Hi All
I am hoping someone can help me get my head around the following concept:
If I maintain my starter at a constant temperature (say, 20c), I understand that I am creating a population of bacteria, yeast etc that thrives at that temperature. So, is changing the environment of my starter (e.g throwing it into a batch of dough at a different temperature) likely to kill off a large part of that population and limit the efficacy of my starter (subject to the extent of the temperature difference)?
If I am trying to minimise the fermentation time of my dough, would it make more sense to maintain my starter and my dough fermentation temperatures as close as possible? My hypothesis is that, all else being equal, a starter maintained at a similar temperature to the dough fermentation temperature will ferment the dough quicker than a starter maintained at a different temperature. This is because the organisms in my starter have evolved to populate at that temperature to a greater extent than they would populate at say, +/- 10c.
I'm building a new starter at the moment and will obviously experiment when it's ready. But I was hoping for some techncal explanation to satisfy my curiosity in the meantime.
Thank you :)
The starter temperature is optimal for reproduction of certain microbes. You maintain your starter to keep multiplying their numbers. For the microbes the only meaning of the word to 'thrive' is to reproduce as fast as possible, to have offspring.
Dough temperature is optimal for bread taste, i.e. for certain acids and other substances that those microbes produce at certain temperatures. It has nothing to do with reproduction, with multiplying their population.
This difference is very obvious in yeast factories, where the only goal is to reproduce yeast which is later used in bread dough at very different temperatures. Yeast is multiplied at 30C in liquid sugary water which is churned, well aerated - the optimal conditions for reproduction, for multiplication of yeast cells. This yeasted water is 'the starter', the place where yeast is multiplied.
For the sourdough microbes these two temperatures are different: optimal for reproduction temperature and optimal for metabolism temperature.
If they reproduce the best, let's say at 30C, then they work the best (produce most acids, gas, alcohol) best at 32-33C or even at 40-45C when their metabolism is the fastest. Which, again might not be the goal of the baker. If you want sharp and biting sour taste and aroma, then lower the temperature to force them bacteria to produce acetic acid. If you want milder and softer acidic taste, then rise the temperature, to force them to produce more lactic acid. Some bakers vary the temperature to achieve the bread they want, even if it means not the optimal temperatures for the microbes.
Normally, sourdough microbes do not reproduce inside bread dough, at least, it is not the goal. We only want them to work, to produce a certain amount of acetic or lactic acid in certain proportions, a certain amount of gas, to give bread volume, taste and aroma.
Thanks for such a prompt and thorough response Mariana.
So assuming i had two starters: one maintained at 18C, the other at 28C. And I then used these starters for two separate batches of dough both fermented at 30c. Would you expect the dough fermented with the 28c starter to ferment faster than the 18c starter batch because it has more microbes that thrive around 30c? On the other hand, would you expect the taste of each bread to be similar considering they metabolised at similar temperatures?
My guess is I'm oversimplying things but would be grateful for your thoughts.
No, muso, I would not expect that.
On one side, if you use recipes for starters from professional bakers, they are all similar in their performance, have the same gassing power and acidify bread dough with similar speed. I tried their recipes for 18C starters and for 28C starters and inside bread dough they perform the same at 30C, even though the starters smell and look different , with different microflora. In that sense bakers can exchange bread recipes among themselves and they will work.
On the other side, starters created by amateurs are all different, even if created from the same ingredients at the same temperatures, some are slow and some are fast. They pick up a huge variety of sourdough species from flour and hands and huge variety of strains of the same species. They truly are unpredictable. You can be lucky and pick up fast species or strains at 18C and unlucky and pick up slow gassing and slow acidifying species and strains at 28C, the difference in "speed" between them can be fifteenfold, it truly is unpredictable.
It's the same as differences between humans, we are all created at 36.6C, temperatures of healthy human bodies of our parents and our own, but some of us are born fast workers and others are slow, it's unpredictable.
But professional bakers use recipes that select sourdough microflora with standard performance, like recruters for jobs. Their starters and bread dough reliably double in a couple of hours at 28-30C, because it's their business, their income depends on it, they cannot wait for 30 hours instead of 2 hours for their starter or dough to double, the way homebakers do, just because they picked up slow gassing species of yeast from their flour.
Some starters by nature are very sour, others are very mild, temperature has nothing to do with it, so no, I would not expect that two starters would give the same taste at 30C.
Thanks again Mariana
I have a proofing box that gives me the ability to hold my starter at a relatively consistent temperature. I have to set it to something. So was wondering whether I should use the same temperature I intend to ferment my dough (around 30c) or something else. It is currently 20c. I do this to reduce frequency for feedings that I'd expect than if I were maintaining at higher temps. I want to ferment dough warmer because I want less sourness and faster fermentation. It appears my decision to maintain my starter relatively cooler should not adversely affect my goal to ferment dough warmer.
My takeaways from your posts are as follow:
- fermentation speed of dough will primarily be dictated by fermentation temperature assuming your starter is well populated. Whether that starter was maintained at higher or lower temperatures is not itself a significant factor.
- 'maturity' of the starter (in the context of the population of micribes since last refreshment) will affect fermentation speed, if the starter is a healthy one.
- 'Taste' is probably, maybe, not necessarily, influenced by the fermentation temperature of the dough (not starter maintainence)
Or, as an alternative to all of the above:
- It depends, try and see :)
I understand. We all choose recipes that suit us, our overall schedule. At 18C you would feed your starter once in three to five days, at 30C - once a day.
Although, of course, there are recipes for feeding once a day at 18C and 3-7times per day at 30C if you wish to create a starter from scratch in 24hours and bake many batches of bread around the clock which requires lots of feedings per day..
The takeaway from all of the above is twofold,
(1) it all depends on the recipe that you use, temperature is just one element of many in the recipe of a starter, choice of flour and other ingredients in your starter, proportions of feeding, how stiff or how liquid your sourdough is... they all play a major role.
(2) there is an element of unpredictability, of surprise, it's like groping in the darkness, you never know beforehand what you will catch.
Good luck with creating a good starter and baking great bread!
Thanks again Mariana :)
I have been making the exact same recipe over and over for the last 2-3 months, and it has allowed me to observe the effect the starter has on the bread. For the first 10 loaves, I did not get a lot of leavening, but I had a lot of sour flavour (which I enjoyed.) I then made a focused effort to strengthen my starter, and it now gives me huge leaving power, but not even a slight hint of sourness. I wish I knew how to tailor the LAB/AAB/Yeast balance to give both good lift and more acid, but I don't. My starter and my bread both ferment at ~19-20°C. Bulk fermentation seemed to perform the same whether it was my old "acidic" starter or my new "yeasty" one. (Actually, that's not true, my acidic starter would turn my dough to mush in short order. I had to be careful to cold retard it before that happened. Not sure if you can get anything out of this, but I thought I'd share my observations.
Hi Mark,
I would be curious to know what you did to "strengthen" your starter? You mention you transitioned from an "acidic" to a "yeasty" starter so my impression is that you have changed the temperature and/or the frequency that you refresh the starter.
I paid closer attention to the rise and fall of the starter and was careful to refresh just as the dome was falling. As a consequence, the rise and fall cycle became more rapid gradually. I then increased feeds from 1:1:1 to 1:2:2, then 1:3:3 and finally 1:5:5. After 7 days, my starter was performing much faster, and I used 1:3:3 or 1:5:5 to maintain a once per day feeding schedule. Prior to this change, I would feed it 1:1:1 or 1:2:2 every 24 hours, and it would often sit completely depleted until feeding time around 11 pm. But it was very slow to leaven a bread, and would often breakdown the gluten network. If I let it bulk too long, it would become soup. But to be clear, I'm sure there were other things I was doing wrong, I really didn't have a good understanding of bulk fermentation or the common progress markers. But I can tell that my starter works much differently now. The feel of the dough at the 3-4 hour mark are completely different now, it's much more puffy and workable now.
This is how my starter behaved prior to "fixing" it: https://www.youtube.com/watch?v=USra9-DnNP8
Thanks Mark. I am pleased to hear you were able to find an approach that worked for you. I look forward to go through a similar process as my starter develops.
Different temperatures at which your starter/levain is maintained will, as Mariana explained, either increase or decrease the rate of fermentation. But additionally - and this goes to flavor - the temperature affects the lactobacilli in the starter in significant ways. At “room temp,” say 20 Celsius, the lactobacilli produce mild lactic acid. However when refrigerated/retarded, say at 5-6 Celsius, they produce acetic acid, giving breads a distinctive sourness which is lacking in sourdoughs fermented & proofed at room temp.
I found the below chart online and believe it's a good guide after you adjust it to your sourdough and flour. I mean, better than working totally blind.
It's just a spreadsheet table with no function, would love to see the math model behind it.
https://docs.google.com/spreadsheets/d/18jeeaXbu61j7D2d1bIynj8eJUp5qrXpq-oq-HjkBZj8/edit#gid=0
BTW: Acidic vs. Yogurty I adjust with the water content > https://www.the-bread-code.io/recipe/2021/10/24/all-you-need-to-know-stiff-liquid-regular-starter.html