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Demystifying Sourdough Bread Baking
Basic Understandings
If you start baking sourdough bread (and you really should), and you use the google to learn about how to do it, you will quickly find that there is both a lot of information out there on baking sourdough bread, and also a lot of conflicting information out there about baking sourdough bread. I think that this is because the process of baking sourdough bread has a lot of interdependent and invisible variables involved which collectively affect the results a lot, and that makes it a bit mysterious. So, just like they do with the mystery of existence itself, people evolve various beliefs and rituals in the face of their lack of knowing. And just like there are many different ways to live and to understand the tremendum in which we find ourselves, there are also many different ways to successfully bake a loaf of sourdough bread.
The words below are how I understand sourdough bread baking. This understanding is the result of a few years of my reading and watching and absorbing other people’s beliefs and rituals, coupled with baking loaf after loaf and trying this and that and paying attention to what seemed to matter and what seemed to not matter in the results I got. I don’t claim that these words are The Truth of sourdough bread baking, or that they describe the One True Path to sourdough bread bliss. This is just what works for me and makes sense to me. So here’s some stuff I have learned (really, mostly unlearned) in the process of moving from a beginner to an intermediate sourdough bread baker.
Ignore the Word ‘Recipe’
Although they tend to be written as though they are, sourdough bread recipes are not like other recipes where you follow an exact procedure using exact measurements with exact temperatures and exact timings. You can treat them like that (and most people do), but if you do, you will not get consistently good results. Sometimes your bread will come out great and other times it will come out not so great. Sometimes a nice rise and “oven spring”, sometimes a dense flat brick or “frisbee”. And if you are conceiving of a ‘recipe’ as a fixed procedure you can use to get a specific result, when things go wrong you will be mystified.
So then you might hop over to a popular bread baking forum and post a question asking why, when you followed the recipe to the letter, your bread came out nothing like the one pictured in the recipe. And then you get some bread heretic on the forum responding to your query with a lot of what seems like irrelevant meta content about microbes and environments and developing intuition. What’s he yammering on about when you’re just trying to find out why the recipe didn’t work like it was supposed to?
This is my attempt to answer every form of that question in one go. When you are mystified by the process of baking sourdough bread, I want this post to demystify it for you and it seems to me that the first part of that is to realize that the concept of a fixed procedure that you can use to get a specific result just does not apply to baking sourdough bread. In simpler terms, when it comes to baking sourdough bread, you should ignore the word recipe.
Instead, when you look at a sourdough bread recipe, think of it as a list of ingredients and a set of very loose suggestions for how you can take that list of ingredients and make a nice loaf of bread out of them. And understand that applying those loose suggestions in a consistently successful way requires you to have a certain level of either explicit and fairly complex, or intuitive and relatively simple understanding of the lifecycle of a sourdough culture and how that lifecycle translates into the rise (and also a significant component of the flavor) of a loaf of sourdough-leavened bread.
Simple Sourdough Lifecycle
In simple terms, a sourdough culture (aka “starter”, aka “levain”, aka a bunch of other terms) is a mix of flour and water in which are living a symbiotic population of microbes (primarily for our purposes, certain yeasts and certain bacteria). When you mix starter into your bread dough, you are inoculating your dough with the microbial culture from the starter and over the next several hours, the microbes eat, reproduce, and spread throughout your dough. Some of the yeasts in the starter are eating sugars in the flour and their metabolism releases by-products into the dough. One of those by-products is carbon dioxide (C02) gas. When they release that gas into your elastic, extensible (thanks, gluten!) dough, it creates bubbles that physically expand the size of the dough. And if the dough is contained by a mixing bowl (or even its own surface tension), its expansion in size is visible as the rise of its level in the bowl. Rising, leavening, is really that simple; your dough rises because the yeasts introduced into it by the incorporation of starter are eating sugars in the flour and releasing C02 bubbles into it.
Sourdough Leavened Baguette
But here’s something that you need to know about the leavening process if you want to make good bread: there is a finite amount of yeast food in your dough and when the yeasts run out of food they stop producing C02 and then the rising / leavening process peaks and comes to an end. After that peak, C02 will “leak” out of the bubbles in your dough and not being replaced by newly produced C02, your dough will slowly start to fall back down. If you let it go to that peak before baking, that’s called “over-proofing” and it’s probably the single most common error that new sourdough bakers make. Ideally, well before the dough falls down, you’ll have baked it which effectively “fixes” the shape of the bread while the yeast is still producing lots of C02 and the dough still has plenty of it trapped inside bubbles, and then you get the nice, light, airy texture that you are aiming for.
So this means that there is some timing involved in when you do what you do in the bread making process and because the sourdough culture is a mix of living organisms that are affected by all kinds of environmental conditions and not a predictable machine, you absolutely cannot pre-determine what that timing is going to be for any given loaf of bread. And that means that if you want to have consistently good results in sourdough bread baking, you have to throw away the idea that you can follow a recipe that tells you to proof your dough for 8 hours or 12 hours (or however many hours…) and instead pay attention to what the dough is telling you about where it’s at in the process. Essentially, you want to make sure that you are putting the dough into the oven within a range of time where the microbes have thoroughly spread through the dough and are actively blowing C02 bubbles and raising / leavening it, but before they have eaten all the food in there and the dough has started to fall back down.
Developing an intuitive understanding of where your dough is at in that cycle, what I call listening to the dough, is the first and probably the most significant milestone in becoming a competent sourdough bread baker. That intuition is the difference between a beginner and an intermediate. And in my opinion, until you have developed that intuition by baking as many loaves as it takes you, in your kitchen, with your starter, and your oven and tools, using the most basic ingredients and procedures, anything else you might be trying to add to improve your results like advanced gluten development techniques, advanced shaping techniques, special ingredients other than flour, water and salt, fancy equipment, highly technical recipes, etc. are all a waste of time and will most likely retard your progress as a sourdough bread baker. Listen: take a basic recipe like this one, and just do it over and over until you are consistently producing far better loaves of bread with it than you can find in your grocery store. Then start trying more advanced recipes and techniques after that.
Temperature Matters Most
A sourdough starter culture is a complex system where large populations of living creatures are being affected by many different aspects of their environment, including each other and what their metabolism collectively produces which itself changes their environment profoundly. For example, one of the significant bacteria in a sourdough culture is one that produces lactic acid as a by-product of its metabolism. That lactic acid does many things. Among them, it changes the pH of the dough significantly, which then plays a large role in determining which other microbes can live and thrive in the sourdough culture. More significantly at our own level of concern, lactic acid is sour; specifically, it is a large part of the sour in sourdough.
But of all the various environmental factors that affect the whole complex process of fermentation in sourdough, the most significant for us, as bakers, to understand and be aware of is the ambient temperature. In simple terms it works like this: all other things equal, the warmer the temperature, the more active the microbial culture is. That means that the yeasts and bacteria eat faster, reproduce faster, raise the dough faster, and use up the sugars they need to eat in the flour faster. Conversely, the cooler the temperature, the slower all that stuff happens.
There are two important take-aways from the effect of temperature on fermentation:
Your Starter Doesn’t Matter That Much
Maybe one of the more “heretical” of my beliefs is that, aside from being kind of miraculous in what it does for us, sourdough starter is really no big deal and other than making your dough rise, it (the starter itself) doesn’t really do much else. In particular, I notice that people imbue their sourdough starter with all kinds of qualities and characteristics, some essential “personality”, that they imagine is being somehow “transmitted” into their bread. And there is this whole niche industry that has arisen around trying to differentiate one starter from another as though using this one instead of that one is going to make a huge difference in your resulting bread. Sorry to all those people who enjoy or profit from all this mythology, but with a specific exception dealing with the amount of starter you use (covered in the next section), I have to say that I have found all of this not to be true at all.
In particular, the idea that one starter or another is going to impart a particular flavor profile to the resulting bread – usually either more or less sour – is extremely pervasive and in my experience, somewhere between largely and completely false. I think that the part of the overall flavor profile of a given loaf of bread that comes from the sourdough fermentation process has far more to do with how the microbes from the starter are affected by the particular flour you are using for your bread, the temperature, the length of the fermentation period, and the ambient mix of yeasts and bacteria that is present in the flour you use, the water you use, and even in the air in your kitchen. A sourdough starter has hundreds of millions to billions of the microbes that are useful to us bread bakers per gram. Individually, they are reproducing and dying at an enormous rate and they are also constantly competing (for food) with each other and with all the other microbes that are introduced into your starter from many sources, most notably the flour they are fed, the water you mix in, and even the microbes floating around in the air in your kitchen. Over time new microbial sub-populations become part of your starter one way or another, so the “character” of your starter is constantly changing to some degree, no matter whose grandmother the starter originally came from.
I maintain my starter in a small jar in my refrigerator. I periodically (and by that I mean very irregularly) refresh it by discarding about 90% of it and mixing in some fresh organic white bread flour (I get mine here, from Breadtopia) and an approximately equal amount by weight of spring water. Although that starter is called “sourdough” starter, when I stick my nose into the jar, it smells quite sweet and mild to me. A lot of people would want to call that the “character” of my starter and suggest that it probably wouldn’t make very sour bread. But my experience is totally different; as far as I can tell, rather than that being the quality of my starter, that is the quality of a sourdough starter that is fed exclusively white bread flour and kept in the refrigerator. And if I take a small amount (1/2 a teaspoon) of my sweet, white flour starter and mix it up with a half a cup of whole rye flour and some water to make a new batch of starter, I find that within a few hours, my new rye starter has developed an entirely different smell and flavor that is much more sour. Rye is the most sour (of the flours I use), but I find that any whole grain flour begets a more sour smelling starter than white flour.
And contrary to what people might think if they smelled my starter, I do like sour sourdough bread and if I make a loaf of 100% whole grain bread and do a long, slow fermentation, the resulting bread will have a very satisfying sour tang to it. Contrariwise, if I want a bread that is not sour, I will use a flour mix that includes less germ and bran (by mixing in some white flour, or sifting out some of the bran and germ) and shorten the fermentation period and then the resulting bread will have little or no discernible sourness at all.
The flavor profile of the starter has much more to do with what you feed it than some inherent character that it has and can impart to your bread. And what are you doing when you mix your relatively small amount of starter into a big bowl of flour and water to make a bread dough? You are creating a new, very large batch of sourdough culture (aka “starter”) where the primary microbe food is whatever flour you are using for your bread. And how the microbes in your starter respond to the particular flour you are using and how long your fermentation period is – again in my experience – are going to have a far, far greater effect on the flavor of the resulting bread than any characteristics of the starter itself.
Except…
The Amount of Starter Does Matter
Here’s the exception to the starter not mattering much in the flavor profile of your bread. While a sourdough culture is fermenting (whether that culture is called a “starter” or “bread dough” in its proofing process), the by-products of the microbial metabolism are changing the flavor of the dough. One of the really obvious changes is that as the lactic acid bacteria produce more and more lactic acid, the dough gets more and more sour. So (all other things equal), the longer you let your dough ferment, the more sour it will get over time. There are other by-products of fermentation besides lactic acid and many of them have strong or subtle effects on the overall flavor profile of the dough.
A mature starter is a hunk of dough that has usually been fermenting for a relatively long time, so it usually has a fairly strong flavor of its own – much more so than a freshly inoculated bread dough. So, in recipes where you are using a relatively large percentage of starter (either by weight or by volume) in comparison to the amount of flour in the recipe, that large-ish amount of starter will definitely have a significant effect on the overall flavor profile of the bread.
Depending on what it is fed and how long since it has been fed, old-ish starter can have a pretty “ripe” quality to it with sharp flavors that many people would find not especially pleasant. So I would suggest that the greater the percentage of starter relative to the amount of flour in a recipe you are using, the more you’d want that starter to be relatively “young” (freshly fed, not having peaked yet).
The other major effect of how much starter you use in a given recipe is how fast the overall proofing process is going to be. Just like a warmer temperature speeds up the fermentation process, introducing a larger population of microbes into the bread dough speeds up the overall process of microbial spreading through the dough as well. So another way to speed things up or slow things down is by using more or less starter relative to flour in your recipe.
That’s really how much I use.
Personally, I like using a tiny amount of starter in most of the bread that I bake. I think that a long, slow fermentation allows the development of interesting and delicious flavors in bread. I think of it in the same way as how slow-cooking a stew brings the flavors together, or aging a cheese gives it the particular quality that it has. That is, in fact, the main reason that I choose to bake with sourdough leavening rather than using commercial yeast which is much faster and more convenient. There are also some reports here and there that a long, slow fermentation catalyzes enzymatic changes in the grain that make the nutritional value of the bread more accessible and the bread itself more easily digestible.
To slow things down, I use about 1/2 a teaspoon (I never measure it) of unfed, cold (straight from the refrigerator) starter in the loaves I make and I let them bulk ferment at room temperature until they have expanded / risen to somewhere around twice (or maybe a little less) the original size of the dough before I shape it and put it in a proofing basket. What I do next depends on my schedule, but usually after shaping I will let the dough proof a short time (30 minutes or so – as always, I am listening to what the dough is telling me) at room temperature and then I will put it into the refrigerator for 12 – 24 hours before I bake it.
Please don’t read this as me saying, “you should use a small amount of starter,” or “using less starter is better,” or anything like that. There are times and recipes where you should use a lot of starter and times when you should use a tiny amount and still other times when some amount between a lot and a little is the right amount. I’m saying that the amount matters and trying to explain why so you’ll have the tools to gauge what makes sense at any given time, and also saying that I usually favor long, slow fermentation periods so I usually use very small amounts of starter.
Dough Hydration
After confusion over length of proofing / fermentation time, probably the next most common mystification in sourdough bread baking (or maybe any form of bread baking; I’m not really sure because I’m pretty much just a sourdough guy myself) has to do with the dough hydration; how wet it is. Technically, in bread baking, hydration is the percentage by weight (or, if you must and in my opinion, you mustn’t, by volume) of water to flour in your dough. For example, if you have 1,000 grams of flour and 900 grams of water, that is 90% hydration. 1,000g of flour and 650g of water would be 65% hydration.
Dough hydration is another area where you are likely to experience problems sometimes if you try to follow a recipe to the letter. This is because different flours have wildly different responses to water. You could measure out the same weight of two different flours and mix them with the same weight of water and have two doughs that feel completely different; one might be relatively stiff, dry, and very manageable and the other might be wet, sticky, and hard to handle.
And when I say “two different flours,” I mean any two different sources of flour, which could include even two different batches of flour of nominally the same grain, milled in the same way (though those will tend to be more similar than flour from two different grains, or floured milled in different ways). White (roller milled) flour has very, very different properties when mixed with water than 100% whole grain flour. Bolted (sifted) flour is different from either white or whole grain. In general, all other things equal, the closer the flour is to whole grain, the more water you will likely need to use to get the same dough consistency. In other words, a 70% hydration dough made with white bread flour might feel similar to an 85% or 90% hydration dough made with 100% whole grain flour.
As with proofing time, in my experience, you also have to hold any recipe instructions that specify a certain amount of water very loosely, develop a sense of the useable range of dough wetness, again, listen to the dough and expect to adjust the ratio of water and flour in a recipe (maybe fairly dramatically) in order to get the dough into that range.
Tips and Tricks
Keeping Starter in the Refrigerator
Almost nothing connected with sourdough baking that I read on the Internet seems more odd to me than the variety and complexity of people’s various sourdough starter management rituals. What that corpus collectively reveals about what people think sourdough starter is and what it’s doing in that jar is mind blowing to me.
Anyway, as mentioned above, I keep my starter in a small jar in my refrigerator. The jar is one of these kind of things with the rubber seal removed so it is well-covered but not air-tight (our favored beasties in our sourdough starter culture are ok with oxygen and since they are producing C02 gas, a sealed container might get blown like my mind).
Every two or three weeks, whenever I think about it, and on nothing remotely like a regular schedule, I spoon out about 90% of what’s in the jar into the little food scraps bucket that gets fed to our wondrous hens (who then miraculously turn that stuff into beautiful eggs and excellent compost ingredients), and then stir about 1/2 a cup of organic white bread flour and an approximately equal amount by weight of spring water into whatever is left in the jar and then leave it out on the counter for an hour or two and then pop it back into the refrigerator.
Watch this:
That’s it – my entire vaunted sourdough management regime takes me maybe 2 minutes every 2 – 3 weeks whenever I remember to do it. No schedules, no real measuring, no worries, and no mystery. I think I must be doing something very wrong, perhaps even approaching sinful, but my starter seems to keep raising the bread up just fine, year after year.
100% Whole Grain Sourdough Leavened Bread
Handling Wet / Sticky Dough
As a beginning bread baker, handling wet, sticky dough was far and away the most baffling and frustrating part of the process for me. I must have watched about 17 bazillion YouTube videos of people deftly corralling their 90% hydration doughs into nice little packages of proto-bread without ever seeming to have any trouble with what inevitably happened to me every time I touched the dough. Which is that I ended up with more dough stuck to my hands and fingers than was left in the mixing bowl and invariably made a giant mess sticking to everything everywhere. I was so intimidated by handling the dough that I nearly decided that the whole project was just too much trouble. Then one day I noticed that on one of the shaping videos I was watching, the person dipped their hand into a bowl of water before they touched their dough. Holy cow; what a revelation.
Wet your hands and then grab the dough. If it starts to stick, wet them again.
You can instead go in the exact opposite direction (the pizza maker route) and sprinkle dry flour all over the dough, your hands, and your countertop. You may find that you need quite a bit of flour everywhere if you are working with a very wet (no-knead recipes) or sticky (rye flour) dough. This works fine and it’s what I did until I finally recently realized that I can just lightly moisten everything with water and I never need to make a mess with dry flour dust floating all over everywhere. Now I wet my hands and the counter before I turn the dough out and I use no flour in the shaping process at all. The only place I use it is a little bit sprinkled into the proofing basket to keep the dough from sticking to the liner.
Transferring Dough from Proofing Basket to a Hot Baking Vessel
The conundrum of how to get your dough from the proofing basket into a pre-heated clay or iron baking vessel seems to be an especially vexing dilemma for a lot of home bread bakers. A lot of people recommend inverting the proofing basket onto a piece of parchment paper on your counter and then you can easily lift the dough into the vessel with the paper’s edges while keeping your fingers far away from the sides of the hot baking vessel.
I’ve done this and it works great. But somehow that paper seemed like a waste to me. So I got a pair of these cheap, kevlar oven gloves that let you just directly invert the dough into the pre-heated baking vessel without worrying about burning your hands. Simple. Efficient. They also work great for later on in the process when you want to remove the baking vessel cover and then remove the bread from the oven altogether.
Watch this (the oven and baking cloche are pre-heated to 450F):
Demystifying Sourdough Bread Baking