Poolish, biga or sourdough: which preferment to choose for your pizza

The short answer

• Poolish (100 % hydration, liquid): extensibility, big open cells, thin crisp crust, mild hazelnut flavour. The natural choice for a dough you want to stretch effortlessly and a rim that blisters.
• Biga (45 to 55 % hydration, stiff): strength, structure, a crumb that opens upward, more complex and slightly boozy aromas. The choice for very wet doughs and pan pizzas.
• Natural sourdough (wild culture, no added yeast): controllable acidity, deep flavour, keeping quality. The most demanding to manage and the least predictable without measurement.

In all three cases the question that matters is the same: at what time is the preferment ripe, and how much rise is left for the final dough? It is a matter of calculation, not intuition, and it is the one Fornello solves.

Poolish: extensibility and blisters

A poolish is an equal-weight mix of flour and water with very little yeast, left to ferment for 8 to 16 hours. Its liquid consistency favours enzyme activity and the production of mild organic acids. In the final dough it brings a remarkable extensibility: the dough stretches, does not spring back, and the rim puffs into large cells. The flip side is a slightly more fragile dough and a fairly narrow ripeness peak: a poolish past its peak collapses in the centre, smells of alcohol, and the final dough loses strength.

The poolish yeast dose depends on temperature and target time. For 12 hours at 20 °C we are talking a few tenths of a percent of the poolish flour, no more. Fornello computes that dose from its fermentation model, then estimates the ripeness window and how much of the total rise the preferment has already "spent" before it joins the dough.

Biga: strength and complexity

The biga is the traditional Italian preferment: stiff, often at 45 to 50 % hydration, fermented 16 to 24 hours somewhere cool (16 to 18 °C) or in the cold. In a stiff dough yeast multiplies more slowly and oxygen moves less: the aromas lean towards alcohol, fruit, sometimes a light cheesiness. The biga strengthens the final dough rather than relaxing it: that is why it is the base of very wet pizzas (75 to 85 %), contemporary or in teglia, where the network has to carry a lot of water.

Its difficulty is practical: a 45 % biga looks like coarse crumbs, and it has to be worked into the final dough by progressive kneading. An over-ripe biga smells strong and gives a dough that holds less. Temperature matters enormously: at 24 °C, a biga planned for 18 hours is past it in 10.

Natural sourdough: the flavour, at the price of management

A sourdough starter is a mixed culture of wild yeasts and lactic bacteria, kept alive by feedings. In pizza it gives a crust with deep flavour, an acidity you can dial (more cold and frequent feedings to soften it), and remarkable keeping of the dough ball. But its speed depends on the state of the culture, the temperature and the feeding ratio, three things few people measure. The result: most sourdough failures are under-fermented doughs (dense, pale) or over-fermented ones (flat, sour), not badly made ones.

Fornello treats inoculation as a power law: doubling the starter does not double the speed, because a smaller culture has more doublings ahead of it. It suggests an inoculation rate for your schedule, estimates the expected pH and character, and gives the feeding (1:5:5, for instance) and the peak time of your starter at your kitchen's temperature.

Comparing on the same pizza

The calculator below opens in poolish mode, on a contemporary Neapolitan. The leavening toggle switches to biga, to sponge and, at the advanced level, to Li.Co.Li. and sourdough. The engine recomputes the formula, the preferment dose, its ripeness window and the top-up yeast of the final mix. Change the preferment's duration or temperature and watch the window move.

Applying it to Neapolitan: which preferment, what share, what schedule

Traditional Neapolitan is a straight dough on fresh brewer's yeast: 0.1 to 3 g per litre of water according to the 2022 specification of the Associazione Verace Pizza Napoletana, which also allows a natural leaven at 5 to 20 % of the flour, for a total fermentation of 8 to 24 hours. Poolish and biga belong to contemporary Neapolitan, the one with the tall, open rim, and that is where they change the most. Three ways to do it, with the shares and schedules professional practice settles on, to adjust to your kitchen.

Ranges from professional practice, consistent with the contemporary Neapolitan windows in Fornello (water 65 to 78 %). The hours depend on your real temperature: a poolish planned for 12 hours at 20 °C is ripe in 8 hours at 26 °C.

The when question is the same for all three: the preferment must be ripe at mixing time, not an hour before nor two hours after. The calculator shows the ripeness window from the time and temperature you give it, then subtracts from the total rise what the preferment has already used, so the final dough receives exactly what is left. For a Friday-night Neapolitan, a poolish built Thursday at 8 pm and mixed Friday at 8 am, then 24 hours cold and a 2-hour final proof, is the most consistent schedule we know.

Which one to choose, concretely

• You want a dough that stretches easily and a rim that blisters, without managing a culture: poolish.
• You are going up in hydration (75 % and more), in a pan or contemporary, and the dough has to hold: biga.
• You want the flavour, you own a thermometer, and you accept feeding: sourdough, with an inoculation computed rather than guessed.
• You are unsure: start with a 12-hour poolish at 20 °C on a New York. It is the most forgiving preferment, and the difference from a straight dough is there from the first bake.