Biga vs. Poolish: Which Preferment Should You Use?

Both pre-ferment part of your flour the night before, but they're built completely differently. One is wet and forgiving. The other is stiff and needs meaningfully more yeast for the same build time.

Pizza technique

The core difference: hydration

A poolish is built wet: equal parts flour and water by weight, basically a thick, bubbly batter. A biga is built stiff, commonly around 44 to 50% hydration, closer to a shaggy, dry dough than a batter. That one difference in consistency is what drives almost everything else about how each behaves.

Why biga needs so much more yeast

At biga's low hydration there's far less free water around, so yeast activity and enzyme mobility are both a lot slower than in a wet poolish at the same temperature and time. The classical Italian biga formula, credited to Piergiorgio Giorilli, is about 1% fresh yeast on the biga's own flour, 16 to 18 hours at around 18°C. Run that same duration through a yeast-dose curve built for a wet, poolish-style dough and it comes out well under 1%, which is the gap biga's stiffness is actually paying for.

This matters in practice. If you've only ever built a poolish and switch to a biga using "similar feeling" yeast amounts, you'll seriously under-dose it, and end up with a biga that never really ripens.

How much of your flour goes in

Typical starting points: a poolish uses around 30% of the total flour, a biga around 50%. Both are ranges, not hard rules. A smaller poolish, closer to 20%, still works but carries less of the leavening, so the final dough has to do more of the work itself. A "100% biga," where the entire flour is pre-fermented, is also a well-known variant at the other end.

Which one for which situation

• Poolish: lighter, more extensible dough, a slightly more open and irregular crumb, and a milder, less acidic flavor. A forgiving, low-precision starting point for same-day to medium schedules.
• Biga: a stiffer, more structured final dough that holds its shape well, a cleaner and often "drier" crumb, and a flavor a lot of bakers describe as rounder and less tangy than poolish over a long ferment. Its stiffness also makes it a natural fit for longer, colder schedules. It doesn't slacken as fast as a wet poolish left in the fridge for days.

One thing that catches people out

Biga's own dose is calibrated for the classical case: build it, then use it the same day. Pair it with a long cold retard afterward instead (say, 48 to 96 hours in the fridge after balling) and that same classical dose can genuinely overdo it. The biga's yeast population doesn't stop working just because the final dough goes into the fridge. If you're planning a biga with a long cold follow-up, both the dose and, to keep the biga itself fully ripe, its own build time need to shift too, not just the follow-up schedule.