I have really gotten attached to using a poolish as the starter for sourdough bread. Using a poolish is really easy. You just mix flour, water and starter, and set it aside to ferment for 12 hrs. It is technically called a preferment.
There are disagreements between the definitions of poolish, biga and a sponge. It seems like the poolish is 100% hydration, or 1:1 flour:water. The biga is 1:0.7 flour:water, and a sponge is 1:0.4 flour:water.
I have tried a couple of poolish recipies from John Kirkwood. The one I am using now is from Sourdough Bread made in a dutch oven, Part 2 of 2 My small convection oven is large enough for a small dutch oven. Because the oven is small, it can heat up faster than my large oven. Unfortunately the small dutch oven cannot hold all the dough of the recipe, so I split the dough into two, doing two breads instead. It has worked out quite well for experimentation, but I’d rather have to loaves that are a bit larger. This means scaling the recipe up by 50%.
John Kirkwood’s sourdough recipe that uses a poolish.
Scaling the recipe has a couple of options, but I’d rather just scale everything with identical proportions. This means understanding the math behind the recipe and respecting the proportions. The preferment should be from 25-30%.
We know the ratios of each type of preferment, but how do you get the ingredient amounts for the preferment from the original dough? Start with the flour. A good range for the weight of the preferment flour is 20 to 30% of the total weight of flour in the recipe source
The original recipe has flour 610g and water 380g, total 990g. The hydration is 380/610 = 62%. The recipe is not too wet and therefore relatively easy to work with. The poolish, in total, is 300g, 300/990, or 30%. Total flour = 100g (poolish) + 50g (starter) + 460g (recipe) = 610g. Total water = 100g (poolish) + 50g (starter) + 230g (recipe) = 380g
Poolish (original recipe)
-100g white flour
-100g water (no chlorine, tepid)
-100g starter (50% flour, 50% water)
Bread recipe (original)
-460g white flour
-230g water (no chlorine, tepid)
-1 tbsp oil
-1 tsp salt (8g)
Scaling up the recipe 50% means the total weight is 990 *1.5 =1485g, flour 915g, water 570g. A 30% poolish would be 445.5g, or roughly 150g flour:150g water:150g starter. The hydration remains the same at 62%. The new recipe is now:
Poolish (scaled 50% recipe)
-150g white flour
-150g water (no chlorine, tepid)
-150g starter (50% flour, 50% water)
Bread recipe (scaled 50%)
-690g white flour
-345g water (no chlorine, tepid)
-1 tbsp oil
-1 tsp salt (8g)
I have tried 20% whole wheat 80% white flour, and this has turned out quite well, but is less wet than using 100% white flour. I might try bumping up total water by 10% and see the result.
For the final bulk fermentation I have used oiled bowls, which I then put sesame seeds and poppy seeds. This has then stuck to the dough and have turned out quite well.
While I am satisfied with the crumb and big enough air holes, the oven spring is lacking. This seems to be a visual issue, certainly not a problem with taste or texture, but it would be nice to be able to also get good oven spring. Maybe it is my starter, so I am trying to improve this.
Of course all bread making is endless experimentation. I have a long way to go before completely satisfied with the end result. At least there’s a lot of fun in eating your end product.