It took me many, many years to master the art of sourdough. When I say ‘master’ I say this with tongue in cheek. One never really ‘masters’ sourdough. It masters us. When we give in to what it wants, it behaves. When we try to fight it, inevitably it will lead us to a learning opportunity, if nothing else.
Prefermentation is a good example of this. I dislike the word, as it implies ‘before fermentation’. It also implies ‘early fermentation’, so it’s ambiguous. In addition, the term isn’t really descriptive of what it actually does. Apart from some sort of fermentation process, it is also a gluten growing and strengthening process. By the time flour has been softened and stretched around for a good few hours, gluten grows like crazy. This is really a big part of why prefermentation is important to making great bread.
I guess I need to roll things back a bit. Since I started writing about all things sourdough, the internet has educated people a lot. My first blog on this subject was written over twelve years ago, and the subject was very new and different to the outside world back then. As was the whole arcane practice of breadmaking; particularly sourdough. It was very ‘out there’. For me, it was part of bakery life.
Now it’s science. So for those of us who have not yet covered the subject in detail, allow me to elaborate. For the rest, I’ll get to the practical stuff shortly.
Prefermentation has been used for hundreds of years. Long before the internet. Throughout Europe, where the modern, fashionable styles breadmaking really began, prefermentation is considered to be an integral part of the breadmaking process - whether sourdough or yeasted bread is being made. Indeed, European bakers I have met see bread as bread, not ‘sourdough’ or ‘yeasted’. This is largely because of prefermentation - which literally turns any dough into a fermented dough. Here’s a few well known variations on the prefermentation principle, as practiced in different countries and regions:
A ‘poolish’ is a wet preferment. It’s generally one part flour to one part water, with about 1% yeast. Common through France and Europe.
A ‘biga’ is a firm, or dry preferment. It’s usually made at two parts flour to one part water with 1% yeast, so it’s like a dough. Also common, especially in Italian influenced bakeries.
A ‘young levain’ is another wet preferment. It is part of a series of ‘refreshments’ done from starter to dough in many bakeries with a sourdough in their bread range. It is like a poolish, except that it is a small amount of starter (rather than yeast) mixed with one part flour and one part water. While French in origin, this technique is widely used, especially in sourdough bakeries.
A ‘sponge’ is a term Australian bakers call another type of preferment. It is a similar ratio of flour to water, and usually involves fresh yeast (as opposed to powder), old dough, and / or overripe dough. What goes into it can vary - it is an all purpose preferment.
The common factor with all of these ways of prefermentation is that they are utilised by the baker ‘on the up’. This means that they are built upon at their peak of activity, or some time before it.
A preferment fails when it is allowed to ‘sink’. At sinking point, it becomes a starter, so it also becomes many times more powerful.
Letting your preferment go too far is like quadrupling the amount of yeast in your dough, while simultaneously pouring in vinegar. When a preferment is overripe, it will cause the dough to break down rapidly. It becomes acidic, and gluten is greatly affected by acid.
It is used at approximately 2% of the sponge weight, when the sponge is 50% of the dough. So this becomes 1% of the total dough weight. Those not mathematically inclined - these are seriously simple sums. Toughen up.
Mostly, a sponge is calculated as a percentage of the total dough weight. So if I wanted to make 2 kilos of dough, and my sponge was 50%, then my sponge would weigh 1 kg.
Breaking this down further - my 1 kg sponge, being one part flour to one part water, would be made up of 500 g flour and 500 ml water. There would also be 20 g starter in there (Yes, I know the sponge is actually 1020 g. Please, can the pedants just exit via the portal they buzzed in on now).
The percentage of sponge in your dough can be anything from 10% right up to 75%. If you experiment, you’ll discover that a smaller amount of sponge will allow for a slower fermentation, while a larger amount gets things moving along very quickly.
The degree of ripeness of the sponge is shown by the amount of gas it has produced. This gas is captured in gluten bubbles, so the more bubbles, the more ripe the preferment. I like my sponge to be nice and bubbly before I use it; however, an underripe sponge will still do a great job.
An overripe sponge, on the other hand, will bugger your dough really fast. Thus, I err on the side of under ripe. It’s safer. I would rather have a less than perfect crumb in my finshed bread than an overripe chunk of dough to deal with.
Temperature control is the tricky part. In summer, the sponge will ripen fairly quickly, but can be too warm to use in dough, or too active. I tend to want to cool it down before using it.
In winter, it can be too slow, and sometimes it’s hard to perceive any movement at all. I’ll be looking for places around the house (or the bakery) to warm it up.
The easiest way to assess the amount of ripeness in the preferment is to draw a line on the side of the container at the level the sponge is when it’s made. My experience has been that any rise at all is fine. It doesn’t have to double, but it does have to move a little.
I’ve been interchanging the words ‘sponge’ for ‘preferment’. I hope you understand. There are less syllables in the word ‘sponge’. Call it baker’s shorthand.
By no means do I mean anything to do with ‘cake’.
A preferment has a lot to do with getting a great ‘crumb’ in your bread. This is a little known fact. It doesn’t matter whether you are after a big open crumb, or a more even one - prefermentation creates the circumstances for a ‘shine’ on the crumb. Hold your freshly sliced loaf up to the light. If it’s well made, the surface of the crumb (baked gluten bubbles, if you want to be more scientific about it) will shine, or reflect light.
If it isn’t well made, the crumb will appear ‘matt’ - there will be no ‘shine’. It will look ‘dull’. The bread may taste good, and even have a pleasing mouth feel, at least when it’s freshly baked. However, when the bread cools down, if it isn’t well made, it will stale quickly.
That ‘shine’ begins with good prefermentation, and is helped along by good dough development (kneading or mixing). If you really delve into why a french baguette is the way it is, start at the prefermentation process. There will almost certainly be one going on in the bakery, no matter what the yeast is.
Bread, as they say, is bread.