43. How do I convert yeast bread recipes to SD recipes?
When converting recipes to sourdough I always make sure that I build my "sponge" with the smallest possible inoculum (usually a tablespoon). This way, you know exactly how much water and flour you are using (it's never easy to tell how much of what you're actually getting when you take starter directly from the jar unless you weigh the ingredients and maintain a 1:1 starter).
In general, I think it is a good idea to build a nice active sponge that contains somewhere between 5% and 20% of the total flour in the recipe. You will want to experiment with the percentage of sponge to see which results you like.
Here is a hypothetical example of what I mean: Let's say that the original recipe calls for 1000g of flour, 600g water, 20g salt and 20g yeast... If I wanted a 20% inoculum, I would make a sponge using 200g (20% of 1000g) flour, 300g water and one tablespoon of starter. Once the sponge was nice and active, I'd mix the sponge with 800g flour, 300g water and 20g salt. By using this method, I know that my dough has exactly the same amount of flour/water as the original recipe. At this point, all I have to do is mix the ingredients according to the recipe, proof and bake. The "new" version of the recipe should turn out very similar to the original, since the only substantial difference is in method of leavening.
Two things to keep in mind: 1. One cannot generally do multiple risings with sourdough as with yeast doughs. The rising schedules called for in the original recipe should be modified with this in mind. 2. The defining characteristics of certain bread styles seem fairly dependent on fast-acting yeast. For example, a sourdough baguette or a sourdough ciabatta will not be all that similar to the original.
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