Author Topic: Cold fermenting in refridgerator with sourdough  (Read 4825 times)

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Online TXCraig1

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Re: Cold fermenting in refridgerator with sourdough
« Reply #20 on: February 04, 2013, 10:24:47 PM »
Thank you for your additional thoughts. I think you're right that they do not go completely dormant. I'd like to find out just how much they do go dormant though.

I will continue my experimenting, mostly because I just enjoy the process. I am making a 12.75% starter dough tonight and plan to repeat experiment number 4 above. This is an assumption that a certain % of yeast have irreversible damage after being subjected to low temperatures for an extended amount of time.

JD

I can't think of any basis for such an assumption.

In your #4, you wrote: "Although the dough seemed to be fully fermented, spring & color were very poor. I'm now beginning to suspect that the fridge actually damages the yeast in some way."

If the dough looked fully fermented but didn't spring, wouldn't that seem to suggest that there had been an adverse effect on the mechanical structure of the dough itself rather than on the yeast? It sounds like the yeast did their job but the dough failed.

This is what I've been trying to tell you. It's not about damage to the yeast. Extended SD cold fermentation is not good for the dough itself.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #21 on: February 04, 2013, 11:09:24 PM »
I can't think of any basis for such an assumption.

In your #4, you wrote: "Although the dough seemed to be fully fermented, spring & color were very poor. I'm now beginning to suspect that the fridge actually damages the yeast in some way."

If the dough looked fully fermented but didn't spring, wouldn't that seem to suggest that there had been an adverse effect on the mechanical structure of the dough itself rather than on the yeast? It sounds like the yeast did their job but the dough failed.

This is what I've been trying to tell you. It's not about damage to the yeast. Extended SD cold fermentation is not good for the dough itself.


The reason I suspect yeast damage is because my 14 day ferment had great spring & color. So if that dough wasn't damaged why should the 5 day dough be damaged? I used the exact same process.

Also I should point out that the appearance of fermentation of the 5 day dough was lots of little bubbles, but it did not gain much volume.

My only explanation of the 14 day success would be that a certain percentage of yeast died out initially, and the strong survived. After 14 days the strong yeast cold fermented enough to multiply back to the amount near the original starter %, and a 24 hour warm ferment kicked off the real fermentation process.

I know it sounds crazy, but what other variable might I be missing? The only thing I've been changing is the cold temp ferment time.
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #22 on: February 05, 2013, 09:05:57 AM »
Was the dough for experiments 1-4 all made in one batch? If not, was it all made at the same time?
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #23 on: February 05, 2013, 09:07:39 AM »
Was the dough for experiments 1-4 all made in one batch? If not, was it all made at the same time?

It was not. Same process, same materials, different day of the week.

Your point is noted.
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #24 on: February 05, 2013, 09:35:58 AM »
It was not. Same process, same materials, different day of the week.

Your point is noted.

I would say that renders the results of the experiments invalid as there is no way you could control the starter activity level nor the enzyme or acid level of the starter with suitable precision. I think it is critical that any results you want to compare come from the same batch of dough. Likewise, subsequent sets of experiments should include at least one control that has been previously tested, and if the control doesn't get the same result as in previous experiments, you must reject all of the results of the other tests in that set.

Also, if it is weak yeast dying off and stronger yeast replicating that explain the difference, shouldn't that cause you to reject your hypothesis that the yeast go virtually dormant? By "weak" do you mean genetically less fit, or simply old and tired?
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Re: Cold fermenting in refridgerator with sourdough
« Reply #25 on: February 05, 2013, 10:03:56 AM »

Something else to consider: there are some key factors that determine how much energy yeast and bacteria can generate: temperature, hydration, salinity, pH, food supply and metabolic pathway (aerobic or anaerobic). In the case of a young dough, generally speaking, food supply is always high and oxygen is always low, so the others are the ones we need to be concerned with.

There are three main functions for which yeast and bacteria use energy, homeostasis (the basic cellular processes to maintain a stable environment inside the cell – i.e. life), growth, and division. There is a hierarchy as to how energy is spent; first is homeostasis, and only if there is energy left over, is there growth, and only if there is still energy left over, is there division. As the external environment becomes less ideal (temp too high or low, pH too high or low, salinity too high, food too low, etc.) , the less efficient the cell becomes and the more energy must be devoted to homeostasis – simply staying alive – leaving less for growth and reproduction.

Extended periods of cold hit the yeast two ways – lower temp and lower pH. Both require the cell to devote more and more energy to homeostasis. 100% of the energy the cell has available comes from carbohydrate metabolism, and as previously discussed, this creates CO2. If you see signs of CO2 being produced, you have energy production. This does not mean you have significant division however, and if you’re not seeing much in the way of bubbles in the fridge, it’s not very likely that you have any meaningful division.

I bring this up because even if you’re right about weaker cells dying off, you probably don’t have reason to believe they are being replaced by stronger cells.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #26 on: February 05, 2013, 12:50:07 PM »
Something else to consider: there are some key factors that determine how much energy yeast and bacteria can generate: temperature, hydration, salinity, pH, food supply and metabolic pathway (aerobic or anaerobic). In the case of a young dough, generally speaking, food supply is always high and oxygen is always low, so the others are the ones we need to be concerned with.

There are three main functions for which yeast and bacteria use energy, homeostasis (the basic cellular processes to maintain a stable environment inside the cell – i.e. life), growth, and division. There is a hierarchy as to how energy is spent; first is homeostasis, and only if there is energy left over, is there growth, and only if there is still energy left over, is there division. As the external environment becomes less ideal (temp too high or low, pH too high or low, salinity too high, food too low, etc.) , the less efficient the cell becomes and the more energy must be devoted to homeostasis – simply staying alive – leaving less for growth and reproduction.

Extended periods of cold hit the yeast two ways – lower temp and lower pH. Both require the cell to devote more and more energy to homeostasis. 100% of the energy the cell has available comes from carbohydrate metabolism, and as previously discussed, this creates CO2. If you see signs of CO2 being produced, you have energy production. This does not mean you have significant division however, and if you’re not seeing much in the way of bubbles in the fridge, it’s not very likely that you have any meaningful division.

I bring this up because even if you’re right about weaker cells dying off, you probably don’t have reason to believe they are being replaced by stronger cells.



This is very nice information, thank you for sharing.

I understand your explanation completely, and I agree about your conclusion. I just want to share my train of thought so you understand how my brain processes this new info.


Assume 100 people are left out in a winter desert overnight with nothing but a t-shirt and shorts. Just like your yeast survival hierarchy, there is certainly a hierarchy of survival for a human being. An important note would be that every human will react to an outside environment differently. Therefore (for example) of the 100 people, 22 will die, 48 will have hypothermia and lose limbs, and the remaining 30 will survive with no major injuries.

Do yeast have the same variations in survival? I don't know. If they do it would be to a much lesser extent than humans since they are "simple" organisms.

One more thought would be that the yeast on the outside of the dougball would be subjected to lower temperatures than the inside the center of the doughball. Perhaps my "weaker" yeast are simply the yeast within 1" of the outer layer of the doughball.

I understand this is an unusual experiment with no added benefit for "big picture" pizza making. It's just something I started that I'd like to continue. I'm going to use your suggestion on my next experiment and make 1 large batch of pizza dough, divide and scale into 3 separate doughballs, then make them at 3 different times over 2-3 weeks.

I already made the 12.75% last night so I'll finish that experiment first.

Thanks again for your input.


Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #27 on: February 05, 2013, 01:27:54 PM »
Assume 100 people are left out in a winter desert overnight with nothing but a t-shirt and shorts. Just like your yeast survival hierarchy, there is certainly a hierarchy of survival for a human being. An important note would be that every human will react to an outside environment differently. Therefore (for example) of the 100 people, 22 will die, 48 will have hypothermia and lose limbs, and the remaining 30 will survive with no major injuries.

Do yeast have the same variations in survival? I don't know. If they do it would be to a much lesser extent than humans since they are "simple" organisms.

This is where i was going when I asked "by 'weak' do you mean genetically less fit, or simply old and tired?

There are always going to be older cells that will die more quickly when stress increases, but you are talking about the other case - natural selection - survival of the fittest. Your are suggesting that there are cells with a greater ability to maintain homeostasis in colder conditions and the offspring of these cells will share that ability. You are also suggesting that the difference between the two types of cells (those that can and those that can't) is so stark that you will see a difference in only one dough-making cycle. I tend to doubt this is the case, however uf you are right, and if you were to grow a new SD culture out of the old dough and repeat the cycle a couple times, you should have a strain of SD that is super cold resistant.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #28 on: February 05, 2013, 01:44:21 PM »
This is where i was going when I asked "by 'weak' do you mean genetically less fit, or simply old and tired?

There are always going to be older cells that will die more quickly when stress increases, but you are talking about the other case - natural selection - survival of the fittest. Your are suggesting that there are cells with a greater ability to maintain homeostasis in colder conditions and the offspring of these cells will share that ability. You are also suggesting that the difference between the two types of cells (those that can and those that can't) is so stark that you will see a difference in only one dough-making cycle. I tend to doubt this is the case, however uf you are right, and if you were to grow a new SD culture out of the old dough and repeat the cycle a couple times, you should have a strain of SD that is super cold resistant.



That's an interesting twist to my assumptions. An evolution of yeast, so to speak. This wasn't the intent of my experimentations but sounds like an interesting side-experiment. You would assume a starter that is "put to sleep" in the refrigerator (such as mine) would start to take on these attributes though. It's also the assumption that the offspring of cells actually maintain the parent cell attributes as you mentioned. I'm no microbiology expert, so I cannot comment on this claim.

Anyhow, a successful experiment of a single dough-making cycle is certainly not a reason to contact Popular Science magazine, however if the entire "cycle" is repeated many times and shows similar results, I'd start questioning the validity of my assumptions.

Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #29 on: February 05, 2013, 02:29:01 PM »
You would assume a starter that is "put to sleep" in the refrigerator (such as mine) would start to take on these attributes though. It's also the assumption that the offspring of cells actually maintain the parent cell attributes as you mentioned. I'm no microbiology expert, so I cannot comment on this claim.

I would not make that assumption. What would be the basis? Excluding the presence of a mutagen, it is a good assumption that the offspring of cell division are genetically identical to the parent. These cultures, such as Ischia, have been around for a long time. Weaker strains should have died off long ago. This is why they generally don't change over time the way cultures you capture locally tend to change as they mature.  Why would you assume that all the yeast in your culture are not substantually similar having decended from the strongest yeast? Maybe they are not, but I don't see a basis for that assumption off the bat. 

If you're going to be scientific, your null hypothesis would be that there is not enough difference in the cells for the yeast to naturally select into a meaningfully more cold-resistant culture. It's not enough to get a result that suggests your alternate hypothesis (that the yeast culture will become more cold tolerant after exposure to colder temps) is correct. You must disprove the null hypothesis which is much more difficult.

My doubt lies in the idea that the difference is so stark between the less and more cold-tolerant cells that you will see a difference - let alone in one cycle.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #30 on: February 05, 2013, 02:45:21 PM »
I would not make that assumption. What would be the basis? Excluding the presence of a mutagen, it is a good assumption that the offspring of cell division are genetically identical to the parent. These cultures, such as Ischia, have been around for a long time. Weaker strains should have died off long ago. This is why they generally don't change over time the way cultures you capture locally tend to change as they mature.  Why would you assume that all the yeast in your culture are not substantually similar having decended from the strongest yeast? Maybe they are not, but I don't see a basis for that assumption off the bat. 

If you're going to be scientific, your null hypothesis would be that there is not enough difference in the cells for the yeast to naturally select into a meaningfully more cold-resistant culture. It's not enough to get a result that suggests your alternate hypothesis (that the yeast culture will become more cold tolerant after exposure to colder temps) is correct. You must disprove the null hypothesis which is much more difficult.

My doubt lies in the idea that the difference is so stark between the less and more cold-tolerant cells that you will see a difference - let alone in one cycle.

Without completely de-railing this discussion, I would agree with you that all yeast cells would be 99.9% identical. But that 0.1% remaining would be the basis of evolution as we know it. While the yeast are probably 99% similar now as it was 500 years ago, I might argue that due to the process of evolution they have actually changed since then. This evolution is probably undetectable by us, but wouldn't mean it didn't happen.

Back to the topic on hand: This discussion does compliment your argument that the difference between cells would not be enough to see a difference in the big picture. To that I give you a point.


How about the argument of external yeast vs. internal yeast?  Seems a much easier pill to swallow.
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #31 on: February 05, 2013, 03:31:33 PM »
Without completely de-railing this discussion, I would agree with you that all yeast cells would be 99.9% identical. But that 0.1% remaining would be the basis of evolution as we know it. While the yeast are probably 99% similar now as it was 500 years ago, I might argue that due to the process of evolution they have actually changed since then. This evolution is probably undetectable by us, but wouldn't mean it didn't happen.

Back to the topic on hand: This discussion does compliment your argument that the difference between cells would not be enough to see a difference in the big picture. To that I give you a point.


How about the argument of external yeast vs. internal yeast?  Seems a much easier pill to swallow.

It would probably be a case of adaptation not evolution. And maybe you're right about 0.1%, notwithstanding it seems highly unlikely that 14 days in the fridge could develop that that level of difference to something you can quantify with casual observation vs. 5 days in the fridge or 1 day in the fridge.

I'm not sure what you mean by external yeast vs. internal yeast?
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #32 on: February 05, 2013, 03:37:16 PM »
notwithstanding it seems highly unlikely that 14 days in the fridge could develop that that level of difference to something you can quantify with casual observation vs. 5 days in the fridge or 1 day in the fridge.

Yes I understand now what you've been trying to tell me, and I agree.



One more thought would be that the yeast on the outside of the dougball would be subjected to lower temperatures than the inside the center of the doughball. Perhaps my "weaker" yeast are simply the yeast within 1" of the outer layer of the doughball.


I'd like to call this the igloo effect ...
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #33 on: February 05, 2013, 03:47:02 PM »
I'd like to call this the igloo effect ...

You might stick an instant read thermometer in one and see how long it takes the ball to equalize at the refrigerator temperature. I can't imaging it takes very long - certainly not compared to 5 or 14 days.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #34 on: February 05, 2013, 03:55:32 PM »
You might stick an instant read thermometer in one and see how long it takes the ball to equalize at the refrigerator temperature. I can't imaging it takes very long - certainly not compared to 5 or 14 days.

The idea was that (similar to mass effect) the center of the doughball would be slightly warmer than the exterior due to activity of the yeast, and therefore never equalize.


Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #35 on: February 05, 2013, 04:38:29 PM »
The idea was that (similar to mass effect) the center of the doughball would be slightly warmer than the exterior due to activity of the yeast, and therefore never equalize.

I say no chance the difference is meaningful. You've already told me that there is almost zero activity in the fridge. I doubt if it is >0.1F. Maybe if you have 40kg of dough in bulk at room temp, but not one ball in the fridge. I stand to be corrected if measurements prove me wrong.
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Offline JD

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Re: Cold fermenting in refridgerator with sourdough
« Reply #36 on: February 05, 2013, 08:05:35 PM »
Well it looks like I solved the mystery of why the results from experiment #4 were out of place.

I took a digital probe thermometer to the dough to test the difference in temperature between the exterior & center of the dough. My dough temp was a blistering 31*F. I put this dough (as well as experiment #4 dough) in the lowest drawer of my fridge.

I took a temp of food sitting on the middle shelf where my previous experiments were and got 36*F. Top shelf foods were 40*F. Amazing the temperature difference. I imagine the yeast in Dough #4 was in fact "damaged" from below freezing temps.

Still going to continue my original experiment and stay on the original middle shelf (36*) from now on.


Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #37 on: February 19, 2013, 09:35:34 PM »
I had some excellent results tonight. Probably going to stick with this recipe and see how it holds up over a few additional days fermentation.

17" NY Style using Ischia
Cut from my personal excel sheet:


   Total Weight   752.1   Grams
59.0%   Water   255.0   Grams
100.0%   Flour   432.2   Grams
3.0%           Salt   13.0   Grams
10.0%   Starter   43.2   Grams
2.0%           Olive Oil   8.6   Grams
   1   Ball(s) Desired   
   741   Gram Ball Size (with loss)   


24 hours in fridge, re-balled than 24 hours at 65*. I made the dough using GM Better for bread flour. I did an identical dough tonight but used ADY & All-trumps bromated. The results were only slightly different, where flavor was in favor of the Ischia dough, and color/dough strength in favor of the all trumps dough. Never had much luck with top crust color, but flavor completely over-shadows that flaw. Camera also isn't the best quality so crust looks more pale than it actually was.


Edit: Added picture of reheated slice in better light
« Last Edit: February 20, 2013, 12:56:34 PM by JD »
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #38 on: February 19, 2013, 09:46:06 PM »
Here's the results of the same formula but with All-trumps bromated + ADY
Josh

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Re: Cold fermenting in refridgerator with sourdough
« Reply #39 on: March 06, 2013, 12:28:09 PM »
I had some excellent results tonight. Probably going to stick with this recipe and see how it holds up over a few additional days fermentation.

17" NY Style using Ischia
Cut from my personal excel sheet:


   Total Weight   752.1   Grams
59.0%   Water   255.0   Grams
100.0%   Flour   432.2   Grams
3.0%           Salt   13.0   Grams
10.0%   Starter   43.2   Grams
2.0%           Olive Oil   8.6   Grams
   1   Ball(s) Desired   
   741   Gram Ball Size (with loss)   


24 hours in fridge, re-balled than 24 hours at 65*. I made the dough using GM Better for bread flour. I did an identical dough tonight but used ADY & All-trumps bromated. The results were only slightly different, where flavor was in favor of the Ischia dough, and color/dough strength in favor of the all trumps dough. Never had much luck with top crust color, but flavor completely over-shadows that flaw. Camera also isn't the best quality so crust looks more pale than it actually was.


Edit: Added picture of reheated slice in better light

I believe that due to the re-balling, especially in the lack of presence of sugar, you will most likely always have a lack of top color. However, there are a couple of other factors you may want to consider..
1. Position of your stone in the oven (assuming you're using a home oven), a higher position would help with the top browning especially in an electric oven with a top element. You may also want to include some broiler time during the bake, that will also help.
2. For the amount of starter and basically a 48 hour ferment, I dont think there is going to be enough residual sugars left within the dough to provide the color you desire. Especially with the re-balling and lack of added sugar to your dough.

There are always a miriad of factors at play with any dough.. I hope if you consider employing these into your regimine that they work out for you. All things considered, practice (and experimentation) make perfect. You're well on your way.

You may want to have a look at member Glutenboy, I believe he employs a long ferment as well as a re-ball and has had good results. Seems along the lines of what you're doing.

Good luck,
Anthony
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