I found the discussion of factors affecting sourness in sourdoughs (by Mike
Avery in bread-bakers.v103.n039.5) to be quite interesting. It makes sense
to me that by cooling the rise you'd favor one type of bacterial process
over another, but I was surprised by two points: thick=sour, thin=mild.
Most of the sourdough recipes I've read call for thin, pancake-batter-type
starters for quite sour San Francisco or Alaska sourdoughs, and thick,
doughy starters for mild, rustic european levain-type breads. Is the
thick/thin issue mostpertinent for the starter's texture while being
fed/maintained between bakings, or while being fed/expanded for the next
baking, or at all times?
I was also surprised to see ash content making an impact; is this a lesser
factor than texture and temperature? I've made very sour and quite mild
breads with both whole grain and white flours, but never compared them head
to head.
Diane Brown in St. Louis