Going Wild

One of the questions I get asked most often is how to take a bread recipe and substitute sourdough starter for baker’s yeast.

The short answer, in my humble opinion, is: you can’t. Do I hear gasps? Can Ms. Wild Yeast be advising against using wild yeast?

No, she isn’t. But let’s think about this a minute. You have a recipe you like, and it uses baker’s yeast. (You do like the recipe, don’t you? Otherwise why would you want to keep it around?) Now you want to simply take out the the baker’s yeast and replace it with wild yeast. Simple, right?

But with sourdough starter, you’re not only adding yeast, your’re adding flour, water, bacteria and the acids they produce (these are what make sourdough sour), alcohol, and other compounds that are products of fermentation. And in so doing, you’re potentially going to be changing (for better or worse) some things: dough consistency and strength, fermentation time, keeping quality, and, of course, flavor and texture of the bread, to name a few.

So, what was it you liked about that original recipe, anyway? If you care to, you can read more of my thoughts on tweaking recipes. It pretty much boils down to this: if you do things differently, you may well wind up with a different result.

That said, I don’t want to make it sound like you can’t or shouldn’t use a baker’s yeast recipe as a starting place to develop a different, sourdough-leavened, bread. What I can tell you is where I would start If I were going to do this (and I have, plenty of times). What I can’t give you is a pat formula — and that would be boring anyway, wouldn’t it?

I’m assuming that you use a scale, know the hydration of your starter, and are starting with a recipe that gives ingredients in grams. (If you don’t, I’m very sorry but I’m probably not your best bet.) I’ll also assume your original recipe is a “straight dough;” that is, it does not contain a preferment such as a poolish or sponge; I can talk about those in another post if anyone is interested.

I start by thinking about how much prefermented flour I would like to have in my dough. In other words, how much flour will be contributed by the starter I will add? Typically this is between 15 and 25%, although for rye and whole-grain breads it is often higher. I think a good place to start is 15% (which is, by the way, the percentage of prefermented flour in Norwich Sourdough). If you don’t like the result you can change it on the next batch.

Now look at the original formula. Let’s say it is

  • 500 g flour
  • 325 g water
  • 5 g yeast
  • 10 g salt

15% of the 500 grams of flour is 75 grams. So I need to know how much of my starter contains 75 grams of flour.

I keep a 100%-hydration starter, so the calculation is easy. In a 100%-hydration starter, there are equal amounts of flour and water, by weight. Therefore, to get 75 grams of flour, I need 150 grams of starter, which brings along with it 75 grams of water. If your starter has a different hydration, you will need to do a little more math.

Now, since I’m adding 75 grams each of flour and water, I reduce the flour and water in the final dough by those amounts. This maintains, in the final dough, the same ingredients as in the original recipe, minus the yeast. My adjusted formula becomes

  • 425 g flour
  • 250 g water
  • 150 g 100%-hydration sourdough starter
  • 10 g salt

These numbers are the easy part, and remember they are just a starting point. Some things to keep in mind:

  • In general, sourdough likes a higher dough temperature than baker’s yeast doughs. (Dough temperature is controlled with water temperature.)
  • The dough may actually need less (or maybe more) water than its baker’s yeast counterpart. (I hold back a small amount of water to make adjustments in the mixing process, don’t you?)
  • The dough will almost surely need a longer fermentation time than the original recipe.
  • Sour flavor increases with a larger amount of starter in the formula and with longer fermentation times. But fermentation time decreases as the amount of starter goes up. In my experience, increasing the amount of starter has a greater impact on sourness than increasing fermentation time.
  • A higher dough temperature also decreases fermentation time. Depending on whom you talk to, a higher temperature may increase or decrease the sourness of the bread. Have fun with that.
  • The acidity of sourdough makes the dough stronger, with the effect increasing as fermentation time increases. You may need to mix the dough a little less initially.
  • Think of this as an iterative process to get to the result you want, and do what works for you!

CommentsLeave a comment

  1. says

    Overall, I find using LESS starter gives more of a sour taste. It gives the bacteria longer to work.

    If you use a fresh and healthy starter, which I always recommend, you aren’t adding sour with the starter like you’d add chocolate taste by adding chocolate chips, but the organisms that will create the sour taste.

    If you check out Dr. Wood’s first book, he has a recipe for a San Francisco sourdough bread he makes 4 ways. One has 4 cups of starter and is risen in about an hour (if memory serves), the next has one or two cups of starter and is risen in 4 to 6 hours, the last has 1/4 cup of starter and takes about 16 hours to rise. The hydration of all the doughs is the same.

    The last one, with 1/4 cup of starter, is MUCH more sour than the first two.

    Obviously, your mileage may very,

  2. Mike Maxwell says

    Great post – as usual. I have been experimenting with adding a starter that is at various stages of maturity, and using various techniques to grow the starter (time temperature, hydration, etc.) I have found the condition of my starter (maturity, how it was grown) has more impact on the final loaf then the amount of starter used.

    BTW – I read your link to the old post “On Tweaking”. After thinking about it I realized it was second nature for me to wait until tasting the final product and then decide if I had been cooking in “Mode 1″ or “Mode 2″. Now that I’m aware of this I know my conscience will force me to mentally “declare” mode 1 or mode 2 in advance. Thanks for the nightmares. :~)

  3. says

    Wow. I was under the impression that nearly any bread recipe could be “adapted” for sourdough, and your explanation is wonderfully thorough and makes perfect sense. You are a good teacher for those of us that are still new to sourdough. This post was fun to read.

  4. says

    I thought you lost me for a moment when you started talking calculations, but then I remembered, “Oh, this is Susan, I can ‘zone out’ and she’ll still be able to cast that spell upon me.”


    Seriously, I ALWAYS learn from you. The Norwich is my all-time favorite recipe when i want a consistent loaf of bread.

  5. says

    Susan, this post will definitely become yet another classic in your long collection!

    Excellent explanation, will be helping a ton of folks in their experiments with sourdough

  6. says

    Good to know. Sometimes we tend to think we can make all these substitutions at will – but I learned from an ol’ boyfriend who was an Executive Chef that baking is chemistry. Change one item and everything changes.

    (He wasn’t such a hot boyfriend – but I learned a lot about food and cooking that year. My husband now is the beneficiary of all that learning.)

  7. Stacey says

    I would love to hear what you have to say about substituting wild yeast in commercial-yeast recipes with pre-ferments. So many of my favorite bread recipes use a biga or a poolish and I’m itching to try them out with my starter, so if you have any tips or considerations, I’d love to hear them before I waste a bunch of time and flour!

  8. Jennifred says

    These loaves look like salted baked potatoes! They look luscious and I want to try making them.
    I am so glad I found your site!

  9. SoothingBread says

    I think you must have had a typo estimating salt – by volume, 2g would be 0.4%, leaving the bread fairly flavorless! Perhaps 9g or 10g would be better?

  10. Laura Hinrichs says

    Help: Please say how to start a rye starter. I have both whole wheat and white barm. Where to go from here?


  11. Maria Boyd says

    I am new to this and enjoying making rye sourdough at the moment
    Your blog has answered many questions in my mind, thank you
    I don’t know who you are,what is your name?
    I am facinated by the science of it all which you clearly understand. This knowledge enables one to be flexible and experiment
    Having said that the process is so simple
    Do you have a book on the subject and what is the title
    I look forward to trying out more things


  1. [...] Adding starter to your recipe adds flour and water as well as yeast so the balance in your recipe may have been altered. The above formula gives a starter that is at 100% hydration (equal quantity of flour and liquid by weight) so, if you add 100g of starter, you will have added 50g of water and 50g of flour to the recipe in addition to the yeast. For a thorough rundown on how to convert a recipe, please see the Wild Yeast Blog. [...]

  2. [...] Adding starter to your recipe adds flour and water as well as yeast so the balance in your recipe may have been altered. The above formula gives a starter that is at 100% hydration (equal quantity of flour and liquid by weight) so, if you add 100g of starter, you will have added 50g of water and 50g of flour to the recipe in addition to the yeast. For a thorough rundown on how to convert a recipe, please see the Wild Yeast Blog. [...]

Leave a Comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>