Poolish, levain, biga, pâte fermentée – is there a difference? And what’s the point in preparing a part of the dough separately? In this post, I’ll try to clarify the terminology and the science behind the wonderful world of preferments.

What is a pre-ferment?
A preferment is a portion of dough that is mixed in advance of preparing the final dough. Its main purpose is to increase flavour, strength, and shelf life. Because it is mixed ahead of time, bulk fermentation as well as mixing time is reduced. Preferments can be stored either at room temperature or in the refrigerator overnight, those that are stored in the fridge often assume more of an acidic flavour profile while room temperature preferments have a lactic flavour.

Preferments can be grouped into two categories: those that use commercial yeast, and those developed with wild yeast. Naturally-leavened starters require continuous attention and feeding to maintain, and can be kept alive for years, whereas other preferments made with commercially manufactured yeast  have limited life expectancy. In both cases, the amount yeast is dependent of the duration of ripening phase as well as the temperature of its environment. Different preferments are used in different recipes because they ripen at different times due to the amount of yeast used and their hydration levels. *** For the most part, you can use any of these types of preferments for a given recipe, so long as you adjust the amount of water (hydration) of your final dough. Here is a rough breakdown of the general characteristics of each type:

Poolish
– wettest pre-ferment,  1 to 1 ratio between flour to water with a small percentage of yeast (0.03 to 0.5%), 100% hydration, mix 3-18 hours ahead of time.
– should be made fresh every time, but can be refrigerated for a few days/ or frozen
– easy to incorporate into dough
– makes dough easier to shape, increased in loaf volume
– sweet, nutty, slightly lactic
– ideal for breads such as baguette
– % to add to dough (20-70)

Biga
– firmer than a poolish, 60-65% hydration with yeast of (0.24 to 0.33%), mixed 12 hours before using
– generic Italian term for “pre-ferment”,
– acid profile
– ideal for pane francese
– % to add to dough (50-75)

Sponge
– normally a hydration of 60 to 63% with yeast of (0.1 to 0.2%), mix 12 hours before using, sponge does not have sugar or fats and gives the yeast a chance to jump start the fermentation process
– idea for enriched doughs
– % to add to dough (15-25)

Pate Fermentee (old dough)
– fully fermented dough from a previous batch saved to be added to the new batch so hydration varies, removed after bulk fermentation, stored in a container refrigerated overnight for 12 to 14 hours
– added after the clean up stage the next day
– adds strength and imparts acidic flavour from cold storage
– can be made 6 hours ahead, and up to 18 hours
– flour, water and yeast are mixed for about 3 minutes on first speed
– make sure that the flour is hydrated

Levain
– highest hydration (usually around 100% for liquid levain, though firm levain will be lower)
– wild yeast and bacteria cultivated from the environment
– needs to be grown and developed over several weeks, but if fed can live for years
– feeding frequency varies with temperature
– should be used within 18 hours after feeding
– more details to come on a levain-specific post

Reference
Myhrvold, Nathan and Migoya, Francisco. (2017) Modernist Bread. Bellevue, WA: The Cooking Lab.
Hamelman, J. (2012). Bread: a bakers book of techniques and formulas. Hoboken, NJ: Wiley.
Hitz, Ciril. (2012). Baking artisan pastries and breads: sweet and savour baking for breakfast, brunch, and beyond. Beverly, Massachusetts: Crestline.
Migoya, Francisco. (2010). The Modern Cafe. Hoboken, NJ: John Wiley & Sons.
Reinhart, Peter. (2010). The Bread Baker’s Apprentice: Mastering the art of extraordinary bread. Berkeley, California: Ten Speed Press
Reinhart, Peter. (2009). Peter Reinhart’s artisan breads every day. Berkeley, California: Ten Speed Press
Hitz, Ciril. (2008). Baking artisan bread: 10 expert formulas for better bread at home. Beverly, Massachusetts: Quarry.
Reinhart, Peter. (2006). Crust and Crumb: master formulas for serious bread bakers. Hong Kong: Ten Speed Press