Individual Starters and their Unique Characteristics
I wonder. Have we taken into consideration that starters are unique and produce individual results? I have read (and believe) that our starters have basic similarities. The type(s) of yeast and LAB(s) that are found in one starter will often be found in another. From what I’ve read, it seems that the microbes in our starters (the world over) have more in common than not.
What I hope to discuss in this post is the characteristics of our starters. Some starters double in 2 hours while others may take 12. Some starters will maintain maximum rise for hours where others may not. I’d venture a guess and say that some starters favor different temperatures than others. Many bakers liken their starters to pets. And have even given them names. We all know how different one pet is from another. None behave exactly the same.
Considering the above, I wonder - are we aware of the possible variables that a sourduogh culture introduces to our bread baking? For most of the sourdough bakers with experience, I think we are. But probably our awareness is unconscious. I know mine is.
If we were to forego our starters and use commercial yeast, our baking variables would greatly (maybe completely) be eliminated. If we knew our flour and water, and could control the temperatures, we would be able to follow a recipe instruction with precision.
But sourdough is both art and science. The instructions, especially timing, for SD bread are given as a generalized reference. And we all do well to take them as just that. If the baker fails to mention the temperatures at ferment, we’re even more so on our own. My point is, even though the baker has instructions that are precisely detailed, temperature and all; how can the instructor know the characteristics of each of our starters? His or her starter may double in 3 hours, when it takes 8 hours for mine to get there.
Natural fermentation is an art. I believe many of us are drawn to sourdough because of that. And then there’s the flavor...
Dan
If asked this before, but still looking for clarity.
Is it possible that one starter will produce more open crumb than another? Consider 2 scenarios. The starters are equally active. The second senario, there are not equally actvive. I don’t see how, but I’d like to hear from others.
Dan
producing different crumbs but I recently noticed that young levain (max 8 hours fermentation at 24c), slightly shorter bulk proof (divide when the dough feels billowy and cohesive) and 10 to 12 restin a 4c fridge has produced a really open crumb with great ears. So for me the key has been to capture the time the levain is young and has just enough time to bubble up.
Interesting, Robert. You mentioned using a young levain. Your levain is young when fermented a max of 8 hr at 24C. But my levain may be completely fermented in that time and those conditions. Also the ratio of seed to flour and hydration makes a tremendous difference concerning timing.
With that said, how would you describe your young starter? Some thoughts that come to mind are the percentage of rise relative to maximum rise. Maybe the appearance of the surface, especially if the levain is a wet one. Maybe the dome if the starter has a lower hydration. Possibly the smell. I have even tasted the starter.
Your “young levain” suggestion is a great one. But you can see from above that the time and temp is decriptive, but a description that entails time and temp as a guideline and also one or more of the five senses could be more accurate.
What is it about your young starter that indicates that stage?
Dan
btw - I think one of my biggest problems at this time is over-fermentation. Your reply is on the money...
I feed my mother once a week 100% had white flour. When I want to make bread my levain is 60g white, 40g rye and 100 water. The starter is not very liquid due to the rye but it’s ready when probs doubles in size, sweet tasting and properly floating in the water. I used to think that if I fermented the levain until the gluten broke down somewhat I would see the magic open crumb but it’s actually the other way around in my experience. The 8hour time is more of a guide for me because I go for the smell, taste and appearance.
because I am finding the exact same thing. My crumb and oven spring we’re getting much better with the shorter bulk and a 9 to 12 hour refrigerated proof, but this past weekend, I used a 5 hour Levain and I got the best open crumb ever!
By the way, my Levain is a combo of 3 sources, 2 from people here and one homegrown. It lives in the fridge in a thick state (I quit weighing a long time ago, just add till it is nice and thick), and gets fed when it gets low. It gets fed left over bran, or whole grain flour or AP if that’s all that I have handy. I usually take a few grams and do 3 or so builds to make my levains (I do weigh amounts when building the levains for baking).
Danni, how would you describe the stage of your levain at 5 hours. I am getting interested to try a young levain.
Danny
Lots of bubbles and still sweet smelling. It hadn’t quite doubled but I don’t think it was going to rise any higher.
My first build was 1:1:1, then I doubled the water and flour for the second build and again doubled the water and flour of the second feeding for the third build.
I let it go 12 hours for the first 2 builds and only 5 for the last one.
Remember that my levains include a lot of bran so even though they are 100% hydration, they are thick without a lot of gluten development. I try to get all the bran in the first or second feeding depending on when I get around to milling the grains for my bread.
I think my process is pretty close to what Dab does. After all, he coaxed, prodded, and coached me to go this route for a more open crumb. ?
vs low extraction, flour type, etc. is the crux of this discussion. But I think there may be some things that misguide:
1. The discontinuation of levain expansion is not necessarily indicative of the culture ceasing activity. A starter could double or quintuple then fall over a varying amount of hours and the fall is not a sign of the metabolism of the microbes slowing down or stopping, it's first, and more likely, a sign of the gluten of the starter lacking integrity to hold CO2 produced by the microbes. The microbes will keep producing C02 after the levain falls.
2. Stirring a starter doesn't redistribute food for the microbes. It reorganizes the gluten matrix allowing the continued trapping of C02--which never stopped even after the starter fell.
And so perhaps training our noses to detect the desired range is more reliable than visual cues from expansion. Sniff for a young fresh levain; a more predominantly alcoholic but mild and sweet levain; an overly ripe and pungent levain; etc.
But perhaps I have this wrong.
Tom, there may be exceptions, but for the most part, it is my understanding that a receding starter is an indicator that the yeast are being overtaken by the LAB. This is not to say that there are no yeast, but the LAB are increasing in proportion to the yeast. A starter will either favor yeast or LAB, but they definitely always possess both.
It is commonly accepted that stirring a starter will redistribute the food supply. It will also produce increased gluten strength. And unless the starter is completely exhausted it is expected to rise again.
Yesterday and today, I experimented with Doc’s method to evaluate a starter. Unfortunately, I am not knowledgeable at this time to give a concise writeup. But basically the starter is weighed at a specific interval, in my case every hour. Because the yeast are actively consuming sugars from the starch and expelling CO2 there will be a slight loss in the starter weight. Over time this loss is calculated to determine the readiness of the starter and also the degree of the strength (yeast) of the starter. If interested I can try to get more info.
Dan
This thread with Mariana responding to your questions seems to suggest the opposite:
1. Yeast benefit from Labs; generally as there is lab growth, yeast will grow at approx 100:1.
2. Stirring a starter reorganizes the gluten matrix to trap the co2 that did not cease even though the levain reduced in size. The stirring does not re-feed the microbes.
Would be good to have her join this thread, try to clear things up.
Also, the concept of yeast producing the co2 to rise the dough may be antiquated. Apparently Labs produce almost half of the co2.
Yea, I read that this morning.
Mariana is a bread genius! I’d like to have her input on this or anything else she comments on.
Yeast and LAB are said to have a symbiotic relation. One benefits the other. But when it comes to stirring the starter, it makes sense to me that stirring a starter will bring the microbes in contact with new food.
If I am incorrect about this or anything else, I am happy and willing to learn my error(s). “The truth sets us free”.
You can click Mariana’s icon and pull up her PM. I’m sure she’ll help us in any way she can.
Danny
very interesting and very topical for me today.
Leslie
atm. Yesterday left it for 12 hours at 82-85° F, stirred it down and left as temperature dropped. photographed when I could. Today I have taken that starter made another firm starter (mine is about 65% hydration) and made a 100% hydration one and I am leaving today at room temp, which was about 22°c when I started and now 4 hours later is about 24-25°0c. Will post my photos in a thread once I have completed. showing some interesting things. good for me to learn how my starter behaves.
Hi leslieruf
I'm interested in how you'd predict changes in starter activity at different temps. In your post you switch from F to C... 82-85˚F is 28-29˚C, which is much hotter than the later temps you describe. Does your starter last 12 hours at those temps? How do you adjust your planning when room temp is 29˚C as opposed to say 26? I'm curious, as our temps in Mauritius are regularly in the late 20s and early 30s (˚C) and I'm having to try wing it with a newish starter and some newbie sourdough learning...
Best
Lisa
We use Celcius here in NZ but such a lot of info is in Farenheit. My thermometer gives both. 80° c was a suggested temperature so I aimed for that. I work with both but usually don’t convert, lol. My oven is celcius, I read internal temps of my bread as farenheit, room temperature is celcius etc.
There are some formula that say BF at 80°F and so I use my microwave as it is spring here. In summer I will work around whatever ambient temperature I have, and just watch the dough because proofing times will be much shorter and things will happen faster. In winter I can usually manage 21° c as the heating will keep daytime temperatures at that. I don’t have a temperature controlled proofer either.
I guess, working with cold water is another option for you, even cool your flour in rhe refrigerator to slow things.
Leslie
I keep my starter in the fridge, but if you just go by my experiment your starter would last 12 hours perhaps longer, but would need feeding either every 12 hours or at least daily. thats quite a tie in my opinion but there are lots of folk that do that. mine gets fed monthly more or less and I have very little discard.
Ah, New Zealand, ok that makes sense for those temperature ranges. Yes, I think refrigerated starter is the only way to go in the kind of temps I contend with. I've killed way too many starters in my time!
The ratio of LAB to yeast tends toward ~100:1 (not the other way around)
In a starter, gluten development is irrelevant.
You don't need to stir a starter to redistribute the sugars or the yeast or the LAB. Diffusion and Brownian motion seem to do a quite adequate job. To demonstrate this: mix up a batch of flour and water (5g each) and add a few drops of bromthymol blue indicator and spread it on a Petri dish. Add a drop of active starter at one edge. Put the top on and set it in a warm spot and watch the acid produced by the LAB spread across the dish.) No mixing, but the pH change will propagate just fine. And the LAB only grow on sugars so there must be enough to support growth everywhere.
My approach to assessing levain maturity was necessitated by a series of experiments that I was running with levain hydrations over 200% where the foam on the surface was a useless indicator of maturity and there was no rising and falling because it was all very watery.
Irrespective of whether yeast or yeast and LAB produce CO2, the fact is that they make it from sugars in the dough and that they make it in proportion to the sugars consumed in the process, so if you measure the amount of CO2 produced relative to the initial flour that you have used to feed it, then you have a solid estimate of where you stand in terms of maturity. For a 100% hydration starter where the rise and fall or foamyiness can be used to judge maturity, you can then weigh the starter when you think it is ready and use the weight loss as your target for levains mixed at unfamiliar hydrations.
The first test was to look at the weight loss of just plain water to make sure that I was not measuring evaporation. Sure enough, just water didn't lose a significant amount of weight while active starter did. And the number that I picked as the target for a mature levain was a loss of 2% of the weight of the added flour. This turns out to be good for levain hydration between 5% and 250% (nuts to soup so to speak).
So I ran a long series of experiments with three different starters under the same conditions and after they had been fed at different ratios, and at different temperatures, and had been refrigerated for different lengths of time. And my conclusion remains that 2% of added flour is a good number. Two percent also turns out to be enough such that for a few hundred grams of levain, the weight loss is a few grams and thus reliably detectable on a scale with 1g resolution (I typically see 3% loss after 12 hrs at 80°F for a levain build that is on the order of [28:220:220]).
Other conclusions from this series of experiments:
1. Refrigeration for 1 week has no effect on starter activity level and its ability to make a levain right out of the refrigerator.
2. After 2 weeks in the refrigerator, (@38°F) the starter is still losing weight at a nearly constant rate.
3. After 3 weeks in the refrigerator it is still losing weight though at a declining rate and it needs to be refreshed a couple of times before it returns to the activity level of a starter that was being fed every 24 hrs at room temperature.
4. Different starters exhibit different growth rates, but the differences are not huge - time to 2% weight loss (relative to added flour) may vary by a few hours (maybe a range of 11 to 16 hrs for fast and slow starters at a particular refresh ratio and temperature to reach 2%). You can run this experiment for your starter(s) and see what you see.
Refresh ratios that are too low (1:1:1) don't have enough flour in them to neutralize the acidity of the prior cycle and thus the replication rate of the LAB is suppressed and they stop replicating at a pH of ~3.8 anyway so repeating that error in a long series will run your LAB population down to a new operating point.
Similarly, refreshing before the starter has returned to the LAB/yeast numerical population ratio that you had in the beginning, will move your operating point toward lower yeast population over time.
Refreshing repeatedly at very high ratios (1:200:200) runs the risk that contaminants in the flour will be able to gain an advantage over the species you want and dramatically alter what you are growing. This is because flour is not sterile and you can run the numbers for any level of contamination you think appropriate. I had a problem a few years ago when I was refreshing at (3:100:100) and needed help from Mini Oven to get back on track, so this is an issue I am quite familiar with. You are better off to run refreshes at (3:13:16) for 12-16 hrs @ 78-80°F and then refrigerate for a day or a week (without penalty) until you want to refresh or need to make levain.
Can I just say that I LOOOVE this forum?
treesparrow, I get your joy :-) I feel like this is a special secret home for my bread geek self :-)
Doc, first off thanks for the detailed information. I would like to perform the starter migration test. To make sure I understand. Mix 5g flour, water, and a few drops of bromothymol blue indicator together, then put in a petri dish with a few drops of starter on a side. I assume we’ll get to watch the blue change colors as the acids from the starter migrate throughout the dish.
I looked up Brownian Motion and found the illustration. NOTE - I placed it on the very bottom, since it is distracting. Isn’t the Internet outstanding? If only I could remember the interesting things I learn.
Webster’s says, “Brownian motion definition is - a random movement of microscopic particles suspended in liquids or gases resulting from the impact of molecules of the surrounding medium —called also Brownian movement.”
This is a simulation of the Brownian motion of 5 particles (yellow) that collide with a large set of 800 particles. The yellow particles leave 5 blue trails of random motion and one of them has a red velocity vector. Resource - https://en.m.wikipedia.org/wiki/Brownian_motion
Dan
elevated this conversation. Thanks so much for your work and sharing it. So you think building a levain from an active starter that was retarded for less than two weeks can be refreshed with a single build of about 3:13:16 with little risk of altering that resultant levain culture as compared to the starter?
Thanks again.
If I am out of town or busy or lazy and my starters run for two weeks in the refrigerator, I generally can tell from how long it takes them to lose their allocated 2% of added flour weight whether or not I need to do a second refresh before I put them back in the refrigerator.
Doc, you wrote, “You don't need to stir a starter to redistribute the sugars or the yeast or the LAB.”
Would you agree that, although stirring is not necessary, it is helpful?
I haven’t made a practice of re-stirring or re-kneading my starters, but I am in the process of considering it. Do you see any value to that?
Dan
Unless you didn't mix everything when you initiated the cycle, there is no point in stirring it in the middle.
If you want to run the experiment, go to it. But I suspect that it will be a statistical challenge to extract useful data. The differences are likely to be on the order of the disturbances you introduce and batch to batch quantities, ingredients, temperature, and initial conditions won't be exactly the same.
Although I can’t imagine anyone disagreeing that stirring is necessary, it is difficult to accept that stirring or re-kneading will not reposition the food and microbes for increased activity. Is it also a wives tale that reshapng an over-proofed dough will impart more yeast activity to it?
Not trying to be argumentative, just expressing my thought process.
Dan
Doc, testing presents a problem. I think the very act of stirring or kneading will purge out additional CO2 that would throw the model off. Is this correct?
Assume that the LAB population density is within an order of magnitude of the stable end state (10E6/ml) and thus ~10E5 per ml. That makes the average distance between LAB something like 200 microns. Now figure out how much stirring you have to do to change that significantly. The Petri dish experiment should convince you that the LAB have a long reach over time without stirring.
Thanks, Doc. I plan to run the experiment for the fun of it.
Dan
Design the experiment and list the variables that you have to keep track of and the precision and accuracy with which you have the instrumentation to measure them. Now calculate the probability distribution for the experimental outcomes under two hypotheses:
1. stirring makes a difference
2. stirring does not make any difference
How many runs does it take to get a statistically significant difference between the two hypotheses in the face of your modeled experimental errors?
I think you will convince yourself that you don't want to do that much work.
This is where clever experimental design might have a big payoff, but I don't see a clean way to stir without disturbing the system.
This is too much of a blanket statement. It may be true for you in conjunction with your methods, however there is no reason why this feed can't be sufficient.
I think we can agree, a sufficient feed is one that pushes the pH up above 5.
1:1:1 (starter:water:flour) equates to a 33.3% inoculation and therefore 66.7% feed flour.
Take for example a Lievito Madre starter in the Panettone process. A typical feed ratio 1:0.5:1 = 40% inoculation, 60% feed flour. An even lower ratio yet the pH will be at 5+ after feeding. It really depends on timing and acidity.
A starter with a low titratable acidity (TA) that is fed every few hours works with a low ratio feeding pattern and it in fact encourages it.
Are you claiming this because the graph shows 2% loss after about a week?
“ 1. Refrigeration for 1 week has no effect on starter activity level and its ability to make a levain right out of the refrigerator.”
At what stage of fermentation is your starter when refrigerated to rest? Just after fed, upon maturity, ect..
I have 3 starters. At the beginning, I could tell them apart by smell. Each was very distinctive. Jack remains more distinctive than the others.They did behave differently in dough. These days, about 7-10 yrs into having the same 3 starters, they are less distinctive and smell/ behave only slightly differently from each other. Even tho they live in separate jars, they have "integrated" somewhat with each other. I still might be able to distinguish them by smell-I'll have to try that again.
3 distinctly different origins:
1. Jack was a dried,40 yr. old commercial packet of Sourdough Jack (typically sold to tourists at Fisherman's Wharf) from San Francisco found at a rural Wisconsin flea market in its unopened cellophane packet in the original dusty ceramic jar with the instructions and original pre-bar code label. Great starter! He woke up by crawling out of the jar when I added water! Needed a few "baths" to get rid of the rancid, white whole wheat flour he was dried in but cleaned up nicely!
2.Grape is from a fruit water starter I made 6 yrs ago from concord grapes in my daughter's yard. Morphed into a regular starter. Still has a wine-like smell (fainter over time) when it is at its best.
3. Knott is from a friend who had this starter maintained in her family for about 70 yrs. It is now about 80 yrs old. Very nicely balanced. She sometimes didn't feed it for YEARS. Kept it in the back of her refrigerator. When I asked about feeding, she was horrified that I wanted to feed it on a regular schedule. Her method was to add a spoonful to a sponge overnight and then proceed to mix and bake the next day, I guess. A pre-ferment,actually or a simple levain build.
I have always used unbleached AP flour for feedings, rarely measured feeding ratios, built other levains (whole wheat,rye) as needed, refrigerated, neglected, and sometimes rebuilt from tiny remnants so I can attest that sourdough cultures are pretty hardy. I have also dried and revived them without a problem.
I,too, love the mix of abilities on this forum-scientific researchers, hands-on experience, "citizen scientists" and home bakers making experiential observations. Very interesting question.
For me the biggest issue has been that although gluten development is not relevant, acidity is quite a game changer in my experience. A fresh or young levain will taste sweet and the lack of acidity helps in not degrading the gluten strands during the bulk proof etc. It will also result in mild bread, which the taste I am familiar with in my home town.
Dan, thank you for such an interesting and debate stimulating question. I look forward to reading this thread more in detail when I am back from work!
A levain that does not taste sour is probably telling you that you don't have much yeast growth (assuming that the seed starter tasted sour). The reason for this is that the LAB have a higher initial growth rate than the yeast and acidify the mix to pH ~3.8 then stop replicating (while continuing to produce acid). The yeast grows more slowly but is not inhibited by the acid and will continue to grow until the sugars are depleted. So the LAB population starts fast and levels off while the yeast starts slow but grows exponentially until limited by nutrient availability.
This is interesting. “the LAB have a higher initial growth rate than the yeast and acidify the mix to pH ~3.8 then stop replicating (while continuing to produce acid).”
If they quit reproducing but continue to produce acids, how come the PH doesn’t continue to fall?
Dan
I think it does continue to fall, only slower; and as is shown in this video by the time pH has fallen to 3.7 the gluten structure has been so thoroughly destroyed that no elasticity or extensibilty is left, the dough is by then completely useless for baking. So that is a range we don't normally get to see.
https://www.youtube.com/watch?v=vsCpdCsJFr4
(I know it's in French but you can still compare the two doughs, the sourdough one and the bakers's yeast one, watch the sourdough one degrade and the corresponding measurements for both on the pH meter ;-)
Since all of the acids in sourdough (lactic and acetic mostly) are weak acids, the relationship between acidity (molarity) and pH is governed by Kpa. It takes a lot more acid to go from pH 3.8 to 3.7 than it does to go from pH 5.0 to 4.9. This is why you just can't use pH as a proxy for "sour" since what you taste is the molarity of the acid.
By the way, the first weak acid to form in sourdough is carbonic acid which results from CO2 dissociating in water.
As an aside, this is where it is perhaps appropriate to compare the molecular weight and vapor pressure of lactic and acetic acids and observe that because it has a lower molecular weight, and thus a lower vapor pressure, you can smell acetic acid while you cannot detect lactic acid with your nose. So when you smell sourdough bread, you are detecting only the acetic acid..
Doc, I don't get the connection, "A levain that does not taste sour is probably telling you that you don't have much yeast growth ". I though that sour flavours are produced by acetic and lactic acids and those are produced by LAB not yeast.
Also, are you building a levain from a starter using one build or three?
if the levain is not yet sour then it is an indication that the LAB have not yet completed their growth cycle and generally the yeast are slow enough that they don’t reach their original population density until well after the LAB have stopped replicating. So - no sour means probably not yet much yeast either.
And generally I build a levain in one shot unless I need a huge amount
“if the levain is not yet sour then it is an indication that the LAB have not yet completed their growth cycle and generally the yeast are slow enough that they don’t reach their original population density until well after the LAB have stopped replicating. So - no sour means probably not yet much yeast either.”
I always thought that if the culture was allowed to buildup acids, the yeast were losing ground. But as I think about this, we are told that as acids increase in the culture causing the PH to lower. And at ~3.7-3.8 the LAB quit reproducing but continue to produce their byproducts. But the yeast are not hindered by low PH.
Please elaborate what is going on during the maturation pahse of both the yeast and LAB.
You have lots of experience with the 2% weight loss of total flour in culture. At 2% loss are your starter slumping (receding)? Please discuss a few culture hydrations in respect to the visuals of the mature starter.
But at the making of the starter and how yeasts only mature once the starter is acidic and stable. Just like the yeasts do better, when making starter, once the environment is acidic enough then so to when maintaining a starter or building a levain. They also talk about the LAB always outnumbering the yeasts by a lot!
https://www.discovermagazine.com/planet-earth/the-biology-of-sourdough
At the end of the day to get a strong starter is to nurture a stable starter. A stable starter symbiosis is about 100:1 in favour of the LAB.