Is it true that you can test yeast bread for doneness by tapping the loaf and seeing if it sounds hollow? How do I know when my bread is done?
Long before cooks had handy tools such as instant-read thermometers to aid in determining doneness, tapping the bottom of bread was one way to assess its readiness for the cutting board. Still, the technique requires a practiced ear and not everybody embraces its utility. (Marion Cunningham in The Fannie Farmer Cookbook, for one, warns that bread “often” sounds hollow—even when it’s not done.) We baked our multigrain and American sandwich breads and then tapped the bottom crusts with our fingertips when they were below, at, and above their target temperatures (200 and 195 degrees, respectively). Some of our testers had no trouble recognizing the hollow sound of a fully cooked loaf, but to others, a tap on an underdone loaf sounded virtually the same. With practice, we might become adept at detecting when a tap sounds hollow; in the meantime, we’ll stick to testing bread with our instant-read thermometer.
We commonly advise checking the internal temperature of a loaf of bread before making the decision to pull it from the oven. A properly baked loaf should register a temperature between 195 and 210 degrees on an instant-read thermometer, depending upon the type of bread. But is internal temperature by itself sufficient proof that bread is fully baked?
We placed temperature probes in the center of two loaves of rustic Italian bread and monitored them as they baked. Halfway into the baking time, the internal temperature of the loaves had already passed 200 degrees, and they reached the optimal 210 degrees a full 15 minutes before the end of the recommended baking time. We pulled one loaf from the oven as soon as it neared 210 degrees and left the other in the oven for the recommended baking time. (The temperature of the longer-baked loaf never rose above 210, because the moisture it contains, even when fully baked, prevents it from going past the boiling point of water, or 212 degrees.) The differences between the two loaves were dramatic: The loaf removed early had a pale, soft crust and a gummy interior, while the loaf that baked the full hour had a nicely browned, crisp crust and a perfectly baked crumb.
The takeaway? Internal temperature is less useful than appearance as a sign of a well-baked loaf. We found that bread can reach the optimal temperature for doneness—210 degrees for the rustic Italian bread above—well before the loaf is actually baked through. You can take the temperature of your bread, but stick to the recommended baking time and make sure the crust has achieved the appropriate color before removing the loaf from the oven.