Pre ferments make better sourdough bread!
What is a pre ferment?
A pre ferment is essentially anything used on the way to building a sourdough or other type of bread, which assists the leavening process. For example, a 'baker's sponge' is made of flour, yeast and water, and is a type of pre ferment. So too is a 'poolish', which is a very wet, lightly yeasted sponge. Another type of preferment is known as a 'biga', which is made like a dough, also with a small amount of yeast.
In this article, I'm going to walk through the basic sourdough sponge method. This doesn't include any yeast, except of course sourdough starter. It is especially useful if you are working with a dough starter, though it also enhances dough being made with a liquid starter too.
Pre Ferments are like natural bread improvers - apart from increasing the activity of the yeast, they serve to elasticise the gluten, which gives you a better rise.
Gluten is 'gluey' - so it grows naturally by simply exposing flour to water. Thus, a preferment also assists in making dough by helping to create gluten without needing to knead!
Making a sourdough sponge (or preferment)
A 'sponge' is a baker's term referring to the creation of an active yeast colony, usually using flour, a little yeast, and warm water as the medium.
This is made as a batter, which is allowed to ferment, and physically resembles a 'sponge' when it's active. This sponge is then built into a dough using more flour, water, and a little salt.
It is useful to apply the sponge technique to sourdough, without refined yeast being added at all. This is especially important when using dough starter as the leaven. It also helps a liquid starter along too.
Interestingly, the texture of the preferment will carry through into the dough, and finally into the bread.
A preferment, in general terms, is one part flour and one part water, with about half the amount of sourdough starter (dough or liquid) you would normally use in the recipe you have chosen.
To apply the preferment technique to pretty much any recipe in this site, think of the recipe for dough in very general terms - that is, two parts flour and one part water.
Note: Water levels vary according to individual recipes - but these ratios are just a guide so you can easily get your brain around the technique.
So, when making a preferment, instead of simply proceeding with the recipe as usual, you add half the flour to all the water and the starter, and reserve the other half for later, after the preferment has done its thing.
Beat the starter into the water first, using a heavy type of whisk, or a fork. If you are using a dough starter, it's easier to break the starter up, then let it stand in the water for ten minutes before beating. This will soften it and make it easy to combine.
Now sift in the flour (remember, half of the total amount in the recipe).
You don't need to whisk very much at all if you want to make a loose textured sourdough - the batter created can be nice and lumpy. On the other hand, if you want to make a more even textured bread, whisk until you have a smooth batter. The choice is yours.
Now simply put a lid on your container and allow to stand. Fermentation will begin immediately.
Your container should have a bit of airspace for expansion - the sponge can double in volume.
We call a sponge 'viable' when bubbles are produced. So a sponge with only one bubble visible means there is fermentation taking place, as carbon dioxide is being given off - as evidenced by the bubble. However, the more bubbles you have, the better. So a sponge that is filled with bubbles is much better, and will allow you to make the dough more easily too.
A sponge can be left for a few hours or more, depending on the weather. You don't need to use warm water, but it does help in winter. In summer, I put my preferment in the fridge overnight, which is a really good thing to do as it helps gluten to form better in your dough.
Once your sponge is nice and bubbly, add in the rest of the flour and work it up to a rough dough. Then let it rest for about half an hour before adding the salt (autolyse technique).
You should notice that it is now possible to make a very shiny dough by hand, particularly if you work the dough on the bench giving it a few baker's turns.
Ultimately, bread made using a sponge is lighter, more flavoursome, and has better keeping qualities. Yes, there is a bit more work, but this is negated by the time you save in kneading the final dough.
Until next time,
Happy Sourdough Baking!