oven spring - question for the sourdough sages
As there seems to be more than a little Zen to soudough baking, I though sourdough sages was a more appropriate term than sourdough experts. Anyhow, here is my question, or rather more of an observation. Whenever I cook a loaf where the levening is with sourdough culture alone, the rise is always less, both during the fermentation and proofing stage, although I always get much better oven spring compared with yeasted loaves. I appreciate that fermentation takes much longer with the starter than with dried yeast, and perhaps I get a little impatient and limit the proof to 1 hour when two may be better. But the substantial oven spring suggest the dough has been proofed enough. Is the greater oven spring due to more substantial gluten development with sourdough in general? normally I do not kneed but develop gluten through and autolyze followed by multiple stretch and folds.
I have to preface this by saying I'm more of a Sourdough Rye baker than a sourdough sage, but I do like that term and you bet I'll start using it too!
In sourdough breads that use high-protein flours like rye, one does not expect the same kind of gluten development nor see the kind of springs that other levains can achieve-- so I can assume you're not using them!
It sounds like you're not allowing your loaves to fully proof before baking, which although not disastrous, is a little unorthodox (and, I should mention, this problem is not endemic to sourdoughs--just seems to be brought on by the sourdough process you're using). What's causing your extra spring is an uneven distribution of yeast-fermentation activity. When a bread fully proofs, all the yeast in distributed throughout the bread has had equal access to both food and energy (being heat). When you bake a bread before it has fully risen, the yeast closer to the exterior of the crumb gets treated a little bit better: it has more food to eat than in a normally-proofed bread and it also has more energy to consume it than normal (because of the heat).
What you end up with is a non-uniformly developed crumb, which can have both visual and palatable differences from normally-proofed bread. This is most noticeable if you're trying to be perfect and bake the best possible bread you can... but that's maybe not what we at-home bakers try to do. If you and the people you bake for like your bread the way you're doing it now, maybe tweaking your method is only inconveniencing you with marginally perceptible gains.
Hope this helps--but you might want to wait around for some sage advice too (I'm interested to hear what they have to say!)
From what you've posted you're doing fine. It's better to get a good oven spring than risk the loaf spreading too much before going into the oven. Would like to see a crumb shot if possible.
Jim