The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Purpose of Bulk Fermentation

Sticky_Fingers's picture

Purpose of Bulk Fermentation

I've been baking naturally fermented breads now for the last 6 months or so and a question came to mind over Bulk Fermentation.   Forgive me if this has already been answered -- please just point me in the right direction in that case.

My understanding behind the purpose of Bulk Fermentation is two-fold:  building up the gluten structure and giving the yeast a chance to leaven the dough a certain amount -- average amounts range from 25-50% or even doubling the volume.  The two timing can sometimes be tricky for both goals to be reached at the same time.  Perhaps in one case, the volume has increased but the window-pane test still fails.  The opposite situation could also occur.  Is there any "rule-of-thumb" as to which goal to prioritize?  Does gluten development outweigh achieving a certain desired increase in volume? -- i.e. is it important to extend the Bulk Fermentation until the gluten is ready, or could that potentially cause the dough to over-proof?  If the gluten structure is fully developed but the volume increase is sluggish, is there any danger in the gluten breaking down if you wait until the dough has finished increasing in volume?



tgrayson's picture

I wouldn't say that bulk fermentation has much to do with gluten development unless it's pretty long. The no-knead bread does most of its gluten development during bulk fermentation, because the dough is highly hydrated and allowed to sit for a long time. Most gluten is formed via mixing and any subsequent stretch & folds, and some during shaping for final proof.

Bulk fermentation is mostly about flavor development and dough aeration.




Sticky_Fingers's picture

tgrayson -- thanks for including the goal of flavor development as well.  I don't use a mechanical mixer, so I depend on a combination of stretch/folds and time to develop the gluten which as you said, occurs during the autolyse,bulk fermentation, etc.  Sourdough takes time, so time is definitely part of the equation in any gluten development for the kind of bread I make. 

I had heard a test that the dough needs to pass in determining that bulk fermentation was complete is the window pane test.  So if you fully develop the gluten early on in the process by mixing -- I assume it would immediately pass this test.  Obviously you still need more bulk fermentation time, for flavor, etc. -- so how do you determine when it's complete?  Do you just know from experience it takes x hours at a given temperature?  And also -- is there any danger of over-fermenting/proofing the dough at this point?

tgrayson's picture

"Sourdough takes time, so time is definitely part of the equation in any gluten development for the kind of bread I make. "

Only in the sense that S&F takes time...if your dough is just sitting there for 3 hours, I doubt that much gluten development is taking place. Personally, I would discount this as a function of bulk fermentation, except for the case of no-knead bread, which depends on a very high hydration and 20 hours of sitting there.

But no matter....the idea that bulk fermentation is over when the dough can pass the windowpane test is a view that I've never heard anyone express. Most people, I think, only use the windowpane test with doughs that are to be fully developed in the mixer. For the long-fermented doughs you're talking about, I know the dough is ready when I can't stretch and fold it anymore because the gluten has gotten too strong. I never use the windowpane test in this situation and I'm not sure it would pass or whether it should pass.

Could this lead to overfermentation? I suppose that if the dough had a high hydration and your folding might not develop enough gluten before the yeast ran out of food. I suspect that most people run into overfermentation mostly during final proof, when you're not continually deflating the dough.

Sticky_Fingers's picture

Thanks again tgrayson for your reply.  It sounds like there shouldn't be a need to be too concerned with overfermentation during the bulk fermentation stage.  With the stretch-and-folds and around 6 hours at 77-78F, I believe my dough on average has enough gluten development and the flavor, for me, is just right.  But, I can see where you might want to experiment with bulk fermenting at different temperatures, and different amounts of time to get a different flavor profile.  If the gluten has been developed properly, either through mixing or other means, then the bulk ferment is over when you find the right combination through trial-and-error as to what produces the flavor result you're after and the dough is ready accordingly.

HorseGuyJohn's picture

Flavour, Flavour, and Flavour.

dabrownman's picture

is about sour dough and that means LAB not yeast.  I have to say that I do whatever I can to restrict the yeast reproduction so that the LAB have more time to create more flavor before the dough is over fermented or over proofed and ready for the heat of the oven.  I also do whatever I can to increase the LAB to yeast ratio in the first place so that there are more LAB to do the sour work from the beginning of the starter, levain and dough..  Bulk fermentation is all about flavor development.  The other thing about getting well rounded flavors in sourdough is to get the LAB to make both acetic and lactic acid - to create the base sour and the 'tang' in the bread and that has more to do with hydration and temperature.

The only time I ever do a window pane test is for breads that need a well defined and developed gluten structure - panettone and other enriched breads made with a mixer.

Happy baking 

Wartface's picture

I use that test on EVERY loaf of sourdough bread I make. It’s the check point to determine when your mixing/kneading step is complete. I will still do some stretch and folds during the bulk fermentation step, after getting a good window pane test though... until my dough doesn’t want to stretch much anymore. 

Bulk fermentation really is the primary fermentation step. The yeast is very active, working hard at rising the dough and the enzymes are busy converting starch and proteins to sugar and alcohol, creating flavor and giving your dough the ability to brown during the baking process. 

I really think using the window pane test is an important step in making sure your gluten structure is developing nicely at the correct time. For me... that’s my permission to move to the next step. 

dmsnyder's picture

The traditional view of bread making divided the process into steps, and "mixing" and "bulk fermentation" were two of them. The role of mixing was gluten development. The role of bulk fermentation was gas production, leading to aerated crumb from CO2 trapped in the gluten-walled cells created during mixing, and flavor development.

These days, especially with "artisan" baking, mixing is more gentle, and the gluten structure is developed through stretch and folds, concurrent with bulk fermentation. Now, gluten develops when (wheat) flour is exposed to water, and it does continue to develop during bulk fermentation, but the gluten strands become both stronger and more organized and able to trap CO2 with mixing or S&F. Essentially, when you fold the dough, you are folding long gluten molecules over each other. When you do this, weak chemical bonds form between the molecules close to each other, and this creates the cellules that hold gas and make the crumb lighter and less dense.

So, gluten is created by flour and water over time.

Gluten is strengthened and given structure by mixing/folding.

Yeast ferments free sugars created by amylase breaking down starch in flour and creates gas that "inflates" the dough.

In Sourdough baking, the LAB's create acids that have many benefits, one of which is to strengthen inter-strand gluten bonds, and another is creation of a host of metabolites that contribute to flavor development. 

The window pane test is in no way a measure of fermentation completion. It is a test of gluten development. I find it of little use in sourdough baking of un-enriched, hand-mixed breads. I do use it with machine-mixed breads more often. Many find it an essential tool. Others don't. Both make good bread.