Crumb Clues: How to Read and Debug Your Bread

A Practical Guide to Diagnosing Fermentation, Dough Strength and Bake

by Hendrik Kleinwächter

What crumb means

Crumb is the interior of the loaf, the web of set starch and gluten that holds gas cells, the alveoli. A tight crumb has small, evenly spaced holes. An open crumb has larger, irregular holes. Neither is better in isolation. Fit the crumb to your goal. A delicate honeycomb crumb gives lift and tenderness without losing your jam to the plate. A very open country loaf makes a beautiful showpiece, but it is less practical for sandwiches.

The honeycomb crumb, a sign of balanced fermentation

Look for: a crisp crust, lively vertical spring and evenly distributed alveoli with no giant voids. The crumb feels light and fluffy, not dry or custardy.

What it means: Fermentation was well-timed. Flavor is balanced. Expect gentle lactic or lightly vinegary notes depending on your starter.

How to get it: Handle the dough as little as possible after bulk to avoid needless degassing. If you are baking a single loaf, consider skipping pre-shaping. If you are baking several loaves, a brief pre-shape helps organize the dough, and slight merging of larger pockets during shaping supports that honeycomb pattern. Nail fermentation cues, not the clock.

Overfermented crumb

Look for: a low-profile loaf with weak or no oven spring, many tiny uniform bubbles and a gummy or fragile texture. The dough may have felt slack and tear prone, or overly sticky, before baking.

What it means: The gluten network was over-weakened by enzymes and bacterial proteolysis. It could not trap gas, so the structure collapsed. Flavor skews sharply sour.

How to fix it:

• Stop bulk earlier. Track rise with an aliquot jar. Start by ending bulk at about a 25-percent volume increase, then calibrate toward 50 to 100-percent based on flour strength and temperature.
• Strengthen the leavening side of your starter. Feed more frequently, use higher refresh ratios like 1:5:5 or 1:10:10, or keep a stiffer starter to dial back bacterial vigor while supporting yeast.
• Reduce warmth or time in bulk and proof. Shorten or cool the cold retard if you use one.

Underfermented crumb

Look for: very large, uneven pockets or craters, with undercooked, gummy patches. You may still get a dramatic ear from scoring, the fool’s crumb that suggests success from the outside while the interior lags behind.

What it means: Fermentation did not produce enough gas to inflate the gluten network uniformly. Heat transfer was uneven, so parts of the interior set late. Flavor reads pale and neutral.

How to fix it:

• Ferment longer, or a little warmer. Increase inoculation or use a livelier starter; for example, daily refreshments at 1:5:5, or a stiff starter that favors yeast activity and slightly lowers acidity.
• As a planning anchor, many lean doughs finish bulk in 8 to 12 hours at cool room temperature. Your flour and climate will shift this window, so watch the dough. Look for gentle puffiness, a rounded rather than flat edge in the bowl and a soft, jiggly feel when you shake the container.

Other crumb trouble signals

Insufficient dough strength

Look for: a loaf that spreads sideways with limited upward spring, a squat profile and uneven cell size.

Why it happens: Gluten was underdeveloped, or it relaxed due to overproofing.

Fix: Mix or knead a bit more at the start, reduce hydration for a more elastic dough, add one or two extra sets of stretch and folds during bulk, and shape more tightly.

Baked too hot or with too little steam

Look for: Crust sets early, large holes collect under the crust, crumb feels less fluffy than expected.

Why it happens: Without steam, or at excessive heat, the skin hardens before the loaf can expand.

Fix: Aim for about 230 °C or 446 °F for strong oven spring. Supply ample steam for the first part of the bake. In a Dutch oven, preheat thoroughly and keep the lid on for the initial stage so the loaf can expand before the crust firms.

A simple crumb reading workflow

1. Slice and scan. Note overall height, symmetry and distribution of holes.
2. Pinpoint the pattern. Many tiny bubbles suggest overfermentation. Giant caverns and gummy streaks suggest underfermentation. Side spread points to low strength. Holes clustering near the top crust signal early crust set.
3. Taste for confirmation. Sharp tang and a sticky bite point to overfermentation. Bland flavor and doughy patches point to underfermentation.
4. Adjust one variable next time: earlier or later bulk, warmer or cooler dough, stronger or gentler handling, more or less steam. Change only one thing so you can learn from the result.

Pro tips that pay off

• Use an aliquot jar. Save a small piece of dough at the start of bulk in a straight sided jar. Mark the level. When that sample reaches your chosen rise target, move to the next step for the main dough.
• Feed for function. Higher refresh ratios and, if you like, a stiffer starter encourage yeast-forward activity and keep acidity in check, which supports structure and spring.
• Handle with intent. Every touch moves gas. During shaping, keep tension where you want lift. Avoid crushing pockets that contribute to a light honeycomb.
• Bake for expansion first, color second. Steam early, then vent or uncover to finish the crust.

The takeaway

Your crumb is a conversation among fermentation, strength, and bake. Read the signs, link them to taste and feel, and then make one targeted adjustment. Do that and your next loaf will not only look better; it will eat better.

(This article appeared in the Fall 2025 issue of Pastry Arts Magazine)