Warning – Warning – This Post Is Incredibly Long – Warning – Warning
Some 25+ years ago, when I was living in Connecticut, I started baking bread for the first time. I was introduced to the Zen of bread by way of The Tassajara Bread Book by Edward Espe Brown. After working my way through several different types of bread, I decided to try making a commercial-yeast-free sourdough starter with visions of hefty round fragrant loaves and tart pancakes dancing in my head.
His approach to making a sourdough starter with wild yeast was to take a soured food like rice or cereal, and mix it with some whole wheat flour and water to make a paste that you allow to sit at room temperature for 3-4 days until it starts to bubble and smell sour. Simple enough. Using some leftover rice I had, I proceeded to make my paste and promptly had a jar full of rot. Discouraged, I decided that sourdough was not for me.
In hindsight, I realize that I didn’t understand the process involved in developing a starter for sourdough bread. I don’t think that his process was the problem – my execution of the process was the problem.
Fast-forward to this last spring. In my baking class, we paid lip service to sourdough starters and the processes necessary to make breads using natural yeasts, but the way classes were scheduled prevented us from attending to the upkeep that a proper sourdough starter requires.
Now, I have found numerous magnificent treatises on bread that cover the care and feeding of sourdough starters at great length. Armed with a better grasp of the science of pulling yeast out of thin air, and having plenty of time on my hands, I feel confident enough to embark on a new sourdough adventure.
For this first blog posting on the subject, I want to present my own approach and results in developing a successful sourdough starter culture. This will be a long post since I want to address a lot of the nagging little details I dealt with – things I wish someone had mentioned in the various books I consulted.
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Background
Superficially, it seems like different authors present wildly different approaches to their cultivation of wild yeasts – but underlying each approach are just a few common threads that are important.
Commercial yeast is specifically Saccharomyces cerevisiae. The wild yeast that is cultivated in sourdough starters is a different species of yeast called Saccharomyces exiguous. Saccharomyces cerevisiae is fast-acting and aggressive. Its wild cousin Saccharomyces exiguous is slow-acting. This wild yeast lives comfortably in an acidic environment that is inhospitable to commercial yeast.
Saccharomyces exiguous can be found in the air around us and is also responsible for the whitish frosty-looking film that is visible on fruit like grapes and plums and on cabbage. This wild yeast is also plentiful on wild grains like wheat and rye and exists in a dormant phase in whole grain flours.
The desirable sour flavors in sourdough do not come from the yeast activity, but from activity of lactobacillus bacteria that produce lactic acid and acetic acid over time. When making a sourdough starter from scratch, the wild yeast cultures will develop much sooner than the acids from the lactobacillus bacteria. While it may be possible to use a starter to make bread in just a few days, it typically takes weeks for the characteristic sour flavors to develop to the point where you can taste them distinctly in bread.
The balance of the lactic and acetic acid produced by the lactobacillus bacteria can be controlled by manipulating the consistency and temperature of the starter culture. Cooler and less hydrated starters are conducive to the formation of acetic acid – which has a sour, vinegary taste. Warmer and more hydrated starters are more conducive to the formation of lactic acid – which has a more mild, buttermilk-y taste.
A sourdough starter is not a static thing – it is a living culture. Establishing an appropriate culture depends on a variety of factors – and getting a culture to the point where it is useful for flavoring and rising bread is a lesson in “let’s not get ahead of ourselves” – a perfect example of the cart/horse phenomenon.
The road to a thriving sourdough starter culture really starts at the intersection of flour and water – this inauspicious pairing starts a biological cultural evolutionary process pointed in the direction of a tasty bread leavening goo.
I conceptualize the acculturation process as having five stages or phases:
(1) Inoculation – Water and flour are mixed which sets-off a ton of microorganism activity – wild yeasts and bacteria feed and produce byproducts – among these byproducts will be carbon dioxide and acidic waste.
(2) Initial Acidification – The byproducts of the initial microorganism activity begin to acidify the mixture which, in turn, produces an environment that is more favorable to some organisms and less favorable to others.
(3) Development – As the mixture continues to acidify, a symbiotic relationship starts to develop between the lactobacillus bacteria and the wild yeast in the culture – the bacteria generate sugar by breaking down the carbohydrates in flour and the yeast converts the sugar to carbon dioxide and alcohol. Slowly, the bacteria and the yeast will dominate the roster of microorganisms in the culture – their numbers in the developing culture allows them to work very quickly whenever new food is available for consumption.
(4) Stable Life Cycle – Eventually, the culture will fall into a predictable life cycle that revolves around feeding – basically, there will be sufficient yeast and lactobacillus bacteria swarming in the culture that they can exhaust the available food supplied by an equal amount of flour/water within a 12-24 hour period.
(5) Ongoing Development of Characteristic Acidic Flavors – As the lactobacillus bacteria continue to develop in the starter culture, the abundance of lactic acid and acetic acid in the starter and the ratio of these acids will generate the complex characteristic tang that is so inviting in sourdough bread.
Note – this is my own personal conceptualization. It is the way I tried to make sense of the progression of flour and water to a functional sourdough starter. Sourdough starter, at its core, is just flour + water + time. These phases I have listed are my attempt to describe how to measure time in the world of sourdough starter culture.
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Approach
Gathering Ingredients – My goal was to jump-start exposure to desirable wild yeasts using every conceivable source: (1) whole grain flours, (2) organic grapes, cabbage, and raisins, & (3) airborne (all of which were deemed in some way fundamental in different professional bread-baking texts). The underlying idea I had here was that a culture that starts out with greater exposure to good wild yeast will stand a better chance of progressing quickly to the point of being a useful and healthy source of lift and flavor for bread.
There was considerable agreement within my sources that rye flour should be the go-to flour when developing a starter. Apparently, cultures develop and stabilize more quickly with pure rye starters than with other flours. Point taken. I decided to start things off with whole grains, but went with half-rye and half-wheat simply because rye flour with water makes a notoriously difficult paste to work with – sticky and contrary and not-at-all fluid – I figured that some wheat would make a starter that was easier to work with.
Whole Grain Wheat Flour.
Whole Grain Rye Flour.
Organic Grapes – Unwashed.
Detail – Wild Yeast on Grapes.
Organic Cabbage – Unwashed.
Detail – Wild Yeast on Cabbage.
Open Window – Maximizing Exposure to Wild Yeast in Air.
Spring Water – Chlorine is the Enemy.
Important note – chlorine really IS the enemy here. I had actually started this project/process a week earlier and decided to use some Brita-filtered tap water after a few days (I had run-out of spring water) – it shut down my culture almost completely. I will address what I did with that culture at the end of this post – it has a happy ending.
I decided I would feed and maintain my new culture with spring water indefinitely – hence the huge jug in the picture. So, especially during the critical beginning stages of developing a sourdough starter culture, it is important to avoid introducing anything by way of your water that could be toxic to the microorganisms in your mix.
Organic Raisins – Made From Organic Grapes – Maximizing Initial Exposure to Desirable Wild Yeasts.
Note – One of the books I consulted seemed quite convinced that there is good wild yeast present on the surfaces of organic raisins: yeast that remains a companion to the dehydrated fruit from its days as juicier organic grapes. Sounded legit’ enough – and my plan was to do everything in my power to snag as much wild yeast as I can from the start. Hey, the idea of harvesting (stealing) wild yeast from raisins seemed a bit odd, but not as odd to me as the idea of using wild yeast growing on cabbage.
Stage 1 – Inoculation – Following the direction of nearly every bread baking resource I consulted, I started my sourdough starter using equal parts (by weight) of whole grain flour and spring water. I also tried to jump-start my starter by exposing it, initially, to as many sources of wild yeast as I could cram into my mixture.
I started out by soaking 2 oz. of organic raisins in 8 oz. of spring water for about an hour.
4 oz. whole grain rye flour + 4 oz. whole grain wheat flour.
Flour, raisin water, 4 oz. grapes, 2 oz. cabbage, whisk, strainer (to catch the raisins).
So, right from the start, I combined as many potential sources of wild yeast as I could manage at once: the whole grain flours, the raisin rinse-water, and the unwashed grapes and cabbage.
This initial exposure of the mix to sources of desirable microorganisms is what I think of as the inoculation phase.
Flour + raisin water.
These form a sticky paste.
Add fruit and cabbage.
Mix thoroughly.
Finally, I set the mixture in an open window for 2 hours in hopes of inviting any local wild yeast to the mixture.
That’s my other source for wild yeast: the air. My goal was to invite yeast into the starter from every conceivable and reasonable source. If there is any wild yeast visiting our neighborhood, it is now part of the mix.
Cover loosely for an additional 10 hours.
Now, there should be sufficient yeast and bacteria available to drive the mixture in the direction of a successful sourdough starter culture. My next step was to separate the batter-y dough from the fruit – easier said than done.
I placed a strainer inside a large mixing bowl.
Then I rinsed the mix with 8 oz. of spring water.
Using a spatula, I worked to press the flour/water mix through the strainer.
Rinsing with 2 oz. more spring water.
This is the best I could do to separate the flour and water from the grapes and cabbage.
Removing the grapes and cabbage left this in the bottom of the strainer that I transferred to the mixing bowl.
The final inoculated starter and rinse water mix.
Add to the mix: 4 oz. rye flour + 4 oz. wheat flour.
Mix.
Windowsill for 2 hours (again for exposure to any local wild yeast and bacteria). Then cover and allow to sit overnight.
Summary: At this point, 24 hour had passed. I started with 8 oz. raisin/spring water and 8 oz. rye/wheat flour and a bunch of grapes/cabbage laden with wild yeasts. I let that sit for 12 hours, then separated-out the flour/water by rinsing the grapes/cabbage – I then added additional rye/wheat flour to maintain equal parts of flour and water by weight and let that sit for another 12 hours.
Hindsight: To kick-start my inoculation, I soaked the grapes and cabbage in my flour/water mix. I did this to expose my culture to the naturally occurring yeast bloom on the grapes and cabbage. That was messy and it was difficult to separate the mix from the grapes and cabbage leaves. Perhaps I could have accomplished this more simply by agitating the grapes and cabbage in my start-up water (along with the raisins) to dislodge the yeast into the water BEFORE involving the flour. If I were do start this process over again, I would undoubtedly combine the raisins, grapes, and cabbage in a larger quantity of water and shake it to dislodge the available yeast – then use that yeasted water as my initial feeder water when I started my culture.
I transferred measured quantities from my inoculated mix into two jars – one with 8 ounces of my starter and one with 4 ounces of my starter.
Why two jars? Well, I wanted to see how differently the culture would develop with unbleached bread flour as opposed to my rye/wheat mixture so I kept a smaller culture going with feedings of bread flour and spring water. Spoiler alert – it developed at a snail’s pace relative to the whole grain starter.
To the larger jar – I added 4 oz. rye/wheat flour and 4 oz. spring water (doubling the amount). To the smaller jar – I added 2 oz. bread flour and 2 oz. spring water (doubling the amount). Whisk vigorously to combine.
Another 2 hours on the windowsill of an open window – again trying to maximize exposure to airborne wild yeasts.
Cover for the remainder of a 24 hour period.
Inoculation proof of concept here – you can see bubbles from carbon dioxide in the mix and the baby culture has expanded quite a bit (I used rubber bands to show “before” and “after” rising).
For comparison, here is the culture I fed with bread flour – you can see some bubbling but the activity is nowhere near the amount seen in the whole grain culture.
So, after 2 days, we end the inoculation stage with evidence of microorganism activity.
Most of the progress of a sourdough starter culture is identified by sight and smell. During the inoculation, you can SEE bubbles from carbon dioxide. But even at this point, there are SMELLS you should be conscious of – my culture smelled a little cardboard-y (probably from the rye), a little like leather (which books say is common), just a little yeasty, and just a little bit sour. There were no bad of off smells.
Stage 2 – Initial Acidification
Well that was exciting. Now comes a boring phase. The microorganisms in the culture need time and routine feedings while the balance of power shifts. For a while, the carbon dioxide activity will grind to almost a halt (a lot of the initial gasses came from a variety of sources – not all of them desirable in the long run – those sources will eventually die-out as the culture acidifies).
Feeding – The process of feeding goes like this: after 24 hours, stir your culture vigorously and remove about half of it (eyeball it). Then replace what you removed with equal parts by weight of flour and spring water. I always add the water to the reduced culture first and stir to distribute the culture thoroughly before adding the flour – this makes sure the culture has the best exposure to new food (flour) as possible.
Feeding Schedule – Many books recommend feeding the culture every 12 hours. My own thought is that there is no reason to feed it that frequently unless there is ample evidence that the organisms in the culture are consuming all the available new food from the flour in less than 24 hours. Even with a mature culture now, I have found no reason to feed on a twice-a-day schedule. And let’s face it, you’re going to be throwing away PLENTY of flour as it is without doubling the process.
Stir-up the bubbly starter to mix and deflate.
Remove half of the culture from the jar – just estimate here.
A reminder here – at the end of the second day, the larger jar had 16 oz. of culture. After removing about half of that, I had roughly 8 oz. left. To replenish that amount, I added 4 oz. spring water and 4 oz. rye/wheat flour. I always estimated what I removed, but I weighed-out the flour and water to keep the ratio of components equal.
For my feeding routine, I maintain equal parts by weight of flour and water because, once I use my starter to bake bread, I can construct the flour/water ratio in my dough easily and precisely.
4 oz. spring water. Stir vigorously.
4 oz. rye/wheat flour.
Stir vigorously.
I also scrape-down the sides of my jars so I can see what is happening inside. I continue to mark the level with a rubber band so I am better aware of any expansion of the culture.
For the first week of this, I continued to leave my jars open in the windowsill for 2 hours each day.
As you can see, there is some activity here, but it is greatly reduced from what we saw the second day.
A few bubbles evident on the surface of the culture.
So, after the third day, it looks like the starter has lost ground. But during this phase, as the culture begins to acidify, some of the organisms that created the initial commotion are starting to die-off – that’s a good thing. So we haven’t lost ground.
You should still see some evidence of carbon dioxide formation – bubbles. The culture might swell some over the course of the 24 hour cycle but it probably won’t swell much at first. But you SHOULD start to notice changes in smell – specifically, the culture should begin to smell a little acidic. My culture started to smell like lactic acid first – a lot like buttermilk. It took a little longer for me to notice the distinct vinegary smell of acetic acid.
Every 24 hours, keep repeating the remove-and-refresh cycle. Discard half of your culture and replace it with equal parts by weight of flour and water.
After 5 days, there is more rise in the culture I am maintaining on rye/wheat flour. No real rise in the culture I’m raising on bread flour. Both cultures, though, smell distinctly acidic.
Again, the stages I am presenting here are not some designations tied to the baking community – they are simply the way I think about the progression of a starter culture. While I will be showing you the progress of my culture on certain days, I don’t think of the days as representative of the stages – the sights and smells associated with the culture should be what alerts you to your progression. Your culture will progress at different rates based on a whole host of different factors: temperature of your kitchen, temperature of the water you use, brand and type of flour you use, time between feedings, and the strength of your culture at any given time.
As for “acidification,” I figured that my culture was acidifying when it started to smell noticeably acidic. No more, no less.
Stage 3 – Development
Nothing about the care and feeding of the culture changes from this point forward. Every day, I removed about half – then I replaced that with equal parts by weight of flour and water.
Here, after 7 days, you can see that the rye/wheat starter culture is showing increased activity – not so much with the bread flour culture.
The go-to standard for identifying when the culture has developed into a mature starter is “doubling” – seeing that it doubles in volume during its daily cycle. You can see in the photograph above that my rye/wheat culture had doubled, but it took a full 24 hours to do so. That’s good sign, but not a sign that the yeast had multiplied to the point where they could act with sufficient vigor in a bread dough to lift the bread to acceptable levels.
Stage 4 – Stable Life Cycle
The yeast and lactobacillus bacteria will continue to multiply in the culture. After my culture finally doubled in size over a 24 hour cycle, each day after that I noticed that it was expanding more and more quickly following my morning feeding.
Day 10 for me – this is what my starters looked like after about 2 hours.
Just a few days before, the culture was showing impressive activity over time; over a LONG time. Slowly, but surely, I saw the activity in the culture expressed more aggressively – in the photograph above, you can see that my rye/wheat culture was well on its way to doubling in size only a couple hours after feeding.
Here’s a top view of the rye/wheat starter culture after 8 hours on the 10th day.
As much as my many books would have had me believe that in less than a week my starter would be as active as one from a professional bakery, my reality was quite different. Ten days into my starter, it had shown all the right sights and smells of being a healthy culture but I didn’t think it was ready for prime time baking yet.
Let me emphasize again that a sourdough starter culture is going to develop at its own pace – a culture can’t read a calendar.
Day-after-day I watched as my nascent culture fell into a recognizable pattern of behavior indicative of a stable life cycle. Just after the end of the second week, the culture began to peak in its expansion after only about 5 hours – it was more than doubling in that time. The acidic smell of the starter had grown strong and more noticeably acetic.
Ultimately in a sourdough starter, the yeast and bacteria are present in such numbers that they can act quickly to convert new food to carbon dioxide and to desirable sour-tasting acids. At some point, the culture stabilizes into a reproduction life cycle – new food is added…followed by a flurry of activity…followed by the starter growing to at least double its size…followed eventually by the exhaustion of the available food where carbon dioxide production starts to shut down and the starter loses lift and is ready for new food again.
On day 15, my rye/wheat culture has more than doubled in 6 hours.
For that same culture – the next day, you can see there are almost no bubbles on top – an indication that carbon dioxide production has ceased.
Stage 5 – Ongoing Development of Characteristic Acidic Flavors
My culture stabilized in just over two weeks. There was ample evidence by then that yeast were plentiful enough to generate carbon dioxide quickly and vigorously – that’s what you’re looking for in the interest of rising bread dough. But as I mentioned way back toward the beginning of this post, the strength of the lactobacillus bacteria in the culture takes longer to develop than the yeast.
I want to make strongly sour sourdough breads – San Francisco sourdoughs. And after the third week of my daily culture feedings, the smell of the acetic acid in my culture was the dominant smell. After three weeks, there was no question in my mind that I had usable and VERY flavorful sourdough starter culture.
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But my story doesn’t end there. Well…actually…it doesn’t end at all at this point (I still haven’t used my culture to make bread yet – I’ll be working on that later this week).
I still need to sew-up a few loose ends from my journey that are of interest here.
What Happened To The Bread Flour Culture?
After the second week of daily feedings, the culture I was feeding on bread flour wasn’t showing the aggressive yeast activity that the rye/wheat culture was showing – but it had a wonderful aroma (more lactic acid than acetic acid – but a smell that seemed to imply that the lactobacillus bacteria were multiplying, even if the yeast were not).
Some evidence of carbon dioxide after 2 weeks – no real rise of the culture though. Great aroma.
Since my rye/wheat starter was performing so well, I had nothing to lose with the bread flour starter so one day into the third week, I decided to feed it with rye/wheat flour instead of bread flour.
In just 24 hours, my failing culture took hold of the food in the rye/wheat flour and blossomed. Notice the vigorous bubbling from yeast activity and how the culture has risen to nearly the rim of the jar.
Perhaps if I had fed my smaller culture on rye/wheat flour for a few more days before transferring it to an all-bread-flour diet it would have given the yeast more of a chance to establish itself from the beginning. But after only one day of feeding on rye/wheat, that culture seemed to do quite well on just bread flour in subsequent feedings.
There was still a difference in smell between the two cultures. The rye/wheat culture smelled much more strongly of acetic acid and the bread flour culture smelled like the milder lactic acid. Both smelled great though.
What Happened To That Initial Culture That I Almost Killed With Filtered Tap Water?
Our tap water here is heavily chlorinated. You can even smell some chlorine after the water has been Brita-filtered. Whatever chlorine was left in the filtered water I used in my original culture knocked the wind out of its sails. I could see that the culture wasn’t completely dead, but it was going nowhere fast.
Again, in a situation where I had nothing to lose, I bought some more spring water and decided to continue maintaining my damaged culture. While I started my process over with the cultures documented in the pictures above, I continued to feed my ailing chlorine-poisoned culture haphazardly – I removed half of the culture daily but didn’t bother measuring exact quantities of flour or water that I added – I also threw-in different flours each day: maybe some wheat, maybe some rye, usually some bread flour, and I finished-off a bag of sprouted wheat flour that wasn’t finding a purpose anywhere else.
Having been burned by chlorine once, I used only spring water in the maintenance of my experiment in remediation.
My solemn vow: I will never take another chance with tap water – in my sourdough starter culture or in the breads I bake with them. It’s just not worth the risk.
After two weeks of feeding, my once ailing culture was showing signs of life – by sight and by smell.
After three weeks, my once chlorinated culture was healthy and vibrant.
My goal in feeding the sick culture was not to prove that it could be revived. Every source I consulted on sourdough gave me faith that these cultures are remarkably resilient. No, I was more interested in watching (and smelling) the progress in a culture where daily maintenance was lazy – no pesky weighings and measurings. Not everyone can be (or wants to be) committed to a routine of precise cultural upkeep – and my results with this culture would suggest that it’s OK to be that way. I think that as long as you maintain the cultural environment as a think paste, the magic of the microorganisms will take care of itself.
Remember that the reason I am so fastidious about using equal parts by weight of flour and water has to do with anticipation of how I will measure-out ingredients when I bake bread. The ratio of liquid to flour in bread dough is an important consideration when planning how your bread will bake-up. Knowing that whatever starter goes into the dough will be half flour and half water, it will be easier to prepare a dough to precise specifications of hydration (liquid content).
My Final Stable Culture
After of month of daily feedings and more looking and smelling and photographing than is probably normal, I had three cultures on my hands: (1) my thriving rye/wheat flour culture (which smelled strongly of acetic acid), (2) my bread flour culture that blossomed once I fed it some rye/wheat flour (which smelled more of lactic acid), & (3) my Franken-culture that I brought back to life and fed with bits from my flour graveyard. Surely the rye/wheat flour culture would the culture of preference as a leavening and flavoring agent for bread dough – but not wanting to choose one child over another, I mixed all three of my disparate cultures into a single mega-culture that I allowed to sit for 24 hours before extracting 8 oz. to use as my permanent sourdough starter culture. To that 8 oz., I added 4 oz. of flour and 4 oz. spring water – then I continued my 24-hour remove-and-replace feeding cycle every day.
My final working sourdough starter culture plays well now with feedings of any type of flour (though it seems more partial to the rye flour) – it should be suitable for making just about any kind of sourdough bread I desire. That’s my next project. I’ll cover the preparation and baking of my first sourdough loaves in a separate post.
If you’re thinking about starting your own culture from scratch, the rye/wheat flour and spring water approach worked very well for me. Using all whole grain rye flour probably would have been superior, but more difficult to work with (soooooo sticky) – using all whole grain wheat flour probably would have been OK too but might have taken a little longer to develop. Moral: best to start your sourdough starter culture with whole grain and spring water. Once the starter is fully established, the conversion to other flours should not be a problem.
I wound up with two extra cultures – an ailing one from an injudicious decision to use tap water (hey kids…don’t use tap water…use spring water) – and one that served as an experiment with bread flour (which suggested that using rye/wheat flour was the better way to develop a healthy starter). Though I combined my three cultures as a courtesy to all the cultures involved, my rye/wheat flour and spring water culture was the clear procedural winner in the one-jar-one-culture world we want to live in.
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Let me leave you with a few pictures of my final culture:
My final culture – just after its morning feeding.
After 2 hours.
After 6 hours.
After 24 hours – you can see where the starter has fallen-back as carbon dioxide activity has nearly ceased.
Waiting to be fed.
My journey to this point has taken a month. And a LOT of flour. But the time has been well spent. I’m very happy with my sourdough starter culture – watching the daily rise-and-fall of my wet living dough – being greeted each morning by the bracing smell of acids that have me anticipating that puckering tang of west coast breads.
I apologize for the agonizing length of this post, but it represents the details that played-out over the span of four whole weeks. I wanted to give it the full attention I thought it deserved.
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