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Starters and Ferments

Confused by ferments and starters? We get lots of email enquiries and posts on our Facebook page about this subject. We thought it was worth a Focus of its own for anyone else out there confused by the issue.

Here’s a typical question and a guide to the various starters and ferments you’re likely to come across:

“Is anyone there able to explain the distinctive differences in terms of the whole sourdough process between wet starter (I thought it was called pate) and the firmer one (biga)? I tried to dig it in the past but always ended up lots of terminology. In these few years, I always feed and keep my starter rather wet condition and think whether it will be different if I turn them into biga. Big question??”

It is a big question and an issue which can be confusing to the novice baker. Firstly all sourdoughs use a starter, but not all breads that use a starter are sourdoughs. Confused already? Sourdoughs use only natural/wild yeast starters whereas some of the starters you mention use added yeast in the form of live or dried yeast added into the dough. Hopefully this will become clearer as we go along.

The likelihood is that every individual baker will give you a different answer. As a relative novice compared to some of my colleagues, I find Peter Reinhart in “The Bread Baker’s Apprentice” gives the simplest explanation:

What is a Starter or Ferment?

A starter or pre-ferment is used a base for your dough. It involves a preparatory step to making your dough rather than a simple dough which is mixed with ingredients that have not undergone any previous mixing or fermentation. The process of producing your pre-ferment is also much slower than making a simple dough. This extended fermentation can be used to develop enhanced flavour or texture and can also make the bread more digestible.

Reinhart identifies four types of pre-fermented dough (“starters”) which are commonly used. Two types of firm, or dry, pre-ferments and two types of wet, or sponge, pre-ferments. The firm pre-ferments are known under their European names "Pâte fermentée" and "biga". The wet pre-ferments are called “poolish” and “regular sponge” (the latter is also known as “levain levure” in French and “Mother” in English.) They all have different characteristics with further variations of each of them creating the possibility of endless types of pre-ferments.

To summarise each of the types:

Pâte Fermentée

"Pâte fermentée" is a French name meaning pre-fermented or “old dough”. Made by simply saving a piece of dough from one batch to use later or making a dough specifically to save and use later (this could include doughs made using added yeast which you would not therefore use later in a sourdough). Effect: immediately ages a newly made dough and therefore improves flavour.


Biga” Italian style, firm pre-ferment. Differs from pâte fermentée in that it has no salt. It is specifically made to be used as a pre-ferment. The absence of salt means it uses less yeast to accomplish the necessary fermentation, minimising the flavour of the yeast and maximising the flavour of the grain. It is used in breads such as ciabatta, focaccia and panini. In Italy nearly every pre-ferment, including wild yeast or sourdough, is called a biga. So if you are making a recipe make sure you check to see exactly what kind of biga (wild yeast/added yeast) it requires. Our own recipe for biga is from Salah Bournemman who teaches our “Discover Italian Baking” day. His own particular recipe produces quite a wet biga compared to Peter Reinhart’s description of it as a “firm” pre-ferment, which just goes to demonstrate that every baker has their own variation on the original.


Poolish” is a French term honouring the Polish bakers who, centuries ago, taught the French this technique. It is a wet sponge with equal weights of water and flour, no salt and 0.25% fresh yeast to flour (even less than biga). The wet texture offers less resistance to fermentation than a firm dough thus less yeast can be used in the ferment although additional yeast is usually (but not always) added in the mixing of the final dough to complete the leavening. (Thus not a starter that would be used in a sourdough).


A “Sponge” is faster than a poolish because all or most of the yeast is added to the sponge itself. Often used in whole-grain or rich breads to improve flavour and digestibility but in less time than a poolish. The front-loading of the yeast into the sponge means that the final mixing can often be done approximately an hour after the sponge is made.

There is often confusion regarding the terminology surrounding pre-ferments. Some bakers refer to all pre-ferments as sponges, whether they are made with commercial yeast or wild yeast, whether they are firm and dry, or wet and sticky. Others only use the term sponge for wet, fast-acting pre-ferments. Some breads are made with a fast-rising sponge others with a slow acting sponge. Regardless of how they are made or what they are called, they are all part of the family called pre-ferments, that is, dough that has been fermented in advance and added to another dough as part of a building process.

If you want to be sure of the finished result then you’re best off following the guidance in your recipe. However, as our great leader here at the Mill often says, there’s only one way to learn about dough and that’s to roll your sleeves up, get your hands stuck in and try it out. You’ll only learn about the different flavours and textures produced by different ferments by trying them and if you discover your own variation that works for you then give it a name!

Anyway this is just my own understanding (and heavily reliant on Peter Reinhart’s explanation). No doubt this may start a huge debate amongst everyone out there and everyone will likely have their own opinion. Tell us what you think everyone!

Happy Baking!