is done when the dough has grown 30 to 75 percent, domes at the edges and jiggles as one mass. At 24 to 26 °C that takes four to six hours.
• Baker's percentages, explained simply. In baker's percentages, flour is always 100 and every other ingredient is a share of the flour. Water 70 means 700 g of water per kilo of flour, at any batch size.

Sources: Hamelman, Bread, 3rd ed.; Suas, Advanced Bread and Pastry; Calvel, The Taste of Bread. Updated 2026-09-09.