I have been baking sourdough off and on for a couple of years with inconsistent results. The loaf crumb has the appearance and texture of a cellulose sponge, with a crust that is leathery. Also the dough starts off fine but during the fermentation the characteristics change and the dough becomes very soft. Before putting the dough into the oven it has spread rather than risen. There is oven spring which improves the look of the loaf, like a ciabatta.
I was wondering if the two problems were connected, due to the very long fermentation. When baking with commercial yeast with the same hydration and shorter fermentation the loaves are fine.
My recipe is as follows:
White bread flour 1000g
White flour starter 300g @ 150g each flour and water
Taking the flour and water in the starter this makes a dough with 60% hydration.