Because of the stiff nature of the Italian style sourdough we encounter a reoccurring difficulty when making lean bread dough. That difficulty being excessive dough strength and the reason for this, is that unlike a wet sourdough culture the activity of protease enzymes is very minimal comparatively. Add to this the tightening effect of gluten by acid (acid makes gluten absorb more water than it would normally) we end up with a very stiff starter that requires a lot of effort to work out when introducing ingredients like water (or fat and sugar) which balance this strength with extensibility. Even when a suitably balanced dough is achieved, likely with very high hydration levels, it only gets stronger as it ferments and proves. Evidence of this can be seen when the dough rises vertically, with splitting occurring in various places.
Biga acida: (12hrs at 18C)
50g lievito madre
Final dough: (2hrs ferment at 30C, 4 hrs proof at 30C)
320g biga acida