Why Does Bread Have Big Holes?
Big holes in bread are usually the result of gas production, dough structure, and how the loaf was handled before baking.
If you have ever cut into a rustic loaf and found an open, airy crumb, the answer often lies in fermentation and gluten development working together in a very specific way.
Those holes are not a defect by default.
In many artisan breads, especially sourdough and high-hydration loaves, they are a sign that the dough trapped carbon dioxide efficiently during fermentation and oven spring.
What causes air pockets in bread?
Air pockets form when yeast or sourdough cultures produce carbon dioxide during fermentation.
That gas gets trapped inside a network of gluten proteins, which stretch like a mesh and hold the bubbles until baking sets the structure.
The size and distribution of those holes depend on several variables working at once:
- Fermentation activity from yeast or wild yeast and lactic acid bacteria
- Gluten strength developed through mixing, folding, and kneading
- Hydration level, or how much water is in the dough
- Proofing time, which affects how much gas is produced before baking
- Handling during shaping, which can preserve or collapse bubbles
When these factors align, bread develops an open crumb with visible holes.
When they do not, the crumb becomes tighter and more uniform.
How fermentation creates holes in bread
Fermentation is the process where yeast consumes sugars in the dough and releases carbon dioxide and alcohol.
In sourdough, lactic acid bacteria also contribute to flavor, acidity, and dough behavior.
The carbon dioxide inflates tiny bubbles throughout the dough, and those bubbles expand as fermentation continues.
During proofing, the dough becomes a living foam.
The gas does not create holes by itself; it creates pressure inside the gluten network.
Once baked, the heat kills the yeast, expands the gas further, and sets the crumb into its final shape.
If fermentation is slow and controlled, the dough can develop larger, more irregular holes.
If it is rushed, the gas may be unevenly distributed, creating a dense loaf with fewer air pockets.
What role does gluten play?
Gluten is the protein structure formed when wheat flour mixes with water.
It gives dough elasticity and strength, which are essential for trapping gas.
Without enough gluten development, the bubbles created during fermentation escape instead of becoming the holes you see in the baked loaf.
Strong gluten helps bread rise in a controlled way, but it does not always mean small holes.
In fact, a well-developed gluten network can support large, irregular air pockets if the dough is handled gently and fermented properly.
Factors that influence gluten strength include:
- Flour type: Bread flour usually has more protein than all-purpose flour
- Mixing intensity: More mixing generally creates a stronger network
- Hydration: Higher water levels make gluten more extensible
- Salt: Salt tightens gluten and slows fermentation
- Autolyse or resting: Resting dough can improve gluten formation naturally
Why do some breads have bigger holes than others?
Not all bread is meant to have the same crumb structure.
A sandwich loaf is designed to be even and sliceable, while ciabatta, baguettes, and sourdough boules often feature a more open crumb.
The recipe, flour, fermentation schedule, and shaping method all influence the final pattern of holes.
Some of the most important differences are:
- High-hydration doughs produce larger, more open holes because extra water allows gluten to stretch more easily
- Long fermentation creates more time for gas accumulation and flavor development
- Minimal shaping preserves large bubbles already present in the dough
- Artisan techniques such as stretch-and-folds support gas retention without fully degassing the dough
Breads with a tight crumb, such as brioche or classic pan bread, are intentionally formulated to reduce large holes.
These loaves often use enriched doughs with butter, sugar, or milk, which change gluten behavior and create a finer texture.
Does shaping affect the size of bread holes?
Yes, shaping has a major effect on crumb structure.
If dough is handled aggressively, many of the gas bubbles formed during fermentation are pushed out.
That creates a tighter crumb.
If shaping is gentle and intentional, larger bubbles remain in place and expand in the oven.
Professional bakers often aim for surface tension during shaping.
This means pulling the outer layer of dough into a smooth, taut shape while trying not to burst too many internal bubbles.
The result is a loaf that rises upward and preserves irregular holes inside.
For breads with very large holes, such as some sourdough loaves, bakers often avoid overworking the dough.
Excessive degassing can reduce the open structure that makes these breads distinctive.
How hydration changes bread structure
Hydration refers to the ratio of water to flour in a dough.
Higher hydration doughs are stickier, softer, and more extensible.
Because the dough is looser, gas bubbles can expand more easily before the gluten sets.
This is one reason ciabatta and rustic sourdough often have dramatic holes.
The dough contains enough water to encourage an airy structure, but it also requires careful handling to prevent collapse.
Lower hydration doughs, such as bagels or many sandwich breads, usually produce a more compact crumb.
Less water means a stiffer dough, which limits bubble expansion and results in smaller, more uniform holes.
Can proofing create too many large holes?
Yes.
Overproofing can lead to uneven or excessively large holes, especially near the top of the loaf.
When dough ferments too long, the gluten may weaken and gas cells may merge or collapse.
The final bread can look airy in some areas and dense in others.
Signs of overproofing include:
- Dough that feels fragile or overly slack
- Excessive spreading after shaping
- Large irregular tunnels near the crust
- A loaf that deflates when scored or moved
Underproofing can also produce strange hole patterns.
If the dough has not fermented enough, the crumb may contain random tunnels or dense patches because the gas has not had enough time to distribute evenly.
Is bread with big holes always good?
Not necessarily.
Large holes can be desirable in rustic bread, but they are not always ideal for every use.
For sandwiches, toast, and spreads like peanut butter or jam, a more even crumb is often more practical.
Very large holes can make slices less sturdy and allow toppings to fall through.
In artisan baking, the goal is usually a balanced structure: open enough for lightness and texture, but stable enough to slice cleanly.
The best crumb is the one that matches the bread’s intended purpose.
How to tell whether big holes are normal or a problem
Large holes are normal when they match the style of bread you baked or bought.
In sourdough, ciabatta, and long-fermented lean doughs, uneven holes are expected.
In enriched breads or pan loaves, large voids may indicate shaping issues, poor degassing, or uneven fermentation.
Ask these questions when evaluating the crumb:
- Was the dough high hydration?
- Was it fermented for a long time?
- Was the shaping gentle or aggressive?
- Was the loaf baked in a pan or freeform?
- Does the bread style normally have an open crumb?
If the answer to most of these points points toward artisan baking, the holes are likely part of the intended texture rather than a flaw.
Why does bread have big holes in sourdough specifically?
Sourdough often has big holes because its fermentation is slower and more complex than commercial yeast bread.
The combination of wild yeast and lactic acid bacteria produces steady gas, acidity, and flavor over a longer period.
That extended timeline gives the dough more opportunity to build an open crumb.
Sourdough bakers also tend to use higher hydration, long bulk fermentation, and gentle folding techniques.
Those methods all encourage large, irregular air pockets.
The result is the chewy, open texture many people associate with handcrafted sourdough bread.
What baking methods encourage an open crumb?
Several techniques can encourage big holes in bread while preserving structure:
- Use strong bread flour for better gas retention
- Increase hydration gradually to make the dough more extensible
- Develop gluten with folds instead of overmixing
- Allow adequate bulk fermentation for gas production
- Shape gently to preserve internal bubbles
- Bake with steam to support oven spring and crust development
These methods are especially effective in hearth breads and sourdough formulas.
They are less suitable for breads meant to have a close, even crumb.
Why does bread have big holes after baking?
Once dough enters the oven, heat causes several changes at once.
Gas inside the dough expands, yeast activity briefly accelerates, and the gluten network begins to firm up.
This stage, known as oven spring, can enlarge existing bubbles and freeze them into place as the crumb sets.
That is why the holes you see in finished bread are often larger than the bubbles that existed before baking.
The oven amplifies the structure created during fermentation and shaping.
Understanding why bread has big holes comes down to the interaction between biology, chemistry, and technique.
Fermentation makes the gas, gluten holds it, hydration shapes it, and baking locks it in.
