I look at a biga as something a lot like a sponge, as in a sponge-dough process. You can ferment as much or as little of the flour as you wish, but as you ferment lass of the flour, the flavor of the finished crust dimenishes, so fo rthis rreason, I like to use from 60 to 80% of the total flour in the sponge, with the remainder of the flour going into the dough side.
The sponge is made from only flour, water and yeast.
Here is an example, using 50-pounds of total flour weight.
80/20 sponge-dough system
Sponge:
Flour: 40-pounds
Yeast: 4-ounces (IDY)
Water: 20-pounds (70F)
Mix together at low speed for 6-minutes, then set aside and allow to ferment for 3 to 4 hours at room temperature.
Optional: Reduce the yeast to only 1-ounce and place the sponge into the cooler after mixing to ferment over night.
Add the following to the mixing bowl:
Dough side:
Flour: 10-pounds
Salt: 14-ounces
Olive oil: 1-pound
Water: 8-pounds (75F)
Mix together for 2-minutes at low speed, then add the fermented sponge and mix just until the dough takes on a smooth, satiny appearance (about 6 minutes).
Optional:
If you put the sponge in the cooler over night, increase the water temperature at the dough side to 85F, then add 4 more ounces of IDY, and mix to a smooth, satiny appearance as described above.
You can really develop some great flavored crusts using this method, especially when you allow the dough to ferment in the cooler over night.
Tom Lehmann/The Dough Doctor