Whether you use a Levain, a Poolish, a Biga, or even a Pâte Fermentée to rise your dough, let’s be clear about one thing:
They do the same thing and make your dough expand!
That’s their basic function, no more, no less. Now you could argue that they provide certain characteristics such as extensibility and a sour tang. But their most basic characteristic is to make dough rise.
I realize that the whole preferment thing can be intimidating for many people. But using a preferment is literally thousands of years old. But it seems that it wasn’t until this pandemic lockdown that people jumped on the artisan bread making bandwagon by the millions (that includes me, by the way) and this seeming mystique was built around sourdough and preferments. Which is probably one of the reasons I started this blog other than to chronicle my journey.
To me, there is no mystery behind making bread and absolutely no mystery behind preferments. To be clear, a preferment is simply a portion of your dough that has a high density of yeast and flavor-producing bacteria. It helps the larger portion of your dough rise faster.
Technically, you could leave a mixture of flour and water out and eventually the wild yeasts and bacteria will infect the mixture and ferment your dough. But that takes a long time – several days. But with a preferment, or even commercial yeast for that matter, you shortcut the natural fermentation process and effectively speed it up because you’re adding a high concentration of microbes to the dough to give it a head start.
Think of a preferment as simply a concentrate, similar to frozen concentrated orange juice. You add the concentrate to a host of some sort and it changes it. In this case, our yeast and microbe concentrate expands the dough to make it rise, and when heat is applied, produces bread. It’s really that simple. There’s no mystery.
If it’s that simple, then why use a preferment and not just go the easy route with instant or active dry yeast? Simply because a preferment has added functional and nutritional benefits that you don’t get with plain yeast. Functionally, the lower pH (more acidic) of a preferment aids in the extensibility and elasticity of the dough. Nutritionally, using a preferment produces amino acids and other healthful by-products that make the bread more easily digestible and also act as a natural preservative to aid in the bread’s shelf-life.
Is one preferment better than another? This is where it really boils down to personal preference and what you’re after as a baker and somewhat, the type of bread you’re making. But you see, there are no hard and fast rules. There may be conventions – for instance, using a poolish to make baguettes – but lots of folks, including myself, regularly break from convention. Even with brioche which, by convention uses commercial yeast can be made with a sourdough starter.
With bread, you can’t – and shouldn’t – be canonical. And beware of anyone who says such and such bread must be made with a specific type of ingredient and especially those who invalidate another’s choice of rising agent.