What You’ll Learn
- What bulk fermentation is and when it begins.
- Why temperature matters more than recipe timing.
- How much rise to look for before shaping.
- The signs of under-fermented and over-fermented dough.
- How folds, flour and starter strength affect the process.
Quick Answer
Bulk fermentation is the main fermentation stage after the starter is mixed into the dough and before final shaping. It is complete when the dough has gained strength, developed visible bubbles, become lighter and increased by an appropriate amount for its temperature and recipe.
Do not wait automatically for the dough to double. In warm conditions, a smaller rise may be enough because fermentation continues during shaping and final proofing.
Bulk fermentation is where much of the loaf’s structure, flavour and gas development takes place. It is also the stage beginners find hardest to judge because recipes often give a number of hours without fully explaining the signs.
The clock can tell you how long the dough has been fermenting. It cannot tell you how far fermentation has progressed.
Baker’s Vocabulary
Bulk Fermentation
The first main fermentation of the complete dough. It starts when the starter is incorporated and ends when the dough is divided or shaped.
When Does Bulk Fermentation Begin?
For practical home baking, bulk fermentation begins when the active starter is mixed into the dough. Salt may be added immediately or shortly afterwards, depending on the method.
Stretch-and-fold or coil-fold sessions happen during bulk fermentation. They do not restart the clock.
Why Dough Temperature Matters
Warm dough ferments faster. Cool dough ferments more slowly. This sounds simple, but it explains why identical recipes can finish several hours apart in different kitchens.
Measure the dough temperature after mixing. This gives you better context than room temperature alone because flour, water and the mixing bowl all affect the final dough temperature.
The Science Behind It
Yeast and bacteria metabolise more quickly as temperature rises within a suitable range. This increases gas production and acid development. Temperature therefore changes both the speed and character of fermentation.
From Our Workshop
Many dense beginner loaves are not caused by poor shaping or scoring. The dough simply reached the shaping stage before bulk fermentation had developed enough gas and strength.
The opposite happens in hot weather: bakers follow a winter timetable and the dough ferments too far before they notice.
The Main Signs Bulk Fermentation Is Progressing
What You’ll See
- The dough gains volume.
- Bubbles form along the sides and surface.
- The top becomes smoother and slightly domed.
- The dough jiggles when the container is moved.
- The texture becomes lighter and more aerated.
- The edges look rounded rather than dense and flat.
- The dough stretches with more strength.
- Small fermentation bubbles may appear beneath the surface.
How Much Should the Dough Rise?
There is no single percentage that suits every recipe and temperature. A warm dough generally needs a smaller rise before shaping because fermentation continues rapidly afterwards. A cooler dough may need a larger rise during bulk.
| Dough condition | General approach |
|---|---|
| Warm and moving quickly | Shape after a more modest rise and clear aeration |
| Moderate temperature | Look for a balanced rise, bubbles and improved strength |
| Cool and moving slowly | Allow more time and potentially a greater rise |
| Very weak starter | Fix starter strength rather than extending bulk indefinitely |
These are principles, not exact targets. Learn to combine volume with texture, bubbles and temperature.
What Do Stretch and Folds Do?
Folds strengthen the developing gluten network, redistribute temperature and move microorganisms towards fresh food. They also help the dough hold the gas produced during fermentation.
Most folds are completed during the earlier part of bulk fermentation. Later handling should become gentler so you do not repeatedly knock out the gas you are trying to preserve.
Common Mistake
Do not continue folding simply because the dough is still in bulk fermentation. Excessive late handling can tighten or degas the dough. Folds are a strengthening tool, not a ritual that must continue until shaping.
Signs of Under-Fermented Dough
- Little visible rise
- Few bubbles
- Dense, tight texture
- Dough tears rather than stretching
- Loaf feels heavy after baking
- Tight or gummy crumb
- Large isolated tunnels surrounded by dense crumb
Signs of Over-Fermented Dough
- Dough becomes very loose and fragile
- Surface loses strength
- It spreads rapidly after turning out
- Shaping tension is difficult to create
- Dough feels excessively sticky despite earlier strength
- Finished loaf has poor oven spring
- Crumb may be weak, compressed or irregular
Ready to Shape
- Noticeable rise
- Bubbles throughout
- Rounded edges
- Light jiggle
- Improved elasticity
- Aerated texture
Needs Reassessment
- No visible development
- Very dense texture
- Severe spreading
- Collapsed structure
- Strong tearing
- Fermentation far beyond plan
A Practical Bulk Fermentation Workflow
From Mixing to Shaping
1. Mix and Record
Record the time and dough temperature when the starter is incorporated.
2. Build Strength
Complete the planned folds during the early part of bulk fermentation.
3. Leave It Alone
Allow the dough to ferment undisturbed while observing rise and bubbles.
4. Assess the Dough
Combine temperature, rise, aeration, strength and jiggle before deciding.
5. Pre-Shape and Shape
Move on while the dough still has enough strength to hold tension.
Bake Slower Tip
Use a straight-sided container and mark the starting level. Guessing volume in a wide bowl is much harder than measuring visible rise.
Frequently Asked Questions
Does bulk fermentation include stretch and folds?
Yes. Bulk fermentation begins when the starter enters the dough, and folds normally happen during its early stages.
Should sourdough double during bulk fermentation?
Not always. The ideal rise depends on temperature, flour, dough strength and the planned final proof. Waiting for a full doubling can over-ferment warm dough.
Can I bulk ferment in the fridge?
Cold fermentation is possible, but it behaves differently and is harder for beginners to judge. Most beginner methods use room-temperature bulk followed by a cold final proof.
Why is my dough not rising?
Possible causes include weak starter, cold dough, insufficient time, unsuitable flour or inaccurate measurements.
Can over-fermented dough be saved?
It may be difficult to shape into a tall loaf, but it can often be baked in a tin or used for focaccia rather than discarded.
Today You Learned
- Bulk fermentation starts when starter enters the dough.
- Temperature changes fermentation speed significantly.
- Rise must be judged alongside bubbles, texture and strength.
- Warm dough may need a smaller rise before shaping.
- Under-fermented dough is dense; over-fermented dough loses strength.
- The clock supports observation but cannot replace it.
Build a More Reliable Baking Setup
Our sourdough kits combine an established starter, practical tools and clear guidance for fermentation, shaping and baking.
Continue Learning
Next lesson: Sourdough Baking Timetable
Turn the stages of sourdough into a realistic same-day, overnight or weekend schedule.
A good way to learn
Focus on repeatability before optimisation. Use one straightforward recipe, keep notes on temperature and timings, and change only one thing on the next bake. You will learn faster from three comparable loaves than from three completely different methods.