Effect of LAB on gluten structure breakdown
I've poked around a bit and can't seem to find much, definitive or otherwise, to the above question. I recently made the Hamelman Pain au Levain WW formula. In the past, which really means the small handful of times that I had made it over the previous 4 months, I retarded the dough for not more than maybe 12 hours before pulling it from the refrigerator and then baking the bread. (You may know that is my SOP, shaped dough goes directly from retard to oven, no bench proofing.)
But this time, the dough sat retarded for close to 24 hours. The results were still quite satisfying, but the thought did come to mind, as it had before - Is there a known/desired duration for how long dough can sit retarded prior to the LABs and other acids starting to breakdown the gluten structure in the dough? Does the percent of levain in the total dough effect that timing?
Summary of the components:
- 61% hydration stiff bread flour levain
- 68% hydration TD
- 75% Bread Flour, 20% WW Flour, 5% Rye Flour
For reference, here is the formula I use:
Stiff Levain | Wt. (g) | Wt. (g) +25% | Wt. (g) +50% | AP + VWG? | Bakers % |
Bread Flour | 86 | 107.5 | 130 | 121g + 9g | 93.5 |
Rye Flour | 6 | 7.5 | 9 |
| 6.5 |
Water | 57 | 72 | 85 |
| 61 |
Stiff starter | 19 | 24 | 28 |
| 20 |
Total | 168 | 211 | 252 |
| 181 |
Final Dough | Wt. (g) | Wt. (g) +25% | Wt. (g) +50% | AP + VWG? |
Bread flour | 352 | 438 | 550 | 525g +25g |
Rye flour | 23 | 29 | 36 |
|
WW flour | 117 | 146 | 182 |
|
Water | 355 | 445 | 553 |
|
Salt | 10.9 | 13.65 | 17 |
|
Stiff levain | 145 | 181 | 224 |
|
Total | 1003 | 1252.65 | 1562 |
|
Total Dough | Wt. (g) | Wt. (g) +25% | Wt. (g) +50% | AP + VWG? | Baker's % |
Bread flour | 438 | 548 | 680 | 646g +34g | 75 |
Rye flour | 29 | 36.25 | 45 |
| 5 |
WW flour | 117 | 146.25 | 182 |
| 20 |
Water | 412 | 515 | 618 |
| 68 |
Salt | 10.9 | 13.65 | 17 |
| 1.9 |
Total | 1007 | 1260 | 1542 |
| 170 |
Thanks, alan
Hi alfanso,
Dough degradation depends on many factors. In a sourdough system two thirds of the breakdown is driven by bacterial proteases. To calculate a desired duration would be rather tricky.
Oxygen is the antagonist to proteolysis. So by increasing the redox potential of your dough/levean you can expect your dough to degrade more slowly.
The percentage of inoculum used will indeed be significant. But there are many other factors to consider.. Water activity, salt etc..
Cheers,
Michael
If by redox (another new vocabulary word among many in this thread) you mean oxygenating the dough - I mix "all" my doughs by hand with many French Folds. I try to be attentive to capturing the air/oxygen in each fold (well, I try). If I am successfully doing this correctly then I am contributing to the longevity of the bread.
alan
From what I have seen of your breads, you're doing a great job!
Thanks so much. Getting feedback, of any kind - particularly constructive, is very satisfying. There are so many sharp and dedicated folks on Isle TFL to reference, it's a world almost all its own. In the little over two years of doing the home baking thing, I feel that I've come a long way. My general knowledge is still quite narrow, but as I mentioned in a prior post, I'm in no hurry.
alan
It also would be effected by what specific LAB are present. Each sourdough culture has a unique mix of bacteria and yeast that react slightly differently to specific temperatures. The best option I can see would be to experiment to determine how long you can retard your dough before you see degradation. Maybe mix up a batch of rolls and pull one out and bake it at different times to see if the structure has changed.
Stu
activity in bread http://blogs.scientificamerican.com/guest-blog/enzymes-the-little-molecules-that-bake-bread/
Art the end they discuss protease in bread dough. There isn't much of it going on it seems. Two things to remember even though some bacteria secrete protease on top of the protease in the flour itself two things slow it down to a crawl. Cold makes enzymes work very slowly and protease is an amino acid and protein itself, and is broken down by other proteases.
Since there is little protease activity going on to begin with and being cold for a very long time slows it down more, there isn't much to worry about. I've never had a dough break down due to protease activity. I donlt store dough in the fridge for days on end either.
Here is another article on enzymes in baking http://www.biokemi.org/biozoom/issues/516/articles/2309
Hi Dab,
Your interpretation is misleading. Protease is very significant in breadmaking. Regarding the first link, it's clear to me that they talk about enzymes in the context of yeast leavened dough, where dough degradation is far slower.
Protease action on gluten creates free amino acids (FAA) and it's these which through further enzymatic reactions during baking create the distinctive flavour of sourdough bread. Protease action also softens the crumb. Sourdough systems are far more proteolytic than yeasted, hence the better flavour and softness.
I'm not sure how you can deny the significance of protease. They are what gives extensibility to dough. In excess they make dough lose cohesiveness and eventually turn it into a puddle.
Protease action creates thiol-groups. It's in the Autolisi (Autolyse) article by Giorilli. I know you've read it before!
Tecnica dell'Autolisi (click twice, it redirects on first click)
protease in bread. It is a great little enzyme when it comes to making the gluten less of a rubber band or providing flavor compounds. It is a good thing. I'm just saying that you don't have to worry about making goo with your sourdough because of protease enzyme activity. Like Debra says LAB, in SD don't make protease so we are left with what comes naturally in flour. Cold slows down all enzymes including protease and there is little protease activity in the making of SD bread to begin with. It is one of those enzymes that happens to exist in the right amounts required for bread making. I'm not sure how long you can keep a dough in the fridge and still have it come out right but I have done so to 48 hours and it came out just fine.
That doesn't mean you cant over ferment and over proof the dough which we all have done way too many tines. I have never ever had a dough turn to goo and I do just about everything you can to force it to happen when it comes to making sour bread taking as long as possible to do so. It just isn't an issue.
I'm making Witch Yeast panettone this year for New Year's. That should be fun....
Happy baking Michael
Miscommunication seems to be a theme with us.
Originally I felt you were playing down the action of dough degradation by way of protease enzymes and it still feels that way. The key word from me being significance.
You misread Debra.
"Most sourdough lactobacilli lack the proteinases to break down gluten proteins"
Proteolysis is a two stage process and there are numerous proteases.
Proteolytic enzymes (proteases) are grouped into proteinases and peptidases.
LAB peptidases (a protease enzyme) are what create the free amino acids, completely destroying gluten in the process. You can't develop FAA without losing dough strength.
It's not simply a case of lowering pH. A chemically acidified dough is no match for true sourdough fermentation.
Goo isn't always the end consistency. Where water activity is low, which happens where acidity is high the end consistency is more mush / paste - dough which tears easily. Either way it is all due to proteolysis and gluten solubility. This is over-fermentation.
https://www.researchgate.net/publication/222280579_Proteolysis_in_sourdough_fermentations_mechanisms_and_potential_for_improved_bread_quality_Trends_F...
Good luck with the Witch Yeast Panettone. Happy baking and Merry Christmas Dab.
Regards,
Michael
I don't know if this is related but an observation I have wondered about in the past is when I try to hurry the process by using a larger percentage of starter my bread has a lot less oven spring even though I let it proof to about the same size. The loaves also have a firmer crumb yet spread more in the oven so I prefer to use less starter and more time.
Gerhard
Hi Gerhard,
This is a very noteworthy observation. Most only think of timing when it come to inoculation percentage. But the starter should be thought of as ingredient as it directly impacts the rheology of the dough. More starter tends to equate to more strength, at least initially. A dough that is too strong will have poor oven spring as will a dough that is too weak.
Think of a spectrum where on the one side you have a brick (too strong) and on the other a pancake (too weak). One needs to strike a balance to get the best rise.
Hi Alan,
Your question is a simple one and yet there is no simple answer. As always with sourdough, the answer is, it depends. When talking about proteolytic breakdown of gluten, it depends ultimately on two things: pH of the dough, and how much proteolytic enzyme is present. Cereal grains contribute the enzymes (aspartate-proteinases), and LAB contribute the acidity which turns them on. They are most active in the pH range of 3.0 to 4.5. Acidity in turn, depends on a multitude of factors from how you maintain your starter to the makeup and process of your dough. The amount of enzyme present depends on the flour(s), from crop growing conditions to how refined it is. The enzymes are more concentrated in the outer layers of the grain, so in general, whole grains have the most, and the most refined have the least.
If we're talking about oxidation/reduction of thiol compounds and disruption of disulfide bonding, that's different. But it's also an issue in gluten development. Gluten forms when its proteins aggregate into a mesh-like network. Disulfide bonding between the protein molecules helps this happen by joining them end to end into long strands, and side to side like the rungs of a ladder. It's facilitated by another enzyme present in flour with the help of oxygen, and the physical movement by mixing and kneading. The more disulfide bonds formed, the stronger the gluten mesh. Thiol compounds like the glutathione present in flour, can get in the middle and interfere with disulfide bonds. When glutathione is oxidized, two of them bind to each other at the site that would otherwise be free to react with gluten, thus tying it up. The problem is that heterofermentative LAB -- the kind in sourdough -- like converting glutathione back to the reduced form that interferes with gluten. As a result, heterofermentation tends to weaken dough and make it slacker. But this kind of change can go back and forth. And while strength might suffer, gluten proteins are not destroyed in the process.
Proteolysis breaks up the proteins and is irreversible. Thiol interference only blocks proteins from binding to one another, and is a state that has potential for change to better or worse. Either situation involves many factors in the dance between the microbes and the flour. Both can be happening at the same time, and influencing each other.
You didn't ask about how proteolysis affects flavor [or aroma], but since it was tossed into the discussion I want to show where it fits into the puzzle. Most sourdough lactobacilli lack the proteinases to break down gluten proteins, and so they depend on the enzymes present in the flour (as discussed above). Once gluten is broken into smaller, more manageable pieces -- oligo- and di-peptides -- by the flour enzymes, bacteria can draw them inside for further breakdown by intracellular peptidases. This is how lactobacilli contribute to proteolysis. In short, proteolysis occurs in two stages during fermentation: the primary breakdown of protein into peptides by proteinase activity of the flour; and secondary breakdown of peptides into di-peptides and free amino acids by peptidase activity of LAB.
I'm sorry I can't offer a more definitive answer to your original question, but it's just never that simple with living things :)
dw
that is sort of close to this subject
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC126681/
I think the definitive summary may be a maybe, but there is not necessarily a clear answer.
If nothing else, while a lot of discussion floated somewhere over my head, I hope that professionals like Michael and Gerhard and advance amateurs like dbm can glean information from Debra's extensive response.
So, when I read a formula and see that the levain dough is to be retarded for 12 hours, let's say, then there may well be a lot of wiggle room on either side of the clock, preferably on the later side. I've gone hours past the recommended time frame before but nothing as extraordinary as doubling a long retard, which is what prompted this thread.
I should also anticipate a longer retard with a lower percentage of levain added to the mix.
Well, in keeping with my style of retarding shaped dough, which for the homebaker as I am, allows me to control my schedule, this allows even more freedom to decide when to shape the day prior, and when to bake.
alan
I think that David Snyder looked into some different time for bulk cold retardation when he was developing his San Joaquin sourdough recipe. I have modified his approach slightly in that I combine features of his approach and Hamelman's Vermont Sourdough recipe. My overnight bulk cold retard is done at 38F in a time range of 18-23 hours. I've not noticed any difference in oven spring at all. I find that doing a bulk retardation is much simpler than having several bannetons of shaped dough in the refrigerator. Since I've settled on 500g loaves (yes, I know they are on the small side), I can do final proofing using a linen couche which is fine for my limited counter space.
Heterologous mixtures of microorganisms present very complicated ecosystems. It's difficult to analyze how individual species behave. Even a more simple fermentation process such as wine making where there is a single microbe leads to a variety of outcomes depending on what grapes are used and how the final wine is aged.
The best approach in "scientific" endeavors such as sourdough baking is the old axiom that we used in our laboratory, KISS (keep it simple stupid).
usually w/o regard to the clock for the most part, as long as I hit at least a minimum of 8-10 hours. At this point I am generally unconcerned as to how long the retard goes on for. Into the refrigerator at 10PM, out to bake at 10 AM, or 8 PM - 6 AM, or 10 PM - 3 PM the following day. And, as with you and others, no noticeable change in oven spring.
At least a pair of things in common: my typical batard is also ~500g, although lately I've been pushing them past 600g into the 650g range on occasion. And my middle initial is G, so I too am an Alan G.
If you have any interest, here is my recent blog entry which prompted the initial question. The front half of the entry is with mixed starters and I gave it ~12-14 hour retard. The second, updated part of the entry, was Hamelman's Pain au Levain with a single stiff starter. That was the 22 hour retard. Not much difference to be seen, albeit with two slightly different formulae.
alan (g)