Bulk fermentation is done when a dough is strong enough to remember its shape after baking.
Don't all breads remember their shape after baking?
Syntactical ambiguity is what Chomsky would say! Are synthetic buffalo hides about fake bison or faux skins? The above sentence means, bulk fermentation is finished when a dough can remember whatever shape it is supposed to have after baking is complete; i.e., when a dough can be formed into whatever shape it is to have as bread (after baking) and maintain that form until it is bread, then bulk fermentation is done.
This is the simplest answer I could come up with to your question, and also the most complete.
Can I assume that you mean bulk fermentation is done when the gluten matrix develops to the point that the it will not break down and will "remember" or spring back into shape in presence of high heat despite gravity or other disturbances? That's not quite as simple as the finger poke test, but interesting nevertheless. Thanks for your answer. -Varda
The finger-poke test has nothing to do with measuring bulk-fermentation, and, in fact, is traditionally used to gauge a dough while in its final throes of fermentative stage where it needs to be transferred to an oven, the gray area where log-phase has turned to lag.
I thought long about your question. I arrived at a number of complicated conclusions. I simplified those conclusions, distilling them as much as I could, and then I tried to summarise those into one, simple sentence. I will let you untangle the implications, but I think this is the simplest and most accurate way for a home-baker to judge when bulk-fermentation is done. There is a bit of "flex" room, too, as everybody has a different end-product in mind.
The finger-poke test has nothing to do with measuring bulk-fermentation, and, in fact, is traditionally used to gauge a dough while in its final throes of fermentative stage where it needs to be transferred to an oven
Yes, I understand that. I was making an analogy. But no matter. I appreciate your answer. -Varda
Sorry, please understand I often take things quite literally (see my introduction).
Text only communication can be difficult. And really your answer is quite excellent, and one of the most interesting thing I've heard anyone say on the matter. -Varda
Notice that what I wrote says nothing about the true insides of bread, the flavour, and that's the most important consideration for me.
You were giving a structural answer to the question of when bulk fermentation is done and time to move to fermentation of shaped loaves. So as you are putting it, the answer is not a matter of flavor. The gluten forms a matrix with crosslinks between gluten chains and when that matrix reaches a certain point of development (when the dough will remember its shape with heat applied) that's when BF is done. The flavor is more of a matter of all the life processes that are taking place in this little developing world. Or at least I think that's what you are saying.