Reader Sally had a great question: what’s the difference between “punching down” dough and “gently de-gassing” it as so many artisan bread recipes instruct? Functionally speaking, Sally, there’s not that much difference, both are about releasing built up CO2 and stretching the dough to further distribute the yeast (being buds, yeast don’t move on their own so we have to manually move them if we want to spread them around a bread dough).
That said, the texture of your bread will be different depending on whether you punch your dough or handle it with, er, kid gloves. Punching dough not only deflates large bubbles it breaks them up into lots of smaller ones. After a well-punched dough is baked it tends to have a very tight crumb, which is desirable for sandwich breads, pain de mie and such. Big holes just let sandwich fillings fall through, which is why it’s important to beat sandwich breads mercilessly.
“De-gassing” is what you do for artisan-style breads since the big holes are part of the aesthetic. The idea is to apply only gentle pressure so that the CO2 escapes but the gaps inside the dough are more or less preserved. That’s a good thing since they’ll fill up again with CO2 in the proofing step and bake up to a nice open crumb (i.e. full of holes).