How Do You Know if Your Bread is Over-proofed?

To say that a bread is over-proofed means that it was allowed to rise long enough that the gluten was no longer sufficient to sustain the structure of the loaf. The bottom of the loaf will be much denser than the top (as the weight of the loaf has sort of compressed it.) An indication that a loaf is overproofed is that it falls or collapses in the oven while baking.

Tests:

• The most common method is 'finger poking.' Take (the pad of) your index finger and indent the loaf about 1/2 inch. If the indentation rises back immediately, the dough is underproofed. If it springs back somewhat, but still leaves an indentation, it's probably fully proofed. BUT, if the imprint remains without springing back, the dough is overproofed.
• If you score your loaf and it significantly deflates, it's definitely overproofed. IMO better always slightly underproofed than at all overproofed.

What to Do?

• Reshape and let it rise again. Depending on how much "oomph" the yeast has left, it should work just fine. If it doesn't rise add 1/4 teaspoon of sugar and yeast to it, and knead it again. cover and let proof.
• Use the overproofed dough as a preferment. Make a second batch of the same proportions, and mix the old dough (cut in pieces) into it. Do it at the beginning of the mixing process, the way you would do it with a biga. Then proceed with the new, double batch as usual. You will have better gluten and more taste than if you used no preferment.
• Use for pizza crust.