Crumb

The crumb is the inside of a baked loaf or cake, everything under the crust. Bakers describe it by the size and spread of its holes and by how it feels: open or tight, soft or chewy, moist or dry. Looking at the crumb is the best way to check how a bake went. The word also means small bits of bread, as in breadcrumbs, and the crumbly topping on a streusel cake.

How to tell it is done

Cut a loaf only once it has cooled for at least an hour, or the crumb looks gummy. Then look at a slice:

• Open crumb: big, uneven holes with shiny walls. Typical of ciabatta and high hydration sourdough.
• Tight or closed crumb: small, even holes. Typical of sandwich bread, brioche and most cakes.
• Gummy crumb: damp and sticky, often near the base. The bread was underbaked or cut too soon.
• Dense crumb with a few big holes near the top: the dough was under-fermented.
• Very large holes with thin, torn walls, and a flat loaf: the dough was over-proofed.

Why it works

Gas from yeast or leavening forms bubbles in the dough or batter. Gluten in bread, or egg and starch in cake, holds those bubbles. In the oven the bubbles grow and then the walls set. More water, longer fermentation and gentle shaping keep bubbles large. Kneading, a lot of fat or sugar, and tight shaping keep them small.

Common mistakes

• Chasing big holes in every bread. A tight crumb is right for toast and sandwiches.
• Judging the crumb from a warm loaf. Starch is still setting, and the inside looks wetter than it is.
• Deflating the dough hard at shaping when you want an open crumb.

In recipes

"A tender crumb" in cake recipes means soft and fine, often from creaming, buttermilk or cake flour. "A moist crumb" is the same idea. "Crumb shot" is a photo of a cut loaf that bakers share to compare results. "Crumbs" alone in an ingredient list means breadcrumbs.