keeping dough structure for long proofs
Hi I'd be grateful for some advice. I have been baking for about a year, and mostly variations on a single recipe:
250g levain (whole wheat flour, original starter just rye)
1000g wheat flour (30-40% whole grain)
700-750g water. (dry enough that even when just mixed, it doesn't completely flatten out)
17 g salt.
After mixing the ingreidients, I do 4-5 stretch and folds over the next few hours and shape after 4-6 hours (depending on toom temperature), then final proofing of 8-12 hours (again, depending on room temperature).
Don't get me wrong, I like my bread, quite a lot in fact.But over the last few months I have noticed some small changes:
1) My dough really turns into mush by the time it is ready to bake. It has not only started to deflate, but when I pop it in the dutch oven, it collapses and there isn't much rise at all. Scores don't open up at all sometimes.
2) For all that proofing, the sourdough flavor is not quite as strong as it was some months ago, and it seems to me a bit more one sided (more acetic, less lactic acid perhaps?).
I'd like to be able to achieve the right flavor without my dough deteriorating to quite the degree that it does. I have tried doing a more vigorous knead just before shaping, didn't help. Wondering if anyone has any suggestions.
PS I am in Germany, using whole grain and "550" flour.