Please help. Any suggestions would be appreciated.
We've been having this problem, having big holes in sourdough, for a while now. This problem seems to occur only in plain sourdough, but not any other type of sourdough (i.e. wholemeal sourdough, sourdough with grains or any other added ingredients.). Often crumb seems to come off the crust on the bottom as you can see from the picture. Not every loaf is like this or as bad as this but we quite often find loaves similar to this (usually, the size of the hole is about a half of what you can see in the picture).
We feed our culture with unbleached flour from Wholegrain Milling (NSW Australia). We use both liquid and stiff leaven. We mix the dough in the morning, then rest it for a few hours, scale, rest, shape, retard overnight and then bake off the next morning.
We've tried a few things to solve this issue. We've tried changing the amount of gluten, hydration, humidity/temperature of retarder-prover, oven temperature and shaping method but none of them has worked out. I'm running out of the solutions.
Has anybody had the same or similar problem to this before? Please give me some ideas to solve this problem...