Sourdough started here at home, fed regularly to fully active but not aged so the last infusion of flour enough to bring sponge to a stiff dough is mostly unaffected. The same degree of sour can be achieved by aging dough made from commercial yeast but its character arising from a single organism would be one-dimensional.
I ran out of a/p flour so substituted Italian 00 flour, the concern is for fineness of milling and not in the protein content as in the U.S.
