Converting Commercial Yeast Recipes to Sourdough

Laurie Ashton is a Twitter friend who caught my attention with her recipe for sourdough challah. When Aleeza asked how to convert regular yeast recipes to sourdough I thought of Laurie, and sure enough, she came through with a clear and thorough explanation. Her guest post is below.

Convert Standard Yeast Recipes to Sourdough

Guest post by Laurie Ashton

I’m not a long-time sourdough baker – I’ve only been baking sourdough (wild yeast) bread for the last couple of years. Since I don’t digest commercial-yeasted bread well, I use sourdough exclusively, which also means trial and error in converting recipes to sourdough.

butt ugly sweet bread, Sri LankaOne of my first breads was a sweet bread that I regularly made for breakfast. Problem was, while it tasted great, it didn’t consistently rise, even after 12 hours. Plus, even on occasions when it rose, it looked butt ugly. What was going wrong?

Turns out I was using too much sourdough starter in my bread recipe. After much research, I learned that a good amount of sourdough starter is about 10 to 20% of the flour weight in fermented flour.

Since I know that’s going to be confusing, let me use an example with easy math. I like easy math. 🙂

Let’s say you use this recipe to make bread:

  • 1000 grams flour (about 10 cups, depending on how you measure flour)
  • 650 grams water (2 3/4 cups)
  • 20 grams salt (4 teaspoons)
  • 2 packages dry yeast

And let’s say your sourdough starter is 100% hydration (that is, a 1:1 ratio of flour to water by weight), then, with a 20% fermented flour target in mind, I would use this:

  • 800 grams flour (1000-200, since I want 20% or 200 grams of the flour to be fermented in the sourdough starter)
  • 450 grams water (650-200 because the starter is equal amounts of water and flour)
  • 400 grams sourdough starter (200 grams flour + 200 grams water)
  • 20 grams salt

You can use less sourdough starter than 10% fermented flour for sure. It’ll take longer to rise, which is a benefit to some people, like if you want the bread to be more sour. But in most cases, I wouldn’t use more than 20%. I say most because I do have a recipe or two where I do exceed the 20% by quite a bit, but those are the exception, not the rule.

What happened to my butt ugly sweet bread when I reduced the fermented flour amount from about 26% fermented flour down to around 12% fermented flour? Ugly old lady butt dimples disappeared, and instead, I had smooth, lovely bread. And it rose! Consistently! Every single time!

butt ugly sweet bread, Sri Lankabutt ugly sweet bread, Sri LankaAnd my husband sang to me, “Baby butt, baby butt, baby butt buns, oh gimme my baby butt, baby butt, baby butt buns…” But he’s a little crazy. 😀

I’m sure the question “Why 20%?” must be occurring to someone. I asked it, too.

If you use too much sourdough starter in the bread, then there isn’t enough food from the fresh flour for the wild yeast to feed on. With insufficient food to feed on, the bread doesn’t rise since live yeast produces carbon dioxide as a byproduct, and what’s what gives bread its air holes.

As well, fermented flour has gluten that’s been overdeveloped (gluten develops naturally when flour becomes wet), which isn’t a problem when the fermented flour is used at low amounts, but when a lot of fermented flour is used, it can’t support the dough properly, hence the ugly dimples and inability to rise.

Laurie is a Canadian transplanted to Sri Lanka. Read more at my food blog Chilli & Chocolate, my blog on life in Sri Lanka at A Canadian in King Parakramabahu’s Courtl, and my writing blog Peregrinas. Or Follow me on Twitter.

Related: Make Your Own Sourdough Starter at Home


  1. Good insight on the danger of too much starter and how it works.

  2. Right to point without a lot of technical theories of how much starter I need when converting recipe to sourdough.

    I spent hours on the net looking for an answer to this question. You can’t believe all the technical info…on the subject.

    I was ready to give up. Then I said someone out there must have a simple answer for my question. Thank goodness for your site.

    I’ve only been baking sourdough breads for about 2 years, just like you. Now I know how to convert my recipes without all the technical terms that some associate sourdough baking with.

    I can’t get over how many mathematical geeks love Artisan baking. When they try to help you out they talk in numbers. I get lost.

    I do use a digital scale for measuring my ingredients but that’s it.

    I’m baking up a beautiful loaves of Artisan breads without all the technical jargon. I have a natural feel for dough that’s a big help too.

    Just wanted to thank you for the info…


  3. Laurie Ashton Farook says

    Mimi, glad to hear you found it insightful. 🙂

    FH, happy to help and I’m glad to hear you didn’t find it too complicated or too math-geeky. I *am* a math geek, but tried to use easy-to-understand examples, and no, I have no idea why so many math geeks get hooked on sourdough. Seems a bit of an odd association, doesn’t it? 🙂

  4. This is great info Laurie! Thanks for sharing!

  5. Lisa Caponigri says

    I’m a novice at this, and I’ve run into the problem of the yeast not rising, too. I’ll definitely work your tips into my next batch!

  6. Lol, the bread is cute…it does look a little like a cute pair of butt 🙂 it’s great that you chose to share this idea with us, though I usually try to implement yeast free food at home, especially if they involve commercial yeast. Still, I would love to try this and see how it goes for me.


  1. […] You can also take a look at the methods offered here, here, and […]

  2. […] post originally appeared on the Cooking Manager blog as a guest post back in early February of this year, Cooking Manager is run by Hannah Katsman whom I first met over […]