In past columns we've discussed how to mix and knead the dough for yeast bread. After being prepared, the dough is covered and left in a warm, draft-free place until it doubles in volume.
During this proofing, or fermentation period, the yeast cells feed on sugar and produce carbon dioxide. It's this gas that lightens the dough and makes it expand.
The dough should not, however, be allowed to more than double or it may collapse back into the bowl. Bread baked from dough that is overproofed has a tendency to be coarse and dry.
To check whether it is ready for shaping, lightly press a finger one-half inch down into the dough. If the indentation remains when the finger is removed (Step 1), the dough has doubled and is ready for the next step.