Mega Tunnel in a basic sandwich loaf

Next time:

Make sure that before you shape the loaves that you gently de-gas (remove the bubbles) from them.

Make sure that you shape the bread fairly tightly. Don't use too much flour during the shaping process: it can keep the dough in the middle of the loaf from adhering properly, particularly if you roll the loaf for a pan loaf.

Sometime you get these "baker's attics" when the loaves are overproofed, but I think it's more likely that you need to tweak your de-gas and shaping technique a bit.

Those loaves look pretty good, by the way.

Usually these things happen, when the dough is UNDERprooved or the enzymatic activity is high (or not enough sour).

As your bread has this mushroom head it had a quite good oven spring - a sign of underproofing. Breads in loafpans I try to bake without much ovenspring. (Just from expanding the gas that already existst but without producing much new one).

How did you shape the dough parts before putting them into the pan?

Adrian

When making sandwich loaves, it is usually a good idea to keep the hydration on the low end. For myself, anywhere from 60% to 67% is fine.

Second, use as little flour as you can get away with on the shaping board; you need the dough to have some friction/drag  while shaping. Be free with your bench scraper to free sticking dough. I sprinkle a little flour on the board and rub it in. You shouldn't be adding flour to the dough through your shaping. I also like to use a wood kneading/shaping board. A ³⁄₁₆" thick birch-faced plywood works well.

Third, the de-gassing isn't about removing the air from the dough, it's about making bunches of small bubbles from the large bubbles. Spread the dough, good side down on the board. Use the palm of your hand to slap the dough down. That won't expel a lot of gas, but will break up the bubbles.

For bastard loaves, the preshape is a ball. Fold opposite side together and pinch closed, then do the same to the corners. Once relaxed, break up the bubbles again and shape by doing a letter fold. On each fold, use your finger tips to pinch the edge to seal, then use the heel of your hand to press toward the folded edge, pushing the air into the loaf. After the two folds, fold in half lengthwise and seal the seam with the heel of the hand. Tighten and let rise.

I give you my method because it appears to me that your problem is shaping related, and over the last few years, except for one thing or another, my go-to bread is a sandwich loaf, in a range of hydrations, with or without a range of 5-30% rye or whole wheat. The method I've outlined provides me a light fluffy loaf with small, evenly spaced alveoli.

cheers,

gary