I used to make a 100% whole wheat sandwich bread from a white flour recipe I adapted. It had a low hydration, and was prepared in the classical mix-knead-rise-shape-rise-bake. Sometimes I would add other grains to this basic recipe. My loaves were rather dense, and often they would not rise very much. I think I may have overworked the dough in an effort to get that elusive window pane. BUT they tasted great!

Then I learned about whole wheat and hydration, plus a few "new" tricks that I thought would help me get bigger, lighter loaves. So recently I've been baking 100% whole wheat at 70-75% hydration, doing an autolyse, and using the refrigerator for 18 hour ferments with about 3 stretch and fold sessions thrown in. My loaves came out much higher and lighter. BUT I noticed 2 things: first, a very noticeable bitter taste which I never had before, and secondly, a "crumbly" crumb that would barely hold a slice of bread together.

Can anyone help me explain this? I might mention also that my original recipe called for 2 tbsp of instant yeast. I reduced this to 1 1/2 tbsp in view of the long ferment, but maybe it was still too much? Because the dough would still rise rather fast even in the fridge, and each time I did a stretch and fold I'd have to de-gas the dough so it might have risen too many times.