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Bulk fermentation is one of, if not the most important and misunderstood stages in sourdough bread baking. Sourdough bread develops much of its flavor, crumb structure, and rise during bulk fermentation.
Without a proper sourdough bulk fermentation, the sourdough will not be proofed correctly which will lead to an under or over-proofed bread.
This sourdough bulk fermentation guide will cover many of your questions as to why bulk fermentation is important, how to control bulk fermentation, and various indicators to know when bulk fermentation is complete.
Don’t forget to leave your bulk fermentation questions or your own bulk fermentation tips in the comments at the end of the post!
What is Bulk Fermentation?
Bulk fermentation is the first proofing stage between mixing and dividing or shaping dough.
Other words of describing bulk fermentation are first rise, first proof, bulk rise, or bulk proof.
This stage is called bulk fermentation because many bread bakers and bakeries ferment large amounts of bread dough at a time. As a home baker, you might make only one or two loaves at a time, but the same idea applies.
When bulk fermentation is complete, the dough is divided, shaped, and proofed again before baking.
Why is Bulk Fermentation Important?
Bulk fermentation is important because it is the proofing stage when the dough is accumulating gases which will determine the structure and flavor of sourdough bread.
The gluten network you develop from mixing will trap the carbon dioxide produced during bulk fermentation. This will result in the light texture and fluffy interior associated with sourdough bread.
The large, even holes and soft, custardy interior texture of sourdough bread are often called an “open crumb” and are an aspiration of many sourdough bakers. An open crumb can only be achieved with a proper bulk ferment.
Proper fermentation is crucial in sourdough baking and even with the best ingredients, tools, and experience- if you misjudge bulk fermentation, your dough can turn out under or over-proofed.
Signs on how to determine if your dough is properly proofed or under/over-proofed are lower in the post here.
What Do You Do During Bulk Fermentation?
Sourdough bulk fermentation is the longest room temperature stage in sourdough baking and it’s also the most difficult stage to gauge for most people.
Bulk fermentation is largely hands-off as you simply allow the bread dough to ferment on its own schedule. But there are some actions that are taken periodically during bulk fermentation as well which are described below.
I typically proof my dough in a covered mixing bowl, but if you’re making large amounts of bread, it might be helpful to invest in a bulk fermentation container. I recommend this 6-quart storage container for a good bulk fermentation container if you’re proofing many doughs. There are various sizes as well including a larger 8-quart container.
What Are Stretch & Folds or Coil Folds?
Many bakers employ stretch & folds or more gentle coil folds like in My Everyday Sourdough Bread Recipe, Buckwheat Sourdough, or Calabrian Chili and Honey Sourdough Bread recipes during bulk fermentation.
Performing a series of folds during bulk fermentation will help regulate dough temperature, further gluten development, and help you sense how quickly your dough is fermenting.
Either type of fold will be beneficial for your dough. Some bakers have a strong preference for one or the other. I tend to use gentle coil folds during bulk fermentation because I feel like it keeps the integrity of gases more intact which helps achieve a more open crumb.
How Many Stretch & Folds or Coil Folds For Sourdough?
The amount of folds and length of sourdough bulk fermentation time depends on the recipe you’re using and from dough to dough. You’re looking for a balance between how elastic and extensible your dough is.
Too few folds and your dough might be too slack during shaping and may flatten during baking. Too many folds and your dough may have a tight crumb structure.
The more you bake, the more you’ll develop a sense of when bulk fermentation is complete and if your dough needs more or fewer folds.
Since stretch & folds are slightly stronger, a set of 4 to 6 stretch & folds in many sourdough recipes is common. For gentle coil folds, 6 to 8 sets is is typical. Some recipes may use both or another method entirely (like a slap and fold technique).
Check out my YouTube video for how to perform coil folds during bulk fermentation below.
How Do You Control Bulk Fermentation?
The best way to control bulk fermentation is to keep your dough at a constant temperature throughout bulk fermentation.
Sourdough yeasts perform best in a slightly warmer than room temperature environment (75-80ºF or 24-27ºC is ideal).
But controlling dough temperature can be difficult if you live somewhere with fluctuating temperatures and seasons that can have steaming hot days and frigid cold nights like I do.
There are a couple of tools that I use and recommend to control bulk fermentation temperature and I find are extremely helpful in producing more consistent sourdough bread:
- Brød and Taylor Proofer:
- The folding proofer is large enough to hold a sourdough starter container and a medium mixing bowl for proofing at the same time.
- The proofer can be kept at a temperature range of 70-195ºF (21-90ºC). I keep my proofer at a cozy 78ºF which is ideal for sourdough yeasts during bulk fermentation and my sourdough starter.
- Regulating my dough temperature using the proofer, especially during cold, winter months has resulted in much more consistent sourdough bakes for me and overall better sourdough bread.
- Thermoworks Classic Super-Fast® Thermapen®:
- Use the Thermapen to check dough temperature throughout bulk fermentation.
- The instant-read thermometer is by far the most accurate and best-performing cooking/baking thermometer.
- Simply stick the thermometer into your dough and it will tell you the temperature of your bread in a literal second.
- I use my Thermapen for so many kitchen tasks and couldn’t recommend investing in one enough.
Another factor that affects fermentation is the hydration of the dough and if whole wheat flours are used. For example, a dough with a high hydration like my 100% hydration Sourdough Pan de Cristal recipe will proof faster than a lower hydration bread.
Likewise, whole wheat flours have nutrients that sourdough yeasts love. You’ll notice if you use large amounts of whole wheats in a recipe like my Seeded Whole Wheat Sourdough Sandwich Bread, that bulk fermentation accelerates.
How Long Does Bulk Fermentation Last?
Bulk fermentation can typically last anywhere from 3.5 to 7 hours depending on the dough temperature, recipe, and amount of sourdough starter used.
At 78ºF, bulk fermentation usually lasts about 4-4.5 hours for my typical sourdough bread. If colder or if using less sourdough starter in a recipe, bulk fermentation might take longer. A sourdough cold bulk fermentation is not recommended, as the cold temperatures will not proof the dough adequately. Instead, proof the dough in the fridge overnight after it has already been shaped.
The range of time it takes for bulk fermentation to be complete is broad because there are so many factors that affect how quickly your dough ferments.
Factors that impact sourdough bulk fermentation time include but are not limited to:
- The strength of your sourdough starter
- Ambient temperature
- The types of flours or other ingredients used
- Humidity
- And even elevation (higher elevation=less bulk fermentation time).
For example, added sugar can accelerate bulk fermentation, like in my Calabrian Chili and Honey Sourdough Bread. The sourdough yeasts in this recipe consume the honey as sugars at a faster rate than a typical loaf.
While documenting the length of time bulk fermentation takes can be helpful, it is not the most accurate measure of when bulk fermentation is complete.
Instead, sensory indicators are the best signals to know when bulk fermentation is done. Use time as a guide and not as the only indicator.
When is Bulk Fermentation Done?
Knowing when sourdough bulk fermentation is completed can be somewhat of a Goldilocks situation.
With more sourdough baking experience, you will develop a better intuitive sense using sensory clues of when your dough is finished proofing.
Signs That Your Dough is Finished Proofing:
The chart below highlights general signs and indicators to know if your sourdough is proofed correctly or under/over-proofed at the end of bulk fermentation. I also include photos below of various bulk fermentation stages.
Always refer to the indicators used by a recipe as they can vary from these.
Proofed Correctly | Under-proofed | Over-proofed |
---|---|---|
The dough has grown about 50% in size (refer to recipe). | The dough has only grown slightly in size. | The dough might be doubled or more in size (refer to recipe). |
The dough has visible gas bubbles on top of and throughout the dough. | There are no visible gas bubbles. | The dough has many gas bubbles. Some bubbles deflated. |
The dough is jiggly when you shake it. | The dough is stiff and does not jiggle. | The dough will be very jiggly and slack. |
The top of the dough is domed and smooth. | The top of the dough is flat and rugged. | The top of the dough is extremely poofy and might overflow the proofing container. To the extreme, it will be deflated. |
The dough feels aerated and full of air. Generally easy to shape (high-hydration doughs are an exception, as they are difficult to shape). | The dough might be slack due to a lack of gluten development and gas buildup. | The dough feels very wet, slack, or even soupy. Extremely difficult to shape. |
The dough smells yeasty. | The dough might smell like flour. | The dough smells acidic and sour. |
What to do if your dough is under or over-proofed?
Sometimes you decide to end bulk fermentation and when you’re shaping the dough, you notice that something seems off. You might have under or over-proofed your dough!
It’s important to learn how to adjust depending on the bulk fermentation signs above. In most cases, you’ll still end up with a decent loaf of sourdough bread!
If you’ve moved on to pre-shaping or shaping your dough and notice that it is under or over-proofed, there are many different options you can take.
Under-proofed Dough:
An under-proofed dough is much easier to save than an over-proofed dough. This is because an under-proofed dough simply needs to be proofed longer. If your sourdough is not rising during bulk fermentation at all, you might need to strengthen your sourdough starter.
If you notice the dough is under proofed during preshaping or shaping, simply give it a longer bench rest. By letting the dough rest longer during preshaping or shaping, the bulk fermentation stage is essentially extended.
The dough will continue to proof very slowly in the refrigerator, so you can also extend a cold, overnight proof. Depending on the recipe, you might be able to extend the cold proof for up to a few days.
If the dough still seems under proofed once taken out of the refrigerator, let it proof longer at room temperature before baking.
Here’s an under proofed bread I baked and posted on my Instagram:
Over-proofed Dough:
An over-proofed dough is more difficult to save than an under-proofed dough.
If the dough is only slightly over-proofed at the end of bulk fermentation, divide and shape the dough into a banneton immediately and place it directly in the refrigerator. The cold temperature will slow down fermentation and your bread will likely end up okay.
A dough that is extremely over-proofed might not be salvageable for sourdough bread. If it’s so wet and slack that you cannot shape the bread, I would advise making focaccia out of it! Dump the dough out onto a sheet pan with a lot of olive oil, dimple it all over, add salt and any toppings and bake at 450ºF for 20-25 minutes.
An example of a slightly over-proofed sourdough below from my Instagram:
Can You Bulk Ferment in the Refrigerator?
Generally, no. Bulk fermentation is meant to ferment at a warm enough location for the sourdough yeasts to produce carbon dioxide and multiply (ideally between 75-80ºF). In a cold location like the refrigerator, the yeasts ferment at an extremely slow pace, which hinders bulk fermentation.
However, if you’ve proofed your dough for a few hours in a warm location, you can transfer the dough to the refrigerator for the last couple of hours to finish bulk fermentation. Essentially, the yeasts have activated enough at this point that they will continue to expand more in the refrigerator.
Conclusion
Bulk fermentation doesn’t have to be intimidating or as mysterious as it seems.
Most of the process is hands-off; allow the sourdough yeasts to do their job. Another part of it is a baker’s intuition that comes with experience and practice.
Learn the various signs and indicators when bulk fermentation is complete and you’ll be 90% there!
And experiment! Let your dough ferment much longer than normal and see what happens. Or cut bulk fermentation short and see what an under-proofed dough feels like. Those experiments with your dough taken to extremes can help you get to know your dough better and make you a better baker.
Hi, Brandon, Thanks for the detailed information. I usually let bulk fermentation overnight (~70F). The dough raised well (a little over-proofed). I usually wait to second rise then after shaping in baking pan, I baked at 375oC for 30-40 mins. I got very hard, heavy and sour taste bread. Any suggestions? Thank you
Hi Minghua, it sounds like maybe the dough over proofed. At 70ºF, the dough will likely over proof overnight if it sits out. Hence, why most bakers do an overnight proof in the refrigerator, which helps you control fermentation better. The very sour tasting bread is another indicator that the dough was over fermented. I typically bulk ferment for 4-5 hours around 78ºF and then stick in the refrigerator after shaping, then bake the next day!
Hello, So when calculating the time that you spent during bulk fermentation do you start the timer as as soon as you finish all of your stretch and folds/ coil folds or do you calculate that in as well?
Bulk fermentation begins when both the salt and levain (or starter) are added. The folds are made during bulk fermentation.
I was told I should only use glass with sour dough; so I needed to buy a lg glass bowl to mix and rise in. I see the bulk fermentation container from Amazon isn’t glass. ??
You can proof bread in glass, ceramic, metal, or plastic. I recommend the large plastic container here if you’re proofing large amounts of doughs. These are the typical containers that small bakeries use. I personally use Pyrex, glass, or stainless steel containers when I make my own bread at home.
I used a stand mixer to knead my dough. I have the dough in the oven with the light on for the book fermentation. Would I still need to do folds during the bulk fermentation process?
Hi Darci, I still would. It wouldn’t hurt! If the dough feels really strong though after a couple of them, then you could let it rest for the remainder of time.
I wish I could post pictures! I made a smoked paprika, rosemary and sundried tomato yesterday from The Sourdough whisperer book. I did the bulk fermentation from 10am to 5pm. My house temperature was around 67.
I am.not sure what went wrong but I baked the loaf and I ended up with a flat bread…no spring at all 😭😭😭
Suggestions???
Thank you
Hi Carol, I’m not familiar with the book, so I can’t speak to that recipe in particular, but it sounds likely that the dough needed to proof longer. 67ºF is on the cool end of bulk fermentation and the dough can take a long time to double in size at that temperature. Another possibility is if your sourdough starter wasn’t active. Like bulk fermentation, you’ll want to make sure your starter is in a warm location for optimal performance too. I have some sourdough starter tips listed here if you think that could’ve been the issue.
I gave my sourdough several rounds of folding and then let it bulk rise overnight in its baking pan. I then baked it coved at 400 for 20mins and then at 200 for 30mins and it was the fluffiest not so crumbly crust and very yummy! Whenever I shape it after bulk rise it turns out flat so I now skip that part and everyone loves the bread!
Hi Brandon!
Let’s start by saying I have a cold house, running at 68 degrees. I’m almost 6 hours into bulk fermentation and I have the gas bubbles at the top forming mostly on the edges, a couple in the middle. My rise is about 15-20% currently and I ever so slightly see the dome shape. I don’t want to Overproof but when I shake the bowl it’s not very jiggly or airy. I added 90 degree water to my mix so that my dough temp started at 80 degrees. thanks!
Hi Jessica, my house stays cool during the winter too and what I find works best for me and is most consistent is to keep it in a bread proofer or the oven with the light turned on. The dome shape and bubbles sound like you’re on your way, though. If it’s not airy, it probably needs more time. At 68ºF, it might be a couple of more hours.
I say shape it when you’re ready and see how it turns out. If it’s under proofed, you’ll know to ferment it a little longer next time. If it’s over proofed, then cut it shorter next time!
What has really worked well for me with my starter and for proofing is to put a warm glass of water in my microwave with whatever I am working with and close the door. It keeps the temperature really consistent. I also keep a thermometer in there, of course the microwave is not running lol.