Five Things You Thought You Knew About Sourdough

I’m prepared to catch a lot of flak with this post, because I’m going to challenge some of the most cherished and prevalent beliefs about my favorite type of bread and that mysterious microbial ecosystem that makes it possible: sourdough.

I’m not saying these Sourdough Stories are False with a capital F or Myths with a capital M, nor am I proclaiming myself the grand arbiter of high sourdough truth. But there are credible sources that refute or question a good amount of the prevailing lore. If you don’t want to give these Sourdough Stories up, that’s fine. But if it would make your life easier or more interesting to let a few of them go, then feel free to do that, and know that you’re in good, if perhaps not abundant, company.

Sourdough Story #1: San Francisco sourdough bread can only be made in San Francisco. OK, I suppose you could say this one is actually true by definition. But the lactic-acid-producing bacterium (Lactobacillus sanfranciscensis) that supposedly makes SF sourdough unique is found in sourdough starters all over the world, and is in fact the predominant bacterial species in many of those starters. So if you’re not lucky enough to live in San Francisco, or to have a “geniune” SF sourdough starter, don’t despair; a fine sourdough is still attainable. Conversely, some sourdough breads made in SF are positively mediocre. A good sourdough bread has as much, if not more, to do with the skill of the baker than with the specific organism species in the starter. Read this Discover Magazine article to see why sourdough researcher Frank Sugihara said, “I think you can make San Francisco sourdough pretty much anywhere.”

Sourdough Story #2: Starting a sourdough starter involves “capturing” wild yeast from the air. Yeast grow on grain and arrive with the flour. One gram of flour contains about 13,000 yeast cells. I don’t deny that there are a few yeast in the environment that find their way into the starter, but by and large the yeast that will survive in the starter are the ones that like the menu there, i.e, the ones that have a taste for grain. Sure enough, they’re the ones that were on that grain in the first place. And bacteria, the other vital sourdough culture component, are everywhere; you couldn’t keep them out even if you wanted to. Alton Brown’s sock puppets may be cute, but their sourdough-diving antics are largely mere theatrics (which I find is so often the case with sock puppets). When starting a starter, you don’t need to keep your flour/water mixture uncovered by an open window to lure yeast and bacteria. The microorganisms are already where you want them, and leaving the lid off will only attract insects and other riff-raff.

Sourdough Story # 3: The best sourdough starters are made with grapes or other fruits. Yes, yeast lives on fruit. But once again, it’s the yeast that prefer grain that will thrive in the starter, not those that like fruit. And the flour provides ample nutrition for the yeast; the sugar in the fruit is not necessary. Starting a starter requires nothing more than flour and water. Adding fruit probably won’t hurt (unless it’s covered with pesticides), but it won’t help either. (An exception may be Peter Reinhart’s recommendation to use pineapple juice in the initial stages of a starter to prevent a certain type of undesirable bacteria from proliferating; however, I have found that these bacteria die out eventually anyway and the starter is ultimately none the worse for the omission of the juice. In fact, the one time I tried making a starter with pineapple juice, it didn’t work, but that’s probably just me.)

Sourdough Story # 4: Sourdough starter and commercial yeast should never be used together. I’m ducking now, because so many people get their knickers in a twist over this one. It is true that a healthy starter is capable of raising bread all by itself without any help from commercial yeast. It’s also true that some people prefer, for various reasons, to avoid commercial yeast in every situation, and I respect that. Many of the breads I bake are leavened only with sourdough. But the late Professor Raymond Calvel, who is widely acknowledged as the leading all-time expert on French bread, said that a very small amount of yeast (up to 0.2%) might be used in a proper sourdough bread (pain au levain) to increase consistency of timing without affecting the taste of the bread. He also said that using a somewhat larger amount of yeast was acceptable to produce a less sour, more grain-y flavor while retaining some of the flavor complexity and keeping qualities contributed by the sourdough, although the resulting bread could not technically be called pain au levain.

Sourdough Story # 5: A years-old sourdough starter is better than a weeks-old one. A starter reaches its full potency when it is a couple of weeks old, but beyond that, older is not better. My instructor at SFBI told us that many German bakers (the great original sourdough masters) make new starters from scratch every six months or so to keep them fresh. Now if you’re working with your great-grandmother’s starter or one that has traveled the Oregon Trail, and if it’s making great bread for you, I suggest sticking with it. But if you don’t have an heirloom starter, or if you accidentally kill your starter, you probably won’t need psychotherapy. Just grow or beg a new one, and get on with life.

CommentsLeave a comment

  1. says

    I just touched on how I made a sourdough with potatoes recently at work.Story #4 I hasten to add is still being fought over by some purists, but I have to agree with them that adding yeast to the sourdough should then make the baker call it hybrid dough, yeast is an foreign matter when it is used as an add in, especially when your using it and calling the bread 100% sourdough. It’s a topic my friends over at are discussing quite a lot, with the help and guidance of John Downes amongst us home bakers.

  2. says

    Cora, despite Alton Brown’s cheese factor I like him, I just think he missed the mark a bit with his wild yeast episode. Those who know more about cooking than me tell me most of his information is spot-on.

    Jeremy, the question as I see it is not whether you can technically call a bread that contain baker’s yeast “sourdough,” but whether a bread that contains both yeast and sourdough culture can ever be a worthy bread. In addition to Calvel, Hamelman, Reinhart, Lepard, Silverton, Leader, and others have included such recipes in their books. If you get a result you want using both, why not do it?

  3. Anita says

    Excellent post!! I really enjoyed reading about these myths – very educational. One of these days (sooner than later) I’ll make my first sourdough starter.
    Thank you!

  4. says

    Ah, I love to see Myths shattered! That’s particularly interesting that many German bakers make new starters every so often to keep them fresh.

    I also like to hear that Calvel allows for the use of a small amount of commercial yeast. However, being a purist, I don’t think that the resulting bread, even if it uses a tiny amount of commercial yeast, can really be called wild yeast bread – tamed wild yeast bread maybe – or domesticated wild yeast bread. Let me hasten to add that that doesn’t mean I think that bread would be incorrect! It’s just a semantic thing.

    Hearing about Calvel’s idea to add commercial yeast to sweeten wild yeast bread is very interesting. Because I’m STILL fighting with my starter to try to make less sour bread. In fact, I may pack it in altogether and use commercial yeast only from now on. I’m not sure I can take the disgruntled “does it have to be this sour?” comments from other parts of the household.

    • kody says

      I’ve read that for a less sour taste use more of the starter next time to get a faster rise and leave a less sour taste and use less starter for a more sour taste

  5. says

    I guess maybe I’m too easy. It seems to me, if it works for you then it’s a success and call it what you like. Hard and fast rules seem only to make bloody heads and aren’t worth the bother.
    I’m happy with what works for anybody and it’s ok if something else works for you and me.
    So let’s hang out all the myths!!

  6. says

    I must say that after my reading I was under the impression that SF sourdough was indeed SF sourdough and could not be duplicated in other places. This made me seriously bum and give up on sourdough starter. Having said that I am happy to see your post. It gives me renewed interest in making a starter. Thanks for your article.

  7. says

    Thanks, Anita! Good luck with your starter.

    Elizabeth, if you call yourself a purist them I guess I am… an adulteress? But actually, I consider myself a purist too — purely in favor of purely good bread ;-) It should be possible to make bread leavened only with sourdough that does not tatse like battery acid. Opinions vary on how to make sourdough less or more sour. TFL has lots of banter about this.

    Tanna, aMEN to that!

    Lori, you’re welcome. Good luck with your starter too.

  8. says

    I use wild yeasts as well, though I don’t make bread with it often enough to master it. But I have documented how to start and keep a sourdough culture and it sounds like we are on the same page: no potato water or aliens from an open window, just organic rye flour, water, and time.

    I worked as a journeyman baker in my yout’ and I can remember mixing the sour by hand (in a 50 gallon drum!). At the time, the formula book didn’t allow for growing your own: I can recall it saying that a starter was best obtained “from a Jewish shop.” At the time I thought it was some kind of folk wisdom or respect.

    Good to see lots of people are working with natural yeast, any way they can.

  9. says

    Thanks Susan for a great article. I’m a new baker. I have a question: which type of flour do you use to feed your starter that will yield the tastiest bread? Or does it matter? I feed my starter with organic rye flour and the result has been great. But I wonder if there’re other types of flour I should try. Thanks Susan!

  10. Brian says

    Excellent article. I’ve been reading a lot about sour dough, and this really filled in some blanks and dispelled some myths.

    I grew up with what you called an heirloom starter. It was literally over 100 years old and had a great family story to go with it. Now that I’m 35, many of the people who had it are either gone or let their starter die. I was forced to make my own using a little pineapple juice and bread flour.

    It took a while, but almost 2 weeks into it, my starter smells very sour and beer like and is about doubling in a few hours after feeding. I’m going to give it a whirl this week, and I’m very excited.

    Thanks again for this great information.

  11. Glen says

    I agree, excellent article. It seems to me that if you are constantly removing a percentage of starter and replenishing with flour that contains thousands of yeast cells, it is constantly being refreshed. The only way to keep an original strain would be to feed with flour that has been sterilized and keep it in a sterile environment.

  12. Der Bik says

    To: Susan and Whomever Else It May Concern
    Re: A Mystery Sourdough Shout-Out from the Tropics

    I live in an isolated, largely forgotten and therefore necessarily very provincial, corner of the Central American tropics.

    We do not have what Americans might call “ethnic” food or “health food” stores here. We only rarely get a generic brand of tofu in one or two of our “upscale” supermarkets.

    And so I was recently trying my hand at making seitan, or wheat gluten, the plausible meat-substitute used in many Asian vegetarian cuisines. I used a national brand of all-purpose flour (the only kind available) and kneaded it with commercial potable water (one doesn’t cook with or drink the local tap water, or even use it for brushing one’s teeth).

    But I quickly tired of the kneading, and of the various changes of (expensive commercial potable) water. I had a squishy mass of what appeared to be gluten. I didn’t want to fuss with it anymore. I covered it with potable water and left it in its clear plastic bucket atop the refrigerator. I figured I might be able to figure out something to do with it later.

    The next morning I thought, “Hey, maybe this can turn into bread dough.” So, I poured off the murky water, added some commercial yeast mixed with warm water and a little raw cane-sugar to the mess, along with another cup of all-purpose flour. I put it atop the fridge again and waited to see what would happen.

    Today I took a peek and the mess was all bubbly. I tasted it…and it tasted *exactly* like sourdough starter.

    I mixed some more all-purpose flour into it and kneaded until it was rather firm enough to hold some shape, and baked it in a cast-iron dutch oven in an oven set at the highest heat.

    Lo and behold, I turned out to have baked a loaf of amazingly tasty artisanal sourdough bread with a pleasantly sour bite and nice “real bread” bubbly web.

    How on earth did this happen?

    I don’t know that I might replicate the recipe again.

    Did the seitan-making process — the separating starch from protein — do some chemical magic? What role might it have played?

    Mysteries abound.

    More myths await being busted!

  13. Maryann says

    Thanks for the great article. I made a starter for the first time and it was spot on. Absoulely awesome tasting bread. I have to admit I did credit living off the bay of San Francisco to the great flavor. I haven’t made bread anywhere else, but I’m sticking with that myth. What I really wanted to know, because it’s really work to keep a starter alive, was why a 200 year old starter was better than a couple week old one. I started just making a new one every so often and your article justified my action. Thanks for the help.

  14. Ruth says

    Thanks for this! To think I wandered around my property ‘gathering’ wild yeasts as I madly stirred the flour and water for nothing – well not nothing I did get a kick out of it and I’m sure it helped my eccentricity reputation.

    On a sidenote I’d never even heard of San Francisco sourdough bread until now – but I don’t live in the USA.

  15. alex says

    Hi… I’m looking for references regarding the science saying the yeast is in the flour and not the air. I have someone else making the claim that capturing wild yeast is a myth… If they are right I owe an apology… So far an extensive search has only yielded your article. Thank you for clarification via citation.

  16. Pauline Mitsuk says

    I have perused a lot of sites reading about sourdough. I absolutely loved what you had to say. Thank you so much.


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>