My bread recipe (from Artisan Bread in Five Minutes a Day) calls for waiting for the dough to double, then "fall." It never falls, though I cover the dough as instructed (not airtight) either with a towel or plastic wrap sprayed with cooking spray. I have tried spraying the bowl with cooking spray, and have tried without. Neither results in a "fall."
I've tried using a wide stainless steel bowl as well as one of those food-grade rectangular plastic storage containers a la Alton Brown.
Is the "fall" important? If so, what can I do besides slam the bowl to coax the dough to fall as instructed?
Best Answer
Basic Physics of the System
Bread rises (as you probably know) due to microorganisms, primarily yeast, converting sugars into CO₂ + byproducts. The CO₂ forms bubbles, stretching the gluten in the flour. In order for the bread to rise, the microorganisms must produce CO₂ faster than it can escape from the dough.
Graphed over time, the amount of CO₂ produced would start at 0, fairly quickly rise to its maximum (as the yeast, etc. come back from dormancy), then slowly decrease, eventually to 0 (as they run out of food and/or are overwhelmed by byproducts such as alcohol). The amount of gas escaping from the dough also changes over time. It must obviously start at 0, and probably increases over time (after all, there is more to escape), and eventually of course its all escaped and thus it must be 0 again, but I'm not sure of its exact shape. So, a diagram:
That's the basic physics of the system. At some point, the bread must fall. (Well, maybe in a 0-g environment it would shrink instead of fall, but…)
How the Environment Matters
The microorganisms are very sensitive to fairly small changes in their environment. In particular:
Also, generally speaking, slower leads to better flavor. So its not a bad thing.
Summary
Give it longer. Provided you've covered it in plastic (so it doesn't dry out), it'll eventually fall.
Keep in mind that "fall" doesn't mean it'll return to its original size, just that it'll fall back from its maximum size. The "or flattens on top" comment in your book is a pretty accurate description of what it looks like. Normally, while its rising, there is a dome shape on top, with the center as the highest point. When it starts falling, that dome vanishes, and may even invert (as in, the center will be the lowest point).
I've made preferments that take upwards of 20 hours to fall. It will eventually happen. And when it takes forever, it'll probably taste better.