A poolish is what’s known as a pre-ferment, which is a fancy way of saying that it’s a small amount of water and flour combined with commercial yeast ahead of the main bake to create the leavener for a recipe. The yeast ferments the flour and water to create something that’s similar to a sourdough starter, but is ready in hours, rather than weeks. It has a much milder flavor than sourdough, and delivers enhanced flavors and improved textures when used in dough.
The main difference between a sourdough starter and a poolish is that a sourdough starter is made with wild yeast and contains lactic acid bacteria, whereas a poolish is made with commercial yeast. This means that the commercial yeast works a lot more quickly, making the poolish ready to use within hours, rather than weeks, like with a new sourdough starter. Both are considered pre-ferments, because both the wild and commercial yeast ferment the flour and water they are combined with.
Using a poolish is a great way to create depth of flavor and better texture in your bakes. It is much more mild than sourdough, and lacks the sourness, so it’s a great option for bakes where you want the benefits of some fermentation, but without the strong flavor profile.
A poolish is also much faster to prepare than a sourdough starter. While it takes weeks for a new sourdough starter to get established and be ready to leaven bread, a poolish can be made 12 to 24 hours in advance of baking, before it is ready to use. The dough made with a poolish also does not require as much rise time as sourdough does: while you can absolutely do a cold proof for a longer fermentation time, poolish dough generally only needs 2-3 hours of rise time, similar to other doughs made with commercial yeast.
Making a poolish is simple, and takes very little hands-on time. While some recipes may call for different amounts of flour and water, the ratio will always be 1 part water to 1 part flour. Here’s how to make a poolish at home: