December 11, 2009 - 3:23am
Very liquid sourdough
Hi,
I read that most of you use a sourdough with 100% hydratation, just like me.
Recently I came across a more liquid sourdough (130% hydratation) that doesn't actually rise (a lot). It has the consistence of yogurth but it thickens during refreshments. It's supposed to develop exclusively lactic acid (none of acetic acid), and to grow the yeasts better
Did anyone ever use it? Can you share your experiences? Can you explain the differences?
Thanks,
Nico
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Whenever I contemplate answering on a topic as expansive as this one really is, it wears me out just thinking about it, because I think a whole chapter could be written on starter maintenance and how it affects population dynamics and metabolite production. Click here for an introduction to the latter.
I wouldn't change anything that Dan said, but I will add that you will never get all lactic acid, or all acetic acid, no matter what hydration you keep your starter. All else being equal, you will get a lower percentage of the total acid as acetic, at the higher hydrations. Acetic acid will increase as a percentage of the total acid, as the hydration moves downward, but it will never be higher than lactic acid. Lactic acid will always be higher than acetic in a starter or bread dough, no matter what hydration you use.
I recently tried Hamelman's Vermont Sourdough (built on a 125% starter), because it received so many accolades here on TFL. In fact, I tried it twice, because I wasn't sure the first batch was what it should be. I may be the only one, but I didn't care for this bread at all. It was just too sour for me (and I didn't even retard it). But as you can probably guess, I am not a sour seeker. Next I tried the Pain au Levain. It is essentially the same overall formula---same dough hydration, and same percentage of pre-fermented flour. The difference is that it is built on a firm 60% starter, and has 5% rye flour instead of 10. Seemingly small changes, but what a big difference it made in the character of the bread. This one, I loved. It was mild in flavor, and had the most heavenly wheaty aroma.
So, why does my firm starter produce milder bread than my liquid one, when firm starters have a higher percentage of acetic acid? Because it has a lower total acid concentration. More specifically, the bacteria grow slower in a dry starter, so their population shrinks over multiple refreshments (yeast seem to hold their own). Because their population is smaller and they're growing slower, acid production is likewise reduced. But this brings us around to the other factors, which Dan has listed above---temperature, the size of feedings, and the length of feeding intervals. These also play a big part in population dynamics and acidity.
Today, I shall leave it at that : )
-dw
Hi Debra, first I'd like to say that all your responses have been tremendously helpful for me. I would like to ask you a few questions about the Pain au Levain that you mention above:
1. what % of your total flour did you pre-ferment?
2. what was the hydration % of your pre-ferment?
2. the 5% rye flour, was that only in the starter or pre-ferment or in the total flour amount?
3. in the pre-ferment, what was the percent of starter vs new flour?
In general, when baking with 100% whole wheat, what % of the total flour do you try to pre-ferment and at what hydration do you do your pre-ferment? And in your pre-ferment, what percent of starter vs new flour do you use?
Thank you so much,
Andrey
all your responses have been tremendously helpful
Good to hear
1. what % of your total flour did you pre-ferment? 15.5% (93.5% white, 6.5% med rye)
2. what was the hydration % of your pre-ferment? 60%
2. the 5% rye flour, was that only in the starter or pre-ferment or in the total flour amount?
Both. If I remember right, the 6.5% rye in the P-F formula accounts for 1/5 of the rye (1% of the total flour) in overall formula. Make sense?
3. in the pre-ferment, what was the percent of starter vs new flour?
20% for a 12-hour fermentation. The mother starter was 60% hydration, 100% white flour, fed frequently enough to keep leavening high and acidity low. Makes a light, airy bread.
In general, when baking with 100% whole wheat, what % of the total flour do you try to pre-ferment
In general I don't care for sourdough's acidity in whole wheat breads, so I don't make them. I tried desem for a while, and it was milder, but I wasn't loving what, to me, seemed like a strange flavor. The things that promote mildness, aside from keeping the starter at cave temps like desem, is keeping it very stiff, feeding 3 times a day leading up to mixing your dough, use as little prefermented flour as will do the trick (11-18% probably), and try to get it from mixer to oven in about 6 hours or so. There are a lot of enzymes in whole wheat, and they will break down the dough if you take fermentation out too long. But this varies a lot from one brand/type ww flour to the next, so you just have to experiment.
and at what hydration do you do your pre-ferment?
I no longer do naturally leavened whole wheat, but your hydration will depend on the absorbency of the flour --- try both firm and liquid (and different temperatures) to see which gets you the flavor profile you prefer. The last time I used whole wheat sourdough was in Jeff Yankellow's 100% whole wheat croissants. The ww sourdough was 100% hydration -- not firm, but not liquid either. Only about 5% of the overall flour was prefermented (mostly for flavor), and baker's yeast added for lift. I like the compromise.
And in your pre-ferment, what percent of starter vs new flour do you use?
Too many variables to say specifically, but I would do a high percentage of starter (probably 200% or more) for a short time (3-5 hours) if you start early enough in the day.
Thank you so much
You're welcome :)
dw
Thank you so much Debra, I really appreciate such a quick response :) Take Care.
"So, why does my firm starter produce milder bread than my liquid one, when firm starters have a higher percentage of acetic acid? Because it has a lower total acid concentration. "
-Light bulb moment for me. Thanks for that.
I'm really happy to have raised the question because a lot of extremely intersing informations are coming out.
Thanks a lot to both, it's an intriguing matter!
I have another question for you experts:
generally speaking, is the yeast concentration higher in a liquid levain or in a firm one?
In Italy there's almost no colture of liquid sourdough (only firm) and all recipes involving a lot of fats and requiring a very high rise mandate the use of a firm sourdough (it's called mother dough, here).
Professional bakers often repeat that liquid sourdough doesn't have the "strength" to rise panettone and pandoro, that you need a real mother dough refreshed every day at least for a weak to strengthen it enough, but I won't believe them until I find some scientific evidence.
For sure my panettone and pandoro take a lot of time to rise when made with my liquid sourdough, but maybe it's just me.
Nico, you bring up some really good questions, because this is a very complex, confusing and somewhat contradictory area for most people to really grasp. And this has been a difficult post for me to write, because I've attempted to explain this general topic before and only a few people really "got" it. So I hope you'll forgive me for taking some time to get back to you; I've been stewing on it a bit, so as to regroup and take a new stab at it from a different angle.
By "strength," in this context, I think what we're really talking about is the collective power of the yeast to huff, and to puff, and to blow the bread up :-) In other words, a strong rise, or rising power. It is the yeast fraction in the culture that provides the lift. Lactic acid bacteria (LAB) could raise dough in theory, but in practice, they fall flat. So, a good rise is all about healthy, vigorous yeast. Bacteria contribute acids which flavor dough, but also play a big part in gluten structure and rheology. In the short term acid tightens gluten, contributing to dough strength, but in the long term, it accelerates proteolysis, contributing to its breakdown. And it adds sourness that is not welcome in all breads. You'll find yeast/lift at one end of the starter spectrum and bacteria/sourness at the other. You can't maximize both at the same time; one comes at the expense of the other. Where you want your starter to be on the spectrum, depends on the bread you are making. For panettone and pandoro, it sounds like maximizing lift, and minimizing sour is the goal.
I think the key to understanding starters, is to recognize that population dynamics and metabolic effects are two separate, albeit related issues. Population dynamics have to do with organism numbers, and how they interact and fluctuate in relation to each other and to their starter environment. Whereas metabolism is about what those organisms are doing, and what effect that has on the dough. The magnitude of those effects are related to the population numbers. But the numbers are regulated largely by how hospitable the sourdough environment is to the various species, and how much antagonism there is between them. Does that make sense so far?
Dan gave us a good overview of how dough is affected by hydration (some cereal chemistry as well as metabolic effects), but now let's take a look at how the culture is affected---the population dynamics---because that will determine the magnitude of the metabolic effects. Lowering hydration will slow all the microorganisms, yes, but yeasts are not quite as sensitive to it as the lactobacilli. In other words, the growth rate of the bacteria declines more sharply than that of the yeasts. Sourdough LAB thrive in warmth at high hydrations; low hydration and cool temperatures really slow them down. Yeast benefit from this, because they have less competition from the bacteria, so they have more space, and the resources to expand. They aren't quite as hindered by low hydration, low temperature, low pH, salinity, etc., as lactobacilli are, so even if they do slow some, they gain an edge because the bacteria are slowed more. And the one thing that yeast are more sensitive to than lactobacilli---acetic acid---is reduced as the bacterial population shrinks. So, when you knock back the bacteria, yeast tend to flourish, and rising power increases as sourness decreases.
But the key to it all, is multiple refreshments. It's the regular dilution through feeding that shrinks the bacterial population here, because they aren't keeping pace with the yeast, relatively speaking (and starter ripeness, and readiness for feeding is determined by yeast rise and fall). Because it takes some time for the populations to change and re-stabilize, a starter maintained firm (and fed frequently) for at least a week is probably going to give you better results in your panettone than a liquid starter, even one that is firmed up "as needed." It's the difference between a true firm starter, and a firm pre-ferment. The effect will be different, because the populations are different. In a firm culture, you are actually manipulating the starter environment to suppress bacteria (sour) and enhance yeast (lift), whereas a firm pre-ferment is more about manipulating the metabolic effects to increase acetic acid. See the difference? A culture maintained firm will give you less sour (and more lift). A firm pre-ferment made from a liquid starter may give you more. The magnitude of the metabolic effects reflect the relative differences in population numbers.
-dw
Hi,
this explanation is very clear! Finally I found what I was searching. The only thing that leaves me some doubt is the "ripeness" of the firm SD: can you elaborate a bit more? I'm still confused on this behalf. I don't know if I'm feeding my starter at the right time because I don't know how to correctly evaluate whether it's the right time or not.
Thanks very much to you and Dan for your precious help!
I'm so glad it was helpful. Dan's photo is a very good guide. The middle shows what my firm starter looks like at feeding time, though I sometimes feed sooner to reduce the sour quicker. If you go much past what the picture shows, especially on a regular basis, the bacteria catch up, and even the firm starter turns sour. Timing is everything : )
I have recently asked you this very question in a message but just now found the answer here. Thanks Debbie!
You're very welcome :)
I have come back to this post again (each time I pick up something different :)) and wonder how the levain build is influenced by method. i.e is it better to refresh your firm starter (discard and feed) several times thus diluting/shrinking the bacterial population before you build your actual levain for your bread or is it better to do multiple steps or builds i.e one seed amount of starter with additional feeds over 12 - 24 hour period? which would give the milder SD?
I maintain a 66% hydration starter in the fridge. Would 60% hydration give a milder SD and would this then be dependent on refresh/ build method?
Leslie
Well, it all matters. But for different reasons at different times. Just remember that how you maintain your mother is what directs the evolution of not just relative sizes of the various populations within, but also the species and strains which come to dominate the community. Genetically, the microorganisms all differ in what they can and can't do for your bread's flavor and texture, so together, these are what create potential for what your breads can become. The quickest thing you can change is LAB:yeast ratio (sour:lift), particularly with refreshment rate/frequency, degree of ripeness, hydration, temperature, and to some extent, flour. It's not just one thing, it's everything. The species and strains (the character of your starter) can change if your changes in maintenance are prolonged or permanent. That is not as immediate as LAB:yeast ratio, which is very dynamic. It's that dynamic nature that you can take advantage of in your levain build.
What you do in terms of refreshing your starter should be about what is best for your starter to preserve its desired character and potential, and to keep it invigorated. What you do in building and manipulating your levain should be about aligning it for the bread you want to make (but starting from a healthy, vigorous mother, not a sluggish one from longtime storage). As I said above, you can change the sour:lift balance fairly quickly. But if you do too many consecutive intermediate levain builds that are very different from your mother's maintenance routine, you run the risk of unexpected consequences of natural selection. If what you're asking me is more about the total quantity at each feed than about changing up the proportions, then yes, you can start with a tiny amount and build it with successively larger feeds. You don't have to discard, or maintain a large quantity, but you do need to feed adequately to keep things mild.
As to which will give you the milder bread, I can't really answer that because it depends on the sum total of all the inputs, and the condition of your mother starter. The devil's in the details, and I'm not clear on what we're comparing :) But no matter what, at the end of the day, you have to do the experiment to find out what will happen. ...And then come back again. Learning this stuff is more like climbing a long spiral staircase than a straight ladder. But each time you come back around you'll be a level higher :)
My best,
dw
there is much to think on, and my bread is always improving. manipulating the starter is just one of the steps on that spiral staircase. :)
Leslie
Hi Dan,
your explanation is very clear and very convincing, but as usual it raises another question.
As you said the "madre" is supposed not to be sour at all, becuse the general practice is to tie it tight after a refreshment and make it ferment until it almost bursts (in a sense it actually bursts, literally!), then refresh it 3 times at 4 hour intervals. (what's the correct term for this practice? "tying" doesn't sound good to me.)
I don't know the inner working of the processes involved, I even opened a thread today asking for clarifications. What I'd like to know if this tying causes an increase of the yeasts count or a strengthening of the dough overall, or if it's just a way to reduce fermentation and acidification as someone else told me.
The point I want to get to is this one: I simulated the same procedure on my liquid levain: I filled to the rim a small jar with my sourdough just fed, closed it tight and made it ferment at ~28C for 4 hours. As I expected it opened the top quite violently and overflew ;). Will this procedure strengthen my liquid sourdough? Or do I risk some negative side-effect such as souring?
Thanks,
Nico
No longer relevant
One bite at a time : )
I've been putting off this part of the discussion, not only to get past the holidays, but because I really don't know how best to approach it. I've alluded to it, hinted at it, and danced around it, but the elephant isn't getting any smaller. In the past year, I've introduced Fresh Loafers to a range of interrelated topics on the more technical side of sourdough microbiology, including bioenergetics and metabolite production (here, and here), population dynamics (here, and earlier in this thread). Now it's time to add microbial growth kinetics into the conversation. But, let's take it one bite at a time. Right now, I just want to lay a foundation, and then we can build up from there as time permits.
So, what the heck are microbial growth kinetics? I do have a tendency to pull out the technical terms, don't I? That's okay, I think Loafers can handle it ;-) Most simply stated, what I'm talking about is the pattern of change in population size, over time. In a sourdough culture, it begins at the time of refreshment. If you plot cell numbers on a graph, using a logarithmic or 'log' scale for the vertical axis, and time along the horizontal, a characteristic pattern forms.
Lag Phase: The population size remains about the same during this time. The cells are acquainting themselves with, and adjusting to, the new environmental conditions brought about by refreshment, and they're busy preparing themselves for growth. The length of the lag phase depends in large part on temperature, the inoculum size, and the condition of the cells.
Growth Phase: Also referred to as the exponential phase or log phase, this is where the population is doubling at regular time intervals.
Stationary Phase: The stationary phase is brought on by a dwindling food supply and/or the build up of toxic waste products. Energy production becomes less and less efficient as energy needs increase. As in the lag phase, there isn't much change in population size. The cells start initiating physiological and morphological changes to shut down or reduce energy-consuming cellular processes, so that they can conserve themselves and extend this phase as long as possible.
Death Phase: The cell number starts declining. When the energy demands of survival exceed a cell's energy-producing capacity, it will die.
A word about this and coming diagrams: I don't apply any actual laboratory values to these, because nothing is constant, and everything is variable (which will be more apparent later on). Since you won't be taking cell counts at home, the numbers have little practical value anyway, and tend to be so huge as to be mind-boggling. You can see and taste the effects, which is what really matters. So, my graphs may be exaggerated from what they are in sourdough, because they are general, and meant only to be conceptual, as a visual aid to understanding the dynamic relationships.
Okay, that's a big enough bite for one day : )
-dw
P.S. It may be a few weeks before the next installment, and I apologize for my lack of talent in the art of illustration.
... for your excellent explanations in this thread. Thank you for taking the time to do all the write-ups. Here at The Fresh Loaf, we are so lucky to have you and Dan to explain to us the mechanics inside the sticky, wobbly mess called starter. We are so privileged. THANK YOU.
Shiao-Ping
I was about 4 or 5 posts up and thought, "Boy, I need a graph." Imagine my excitement when I saw it was in log scale!!!! Really, it helps.
Now, if you could draw 12 of them comparing the activity of yeast-vs-acid for dry-wet and hot-cold and lay them out in an array for hot-cold and dry-wet, I could see it all. No, I'm not asking.
Thank you very much (Debra & Dan) for sharing your knowledge and your patience in doing so. Off to bioenergetics & metabolite production..
Rick
For the last fortnight I have searched for and read / reread Debra Wink's posts on the Fresh Loaf website. There is a lot to learn and unlearn about sourdough. I am grateful to you both for maintaining the site and helping me with the art and science of sourdough.
Thank you for your kind words. Glad you're finding some value in things I've posted; and you're right, there is much to unlearn. But just so you know, Floyd Mann is the owner and maintainer of this site. I'm just a member like you :)
All good wishes,
dw
Plenty enough for today! Thanks, Debra
Sylvia
In my last post, I showed what a general, microbial population growth curve looks like, to introduce some terms and patterns you may or may not be familiar with---lag, growth, stationary and death phases. You may have noticed the similarity between the way the population size increases and decreases, and the actual rise and fall of a freshly fed starter. First, there is stillness for a period of time before you start to see bubbles forming. Then, the bubbles start coming faster and push the starter upward until it peaks, or reaches the highest point that it can. The level may even stay at that point for some time before starting to recede, eventually ending up back at the starting level. So, it's very easy to conclude that one is an indicator of the other, but it's not quite that simple.
While CO2 is one of those metabolic effects I talked about earlier, for which the magnitude is related to population numbers at any given time, it is also related to the condition of the individual cells and the rate at which they are pumping it out. Whenever yeast cells are respiring or fermenting sugars to generate energy, they are producing CO2. So the rate of gas production is a good visual indicator of the overall metabolic activity in the yeast population. But if you've read my post on factors affecting microbial growth, you know that metabolic rate doesn't necessarily correspond to reproductive rate. The yeast may be working hard just to maintain homeostasis, as is the case when waste by-products build to toxic levels, or the temperature rises higher than their comfort zone.
The rise and fall of a starter doesn't pinpoint exactly when yeast stop reproducing, but it does give us a good indication of when the population is most metabolically active---and that is very important. However, a well-kept sourdough starter will never see the death phase, because it will be refreshed well before the population size starts to decline. That's not to say that the starter won't collapse and shrink in volume---that's just metabolic activity and gas production slowing to a hault. Yeast enter the stationary phase when they can no longer produce enough excess energy to reproduce themselves, either because there is no longer enough food to turn into energy, or because the accumulation of waste by-products forces them to use all their energy on survival. But rather than continuing to fight a losing battle, they go into sort of a shut-down mode to turn off energy-consuming cellular processes and conserve themselves for better times.
They start making physiological and biochemical changes that allow them to reduce their energy needs, so that they can suspend their metabolism and remain viable even though sluggish or inactive. The starter may shrink as metabolism slows and production of CO2 comes to a halt, but the population may remain high for some time, declining only slightly for quite a while. For that reason, I am extending the stationary phase indefinitely and adding an overlay of what gas production might look like in relation to population size.
Note that while rise and fall in a starter will correspond to rate of CO2 production, the overall expansion is limited by physical properties of flour and hydration. A thick starter with strong gluten can trap and hold onto the gasses more effectively, rising higher, longer. In a thinner starter, bubbles rise to the top and release their gasses into the atmosphere much faster, producing less or no rise, but not because gas production is any less. Only because the gas is percolating through and out of the starter, rather than being held in. The reason it is generally advised to refresh after the starter has peaked and is only beginning to show signs of receding (although there are some exceptions to this), is because that is the point at which you know the yeast population has reached its maximum for that growth cycle, and you want to feed again before the yeast start to shut down. Keeping them active helps build vigor and leavening power.
-dw
Hi Debra,
thi is *very* interesting.
Many recipes for rye breads that I'm preparing recently state to let the poolish collapse completely before preparing the final dough, in order to decrease the PH of the dough. I was just wondering if and how much the yeasts would die during the collapse, as actually the final dough rises as fast as when I used the poolish at the top.
Your posts explains very well the effects I'm seeing.
Now, is there any way to determine how much of the yeasts population is dormant and how much of it is dead after the collapse?
Thanks for you explanations and for all the time you dedicate us!
Hi Nico,
Yep, this is one of those cases where you refreshed at a different point (far right) along the curve to achieve a higher level of acidity, and when I get to adding the lactobacilli into the picture, I think it will all be even clearer. When using the wrapping/tying method we talked about earlier for non-sour firm starters, the refresh point would be somewhat left of where I have marked. So there is some room for adjustment, depending on the desired effect.
I can't give you concrete numbers or times because it depends on various factors, but I doubt there is any significant decline until well beyond the collapse point. And if the starter is healthy and vigorous going into this final build, the population won't even have really shut down yet---first they go into more of a stand-by mode, from which they can resume activity relatively quickly, and that seems to be what your results reflect. There are degrees to the process.
-dw
Mrs. Wink (I was taught never to call my teachers bu thier first name)
Finally finally things are starting to come together love the story building going on.. but of course the suspense is killing me .. love the graphs.. love it all!
One question (for now) you say that with a wet starter (due to it lack of gluten development) will start to fall before the "stationary phase" - but how is the falling a definitve sign of maximum yeast population as I seem to understand you.
You can't imagine the joy your clarity brings me... I dont know how I can thank you.
please keep your posts coming.. I feel like a kid reading a comic book.. geting to the last page every week and reading the words "to be continued".
Thank you so much.
-Charlie
Mrs. Wink was my mother-in-law ;-)
That's not quite what I'm saying there. It's not that a really wet starter will fall sooner, it's that it won't rise as high. Falling shows that the CO2 production is slowing down, which wouldn't happen while the population is dividing at regular intervals, because that requires high metabolic activity. So, it isn't going to fall before the stationary phase (unless the temperature drops). Make sense?
-dw
Fantastic thread. My thanks to all who are do the asking and answering.
Jeff
Last time, I believe we left off in the stationary phase, which is a good starting point for today's topic. Stationary phase begins when a population can no longer generate enough excess energy to increase in number, and ends (for our purposes) at the time of refreshment. It is brought on by changing conditions in the starter environment---namely, depletion of resources and/or build-up of inhibiting substances. When cells find it increasingly difficult to produce enough energy even to maintain homeostasis, they begin physiological and biochemical changes to slow or turn off energy-consuming processes and conserve themselves for more favorable times. It's not something that happens all at once in sourdough, but a process that proceeds increasingly over time. Think of the stationary phase as a resting phase, where "rest" starts out just dozing off, but progresses over time, into a deep hibernating sleep.
If stationary phase is resting, then lag phase is waking, which must happen before a sleeping population can start growing again. It takes longer to wake up from a deep sleep than from a short nap. And so it is with resting cells. All of the physiological and biochemical changes made to suspend metabolism in the stationary phase, need to be reversed in the lag phase for cells to return to activity, and that takes some time as well. So, how sluggish and dormant the cells become, has an impact on how quickly they can return to their active state. The longer a population remains in stationary phase, the longer the next lag phase will be. That is one reason why you may find that a starter fed once a day or less, doesn't snap to quite as quickly as one fed twice a day or more. Or a starter forgotten in the back of the refrigerator for months can take well over 24 hours to show the first signs of life. But chances are, things are not as dead as they may appear, the organisms need more startup time.
The horizontal axis represents time, the vertical is population size, and the dashed lines represent refreshment points. This diagram is meant to show what happens when stationary phase is prolonged. Note that the next lag phase is much longer. Feeding at the end of growth phase/beginning of stationary phase several times in succession, will help to reduce lag time, and increase vigor.
Physiological condition of a cell population is just one factor influencing lag phase. Another is change in the starter environment---in pH, temperature, salinity, gas composition, energy sources and nutrients, inhibiting substances, etc. In general, the bigger the change, the longer the lag time because there are more internal adjustments a cell must make in response. For example, when water availability is reduced by decreasing hydration or adding salt, a cell must either manufacture or pull in from its surroundings a proportionate amount of compatible solutes to counteract the tendency for water to be drawn out. A big enough change in temperature may require cells to readjust the fatty acid and protein makeup of their membranes in order to maintain enough solidity to preserve their ordered structure, while at the same time, enough fluidity for nutrients and other substances to pass through. Proteins, saturated and unsaturated fatty acids need to be balanced, and because they change between solid and liquid at differing temperatures, the right balance changes with the temperature. As nutrient supplies change, various metabolic pathways are turned on or off by mechanisms that sense the presence or absence of substances in the cell's environment.
So, a lot goes on inside a cell in preparation for growth---more than I can do justice to. But hopefully this gives a general idea. Point being, that cells must adjust to the degree of change which comes with refreshment. And the thing that most determines the degree of change in the starter environment, is the refreshment rate. By that, I mean the ratio of fresh flour and water to mature starter. The greater the refreshment, the greater the change and the longer the lag time. Also, independent of its potential to change, temperature is an important factor in its own right. All else being equal, lag phase is shorter in warm temperatures and longer in cool.
Well, I don't know about you all, but to me, that feels like about a big enough bite for one day. So, I'll give you some time to digest that before taking on the growth phase---because there might be a little math involved :-o
Don't worry, it won't be painful :-)
-dw
are always very clear. I'm sure your math won't be scary ;)
welcome back to this new installment, Debra! It's always a pleasure watching thourgh the magnifying glass you offer to us readers.
As for temperature I noticed that my starters (solid and liquid, refreshed every 24 hours) tend to get pretty warm as fermentation proceeds. I keep them in covered glass jars that in turn stay in a plastic box. I bet that from refreshment time to top rise they gain at least 3-4°C because they are warm to the touch, especially the solid one. My house is always around 23°C. Is this temperature increase excessive or does it fit in a normal state of affairs?
Nico
Hi Nico,
Just doing a little adjusting to realign the image. After referring someone to this thread (an oldie, but a goodie), I noticed the right side was cut off. Things shifted here and there in the site upgrade, and I guess I missed this one.
Microorganisms do generate some heat. How much of it is retained depends on a number of variables, but a 3-4 degree rise isn't outrageous ;-)
Are you ready for panettone season?
dw
Panettones every weeek end, and yes, they are coming out nicely now that I've learned what my little friends like and how to treat the dough.
After all the troubles I had I stabilized on a technique: single dough risen for 4 hours at room temperature, than 2-3-4 days in the fridge and finally the last rise in the mold. Panettones rise hugely and come out soft and aromatic. Dough prepared with this procedure seem to be stabilized during the long cold retardation, even though Janet is scared:)
Using the liquid or the solid starter doesn't make a difference. Maybe the liquid one performs better, but marginally.
I'm relieved to know that my starters don't have fever:))
I'm not at all surprised you have found a way to make it work on your terms. Just goes to show that understanding what, when, where to apply temperature, and why, is what makes it an effective tool.
You get it : )
P.S. You must send me some photos of your panettones during the holidays.
Here are some pictures
http://laconfraternitadellapizza.forumfree.it/?t=67346988 (almost 100% butter)
http://laconfraternitadellapizza.forumfree.it/?t=67466272 (exactly 100% butter)
https://lh4.googleusercontent.com/-k5IHkkkCrS0/UkVhw6OMlVI/AAAAAAAAB6I/BFSLQTDigFw/w640-h480-no/2013-09-27+11.55.00.jpg
As you can see they are all very rich doughs. Recently I stabilized on a "salomonic" recipe: same weight of flour, whole eggs and butter + 50% sugar + 30%starter and 2% salt. The method that changed my experiences from night to day is txfarmer's intensive mixing, but on steroids:). Using the paddle I knead at very high speed until the dough comes together perfectly. Using whole eggs helped me a lot.
Previously, when I needed gently, egg whites helped my dough come together, but the baked crumb dried out very soon. Using the intensive mixing method the crumb remains perfectly moist as it's desirable, no more dryouts. I guessed that all the energy I use may lead to denaturing of the ovotransferrins that are blamed to squeeze water away when they oagulate during baking. Do you believe it's a plausible explanation?
As you can see I was forced to use much less dough for the mold (800 gr of dough is the ideal amount for a 1 kg mold). Tjis method works so well that in the second case I was able to use 100% durum wheat flour for the dough, a flour that is far from being strong.
Nico
Hi Debra,
Thank you so much for picking this up and writing more about what is happening in our starters. I also really appreciate the diagrams you included. I find that diagrams stay in my mind so much better than words so retrieving and understanding the information becomes much easier for my brain
It is hard to find such easy to read and understand information on the macrobiotic end of baking so I always appreciate anything you contribute here!
Janet
You're welcome, Janet, and thank you : )
Over the summer/autumn here I have kept my starter on the bench and have been feeding it twice daily and at increased ratio to starter. Your post is a timely reminder as our days begin to cool to review my procedure. It suits me to feed twice daily so I've been planning to lessen the ratio to starter in order to keep the same interval between feeds. I assume by making such changes I'll be altering the population ratios of the various microflora at peak, but I guess that contributes to the never-ending variety that helps maintain my interest in baking sourdough.
At the beginning of the summer I had both a liquid (100%) starter and a firm (60%) starter but found the 100% rather demanding to keep in hot conditions (ie shorter & shorter lag times) and so decided to only keep the firm one and make hydration adjustments during the levain build. However I have kept thinking about what the difference in microflora population must be between well maintained liquid and firm starters and whether I am kidding myself by altering the hydration over a feed or two. Maybe with the cooler weather I'll get two going again and do some experiments to find out what difference there is in flavour and proofing times using a 100% maintained starter and a firm starter converted to 100% hydration over the day before baking.
I'll be interested to hear your comments on the growth phase.
Regards, Robyn
Please post your results when you find out! I'd be so interested in what you decide after you've done some baking with both a firm and liquid starter that are maintained as such. I've been keeping my starter relatively firm in the fridge and simply converting to what I need in a single build when I bring it out, based on what the recipe calls for. But, in reading Debra's and other poster's stuff, I'm beginning to think I may be falling short of what I could really be experiencing in my breads. Perhaps after the summer here in AZ I'll give it a try myself, maintaining two starters on the counter, rather than in the fridge.
This week I'm going to try doing some multiple builds before baking and see if I note a difference in vigor and taste, both in my rye bread and whole wheat. Not very scientific as we are getting very warm in the RV. Won't be able to do much until I'm back in the house and temperatures fluctuate less.
Just got my grain mill and can't wait to see how my starters respond to fresh grain. I feel like feeding them just to see how they act!!!
Last installment, I think I stopped at the influence of temperature on lag time. Temperature also provides a good starting point for the next phase: Growth. Just as temperature plays a big part in the length of the lag phase, it greatly influences growth rate as well---not so much in the final number of organisms, which is limited more by other things, but in the generation time (how long it takes a population to double). The closer the temperature is to optimal for a species, the faster its population will increase. This goes for the other factors as well---pH, water activity, food sources, inhibiting substances, etc.---the closer everything is to optimal, the faster the organisms will reproduce.
Whereas the stationary and lag phases represent times of little to no net change in population size, the growth phase is where cells are metabolizing sugars at a relatively high rate, and the population is doubling at regular intervals. But the threshold between lag phase and growth is not a sharp one, as in going from 0 to full speed at a specific point. There are no sharp angles on a population growth curve. There is a ramping up, especially during that first generation as the cells get going in the transition from lag to exponential growth. So, the first doubling is generally the slowest, and then the generation time decreases as long as conditions remain favorable and there are enough resources to continue growing. Similarly, at the top there will be a slowing in the last generation as the population transitions from growth back into stationary phase. So, generation time in the growth phase is influenced to some extent, by the number of generations in between the low and the high. The population increases fastest, somewhere in the middle. How can you tell how many generations that is? Your refreshment rate will give you a pretty good idea.
If you maintain your culture in a consistent manner, it settles into its own equilibrium. The organisms tend to reach about the same count in about the same time, in about the same ratio to each other when feeding follows about the same rate and frequency each time, with the same flour and hydration, at the same temperature. Changing any of those factors can shift the equilibrium, but the microorganisms will shift and adjust until they find a new equilibrium, which will once again remain steady so long as the maintenance routine remains steady. Whew! That almost sounds like a legal disclaimer, doesn't it? Since the populations are reaching essentially the same highs and lows before and after feeding (in a stable culture, maintained stably), we can draw the connection between refreshment rate, which is a dilution factor, and the number of generations your culture grows between refreshments. You can figure this out quickly from a ratio, a baker's formula, or actual weights, simply by adding up the starter, flour and water, and dividing the total by the starter amount.
Note that even though 16x is a very large dilution, it represents only one more generation time than 8x. And that generation time will be added in the middle of the steepest part of the growth curve where reproduction is happening the fastest. So, even though the lag time will be a bit longer when making big refreshments, don't expect the ripening time overall to increase by the same factor as the refreshment rate. For this reason, I find it much more useful to think about starter feeding in terms of dilution factors and generations, than in baker's percents or weights.
Well, I think that about finishes the ground level :-) Next time we'll build up from there, integrating the LAB to see how they relate to yeast and to starter maintenance.
-dw
Hi Debra,
very nice reading once again.
I have a question about the generations count: does your schema apply when the hydratation is much more than 1, say 2.5? For example, if I used a refreshment rate at 250% hydratation would I get something like 1:5:2 = 8x accounting for three generations? I mean, wouldn't such a big dilution in so much water with so little flour affect the count of micro-organisms?
Thanks as usual,
Nico
Hi Nico,
Yes, it works at any hydration (so long as the starter is stable in that feeding regime), because your starter is at the same hydration as the refreshment. It's all about proportion. If/when you're changing hydrations, then the above doesn't really apply until the starter has readjusted and become stable again. There will be a transition period whenever you change something (hydration, temperature, refreshment rate, frequency, etc.). That's why I stressed a stable culture, maintained stably. We're only talking about routine (and consistent) starter maintenance here, not making preferments or dough, where the proportions are different, or salt is added.
And, yes. Hydration will have an effect on the microorganism count (I'll get to that later), but we aren't looking at absolute counts just yet. Only relative values, and how they relate to population growth patterns. This is about the factor of change and number of generations between the low and the high, not the actual low and high values. Hopefully, it will all come together in the end. There really is a method to my madness ;-)
-dw
"Next time we'll build up from there, integrating the LAB to see how they relate to yeast and starter maintenance."
Debra,
I recently came across a graph that credited you as the author and did overlay the LAB over the yeast. But I would much rather read something that you authored first-hand. Did the LAB discussion as the next step ever take place? (You've said many times that they are slower than the yeast, but I haven't found a graph like the one I found on www.brodandtaylor.com.)
Sorry if it's around here and I missed it. I thought I gave a pretty thorough search...
True story, yesterday I walked to the book store to pick up P.R. whole grains. While there I found, The Rye baker, I purchased the book, unknowing I actually met the author; here at the fresh loaf, some years back. Stanley Ginsberg was very gracious, and fun to chat with.
Before yesterday, I had no idea what "lactic acid producing bacteria (LAB) was. In his book, Stanley, talks about how ingredients, that create an environment, that favor LAB production are used in rye breads. The goal being, to stave off the effects of amylase degradation AKA, "starch attack". Maybe Mr. Ginsberg will see this post and add some insight on the subject of LAB in starters.
I own that book and have read the sections you mentioned. I'll take a second look. Thanks.
BB,
I haven't written the next level and beyond, mostly because I started teaching it (as lecture) in classes at King Arthur and elsewhere. But also because the site was becoming more commercial, it no longer felt like the right place to publish.
You've said many times that they are slower than the yeast, ...
Well, that doesn't sound very much like me. :) LAB grow faster than yeast, they just start later. It's a very important distinction. Otherwise, they wouldn't stay in balance.
All best,
dw
is that the reason I wanted to find.something directly from you is to avoid what I just did...inaccurately repeat what you said. Apologies. I did understand that distinction but I didn't state it clearly. They start slower. :-). Thanks for correcting the the record.
Hi Debbie,
Continued, and many thanks for posting all this incredibly complex information about natural yeast and LAB. I am, for one, very appreciative; though I'm sure I speak for many.
We [Nico was involved in this as well] have been discussing a problem apparently arising from excessive and rapid proteolysis in dough. We were unable to reach a definitive conclusion on the effect of temperature on enzymatic reactions. Nico was under the impression that refrigeration would not slow down enzymatic reaction. The small amount of trawling through academic work which I have done suggests that the cold climate does indeed slow down rate of reaction. Are you able to impart any of your scientific wisdom to this debate please?
For the full post, if you haven't seen it, you can fid it here: http://www.thefreshloaf.com/node/18144/sourdough-loosing-elasticity-please-help
Thanks again
Andy
Hi Andy,
Maybe SteveB would care to comment about the effect of temperature on enzymatic reactions. He is our resident chemist :-) But, after reading through the thread, I don't believe that proteolytic enzymes are the poster's problem. I should take care of business here in this thread first, then I'll work my way over there.
Until then ...
Hi Debra
Thanks for the latest installment. I continue to regret that they are hidden on a thread, which longer term will make it harder to retrieve from archives. Would you consider collating them in a post on your TFL blog sometime.....
I'm afraid I haven't been able to infer what you mean in practical terms when you state:
When you feed your starter, with these thoughts in mind, what are you seeking to achieve? What do you actually do to achieve this?
Hammelman teaches us to focus on starter peaking. I established my starter in spring (using the PJ method you have brought to our attention), over the summer and autumn we had reasonably consistent temperatures so I had the 'stable culture maintained stably' to which you refer. Now winter has begun, with the change of temperature, the time til peak has increased. While I have now moved it from the counter to the hot water cupboard, the timing to peak isn't as practical as I had been experiencing. I'd been able to feed (1:3:5) a 60% starter twice a day (12 hourly). I have been considering experimenting with decreasing the feeding ratio in the hope of getting back to the more easily managed 12 hour interval (I did also have a 100% starter but gave it up over summer as it was peaking in less than 12 hours and as I did get the firm starter stable, I didn't spend the time working out a maintenace programme for the liquid one - the reverse of my current predicament). The temperatures will continue to get colder, my home is not centrally heated, and even the environs of the hot water cupboard will get colder, esp overnight.(I have also thought that perhaps I should consider trying a larger feeding ratio and changing to once a day feeding)...
My question is, if I were instead to think 'in terms of dilution factors and generations' as I seek a practical maintenance schedule over winter (which may need to be altered more than once), what would I then proceed to do in practical terms? (And presumably reverse at year-end as temperature head back up again)
With kind regards, Robyn
PS I am concious I am asking a question about firm starter on a 'very liquid sourdough' thread!
Since the questions were asked in this thread, and it's where the discussion unfolded, I would prefer to keep it here, all together, rather than to break the continuity. That is... as long as that's okay with Nico.
But it's easy enough to keep track of threads here at TFL just by adding them to your favorites, or subscribing to the ones that interest you so that you'll get an email notification whenever there's new activity. Either way, you can have easy access to them at any time through your account. If it's the thread title that bothers you, maybe you can talk Nico into changing it at some point to better reflect the overall subject matter.
I probably will pull this all together and polish it up at some point, but I need to finish it first. You guys are my guinea pigs ;-) Let's just hope I'm successful.
I just meant that it's not so obvious when looking at a refreshment formula in baker's percentages or weights, how much your culture is actually increasing, and what impact the feeding rate has on the populations. The number of generations is a useful piece of information in understanding population dynamics.
Ahhh, good question. But that's a topic for a future installment :-)
As do I. Looking at the dilution rate or number of generations doesn't change that.
Go ahead and play with your feeding ratio, and if you don't like the results, then we can probably find something to adjust :-)
-dw
Hi Debra
I do however rush to say, it's not for me that I expressed concerned about the location of your very useful material, on the contrary, I'm fortunate enough to know where it is; it's for others in the future who may not find their way to this thread. With so much material on TFL it takes skill to use the search box effectively. I am glad to hear that you will consider bringing it all together. Perhaps it may be as simple as leaving a link to this thread on your blog. I have really appreciated your contributions in this thread and I'm sure others in the future will too, if they can locate it.
I did know what your response regarding my starter would be :-). But did hope a different angle to think from, might help me overcome my hesitancy to make changes to my feeding programme. I've decided I'll keep some going as it is, until I come up with a stable system using a different feeding ratio which suits me in terms of both timing and final product. Whilst I would like a routine that is more manageable time-wise, the various breads made with the current regime's starter have been great. Guess there's only one way to find out what will happen to my bread when I start making changes!
Again, thank you for your generosity,
Robyn
Thanks, Debra and Dan! This thread is amazing, I've never had more satisfactory explanations of sourdough (other than from Debra and Dan in the past, when I managed to destroy a whole wheat bread by retarding it).
1) I bake almost every day but occasionally skip a day. If I feed my sourdough starter at the end of a baking day, will it be ready in morning or will it have gone past the optimal time to use it?
2) If I bake on Monday and feed the starter at the end of the day but don't bake until Wednesday, should I have fed it again on Tuesday?
Debra, I'm coming to this several years removed from the last comment, but your posts have been extremely helpful in allowing me to be much more comfortable with the whole process.
Thank you!
Read for further sourdough development: www.thefreshloaf.com/node/51434/pure-lactobacillus-sanfranciscensis-culture-or-powder-anyone-please
that after almost 10 years this thread is still a subject of very inspiring discussions and reflections (even though I haven't touched flour for more than a year now, so sad).
Dear Debra Wink, Nico, and all the others on this post,
THANK YOU so so much for such clearly detailed and interesting info regarding the biology and growth cycles of the yeasts and bacteria in the starters. After reading through this and some of Debra’s other posts, I felt inspired to start a rather large experiment to make and maintain 5 different starters from scratch... a control which was just WW flour and spring water. The three other jars have a different addition each... probiotics, honey, and thyme. The final jar is only Rye flour and water. I’ve been trying to keep all other variables (temperature, location, refreshments) equal, so I can see how the different additions in the starters affect the micro-environments of yeasts and bacteria growth. I’ve been tracking the rise (or lack thereof) every few hours over the course of 7 feedings now (I started last Thursday and it’s currently 3:30am Tuesday).
I would LOVE any insights from Debra or Nico or anyone who has experience with making and maintaining starters. In particular, I am fascinated that the thyme starter has consistently been the fastest and most consistent one to rise between each feeding, especially because it’s essential oil has strong antimicrobial properties. I wanted to try to cultivate the bacteria that have (through natural selection) developed an association with the thyme... but now seeing how well they are growing, I’m honestly a bit worried about exactly what bacteria I’m growing.
I posted all the details of my experiment so far under the Sourdough Starters thread of the forum yesterday. Please, can anyone provide any insights??
Thanks so much!
Mary Dake
If so I guess that the fast activity that you have seen is due to microflora present on the surface of all vegetables. I imagine that the thyme oil is present in tiny amounts in the innards, and probably it hasn't had a chance to be released to the sourdough (generally oil extractions requires crushing and the use of a solvent like alcohol or hexane).
I've just started a Greek sourdough starter with Basil leaves. Don't know if you saw this post.
I wonder what the Basil leaves bring to the starter...
Also just bought this flour for when the starter is ready. Organic 50:50 mix of bread and durum flour. Perfect for the recipe following. High quality.