In yeasted dough recipes, fermentation is a key step in building flavor. Here's how it works.
In yeasted dough recipes like our Thick-Crust Sicilian-Style Pizza (see related content), fermentation is a key step that occurs after the dough has been mixed and kneaded. In this stage, the yeast consumes sugars in the dough, producing not only carbon dioxide, which is critical to give the dough the proper rise, but also numerous flavor and aroma molecules. The typical bread recipe calls for fermenting the dough on the counter. But we often let the dough ferment in the refrigerator—usually for at least 24 to 48 hours and sometimes up to 72 hours—because we’ve found that we get more flavorful results.
Here’s why: Yeast left out at room temperature consumes sugars and leavens the batter rapidly. But then it’s spent; it stops producing not just gas but also compounds that give bread flavor. At cool temperatures, yeast produces carbon dioxide more slowly, so refrigerating the batter allows yeast to leaven at a slow and steady pace, providing more time for a more complex-tasting combination of flavor compounds to develop. The net result? A more flavorful dough.
To demonstrate how temperature affects the rate of carbon dioxide production in dough, we prepared a yeasted batter (its more fluid consistency would be easier to use with our testing equipment) and split it into two batches. We placed each in a simple device we fashioned from a test tube and a semipermeable balloon to capture gas. We left one out at room temperature and placed the other in the refrigerator and then monitored the gas production of each at various intervals.
The yeast in the room-temperature batter produced enough gas to fill the balloon within 3 hours but then was spent, while the refrigerated batter continued to generate just enough gas to keep the balloon partially filled even after 18 hours.