July 20, 2016 - 10:23pm
Bulk and Proof - what and why?
As I work to get more control over each recipe I try, I wonder what the function of the separate bulk and proof stages are? I'm trying to get better about judging when each is complete, but I don't really understand the distinct functions.
It seems that the leaven is affecting the dough throughout, so why the two steps? I'd like to get better at controlling the crumb of the finished loaf, and also to better judge when each step has served its purpose.
Thanks!
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Bulk fermentation - Yeast and bacteria feed on the flour and water, releasing byproducts that enhance flavor, improve color and cause the dough to rise (gas). Gluten begins to form into linked strands that will help provide support of the resulting loaf. Time and temperature play a big part in how successfully this all works out.
Divide and rest - At a fairly critical time, divide (cut) the fermented dough into specifically weighed portions that will determine the size and weight of your finished loaves.The dough must be handled gently to keep from deflating the gas bubbles and tearing the gluten strands. Let the dough rest for a short time so that the gluten can relax again and gas bubbles can continue to develop.
Shape and proof - Gently degas the divided portions and shape them into the final loaf. Proofing allows the dough to develop internal gas one final time and gives the gluten one more shot at strengthening before hitting the oven.
Bake with steam - Score the loaves to create expansion points and place the loaves in the oven. Introduce humidity, either through moisture supplementation (injection) or moisture capture (cloche). This keeps the surface crust from developing and allows the gas bubbles to expand (oven spring). At some predetermined time either stop the steam injection or remove the lid from the cloche and let the crust develop.
I understand how to do the steps (have done it quite a lot) just not exactly sure why. Is there something different happening chemically in bulk and proof? Are the stages just so that you can manipulate the dough to develop strength and flavor (during bulk) then shape (I don't degas, I like to keep the gas that has accumulated) and then leave it be to rise to its final ready-to-bake state? So I guess what I'm asking is, are the stages just to define between the two processes? Manipulating, building, strengthening (bulk), and a period of rest (proofing)?
I was also wondering if something different is happening in the dough, like in a chemical sense, during those stages? It seems the yeast and bacteria are doing their thing the whole time, independent of the steps we take. But I wondered about the concepts of timing and completion in each step, like two stages of 'readiness'. When bulk is 'done' vs. when proof is 'done'. What's the difference? And (hypothetically) why not have just one stage of 'done-ness' that is just before it goes in the oven?
I hope that makes sense! I know the steps to take, just trying to understand why, and get a better sense of when each is 'done' in terms of what is unique about that step.
Thanks! Jim
Also it seems you're saying to not degas when you divide/rest, but then you do degas when you shape. Just curious about that concept.
At some point you have to interrupt it so that you can shape the dough mass into individual loaves or rolls. And then you let it continue to ferment to the desired degree of airiness. Bulk ferment, as a label, is easy to understand, since it refers to fermenting the entire mass, or bulk, of the dough. The reason for calling the next stage "proofing" isn't as clear; except, perhaps, that it proves to the baker that the dough has reached a ready-to-bake condition.
So, in terms of function:
Bulk ferment - develop gluten network, flavors, bubbles
Knock back / punch down / degas - break up the oversize bubbles, bring yeast cells and food into closer proximity for continued fermentation
Resting / shaping - allows the dough to relax for easier shaping; then form into desired shapes
Proofing / final rise - allows shaped breads to reinflate before baking, further flavor development
Paul
That's making sense. I mean I know this stuff, but there's this judgment about when each stage is at it's peak readiness I think I could understand better than I do!
The reason for doing a final proof is due to the fact that shaping further compresses the dough . Supposing you simply cut up a bulk proofed dough and did not shape loaves and simply relied on funkily shaped loaves you would probably have decent bread only it would look a bit strange and unfinished. As for degassing this is important at final shaping to avoid overly large bubbles especially near the crust !
I think what I'm getting at is why is bulk not ready to bake, aside from of course not having been shaped. In what way is bulk 'ready' (besides shaping) and yet is not ready to bake? What has not happened in the dough, in terms of rise, that happens in that final proofing stage? Or is it just that it's kind of a reset, a slight re-mixing that gives the dough a final boost prior to bake?
Like I said, I'm just trying to sort out in what ways is dough 'ready' or 'done' in the bulk stage (besides shaping) that is not ready for bake? It would help me understand how to judge each stage's 'done-ness' if I was clearer on what each stage was doing for the dough.
Thanks for bearing with a vague question! JH
Sometimes it is. There are recipes where after mixing you give you dough a short rest - 10-15 minutes and then shape and pan it. So you can say that you skip bulk fermentation and go directly to the final proof. Alternatively, there are recipes that skip the final proof, after the bulk fermentation the dough is shaped and immediately baked.
Right, while I'm not looking for reasons to skip either step, I am trying to tease out what each brings to the process to better understand when each has done what it needs to do. Since they are both basically periods that allow the yeast to consume sugars and create gas, etc., they do seem like two steps doing the same thing. But I see that the shaping both creates a nicely formed loaf and also does some slight remixing to give the yeast fresh sources of food.
It comes down to volume. After the bake your loaf should attain the desired volume. Volume comes from two stages - fermentation and oven spring. So say, your loaf is supposed to have a volume of 2 liters, degassed dough volume is 750 ml, and oven spring gives you 500 ml of volume. The remaining volume, 750 ml should come from fermentation, but typically, a fermentation that's long enough to develop gluten, and create flavor and aroma will produce much more gas than that. You then have to split your process in two parts - final proof which will produce 750 ml you need and bulk fermentation, where all the excess gas will be generated and the released during dough work up.
jhaygood, I don't have the answer, but think I understand part of your question. In essence, you are asking, if you bulk ferment for 2 hours, shape, then final proof for one hour, why can't you shape and proof, and allow it to ferment for 3 hours? As I understand it, according to a video by Alton Brown years ago, yeast has very little mobility, and can only eat food that is in close proximity. So bulk ferment is done to allow the yeast to consume the maximum about of food, degassing is actually redistributing the flour and the yeast, so that the yeast cells have access to other food, and then we allow it to continue to ferment to develop volume and flavor. There are some recipes which don't call for a separate bulk ferment and final proof, though the flavor will not be as developed, and there are other recipes that call for degasing more than one, for a finer crumb, IIRC. So as I understand it, we use the bulk ferment to add flavor, and stop that process just before the yeast have run out of food, and then do the degas to redistribute yeast, and do the final proof to increase flavor and volume.
You could always do a test and prove to yourself what the effects are. Small doughs of say 100g flour should do the trick and then compare!
Bulk fermentation times will vary on the amount of yeast used accepting the dough is finished at the optimum temperature of 74 to 82 degrees farenheight.
My 50 year old technical school notes show a table for the amount of compressed yeast required for Bulk fermentation times
8 hours = 1lb per bag flour (150ibs)
7 hours 1.25lbs per bag
6 hours 1.5lbs per bag
5 hours 1.75lbs per bag
4 hours 2lbs per bag
3 hours 3lbs per bag
2 hours 4lbs per bag
1 hour 8lbs per bag
Most doughs in my early days were of the 4 hour BF variety.
Nowadays most plant bakeries have no bulk fermentation period the doughs are mixed at high speed with the addition of chemical additives that condition the gluten strands and will hold gas from the outset.
The main problem with this is that these breads lack flavour. Commercially Bulk fermentation does take up considerable space whilst the doughs GENTLY mature.
When a dough is first mixed the gluten is formed but not fully developed this happens in the slow formation of the gas in the fermentation process which gently conditions the gluten and gently stretches it. The end of the Bulk fermentation process however long that might be depending on the yeast quantity is when the dough is no longer able to hold any more gas.
The dough is then punched down to expel that gas and to even the temperature of the dough and to redistribute any further available food for the yeast cells.
The weighing off is then done and the dough bought into a compact and even shape and allowed to rest and relax for a short time prior to final shaping which should produce even shaped loaves. These are then allowed to prove to close to the optimum gas holding capacity before going to the oven.
Ovenspring should take place if there is still capacity for the gluten to accept the sudden burst of activity from the yeast before it is killed by the heat of the oven.
kind regards Derek
One thing that is still a bit confusing is that a lot of 'artisan' recipes specifically do not degas at the shaping stage. But I guess they are still manipulating the dough enough to give the yeast fresh sources of food. I think I had the impression that not degassing meant that you were not giving the yeast the benefit of that new food but I'm thinking that still happens, just more carefully. Thx!
i think you will find there is a difference in the amount of degassing that is required for different breads for instance sandwhich breads are usually preferred with a tight structure as against cibatta styles that have a very open crumb structure so degassing is relative.