Th Kitchen Yeast Myth

Lots and lots of preferment and starter questions these days as industrious home bakers gear up to make Christmas panettone, stollen and other festive breads. One question keeps recurring and it is: what’s the best way to encourage the unique wild yeasts in my kitchen to grow into a starter? The answer, unfortunately, is that there really is no practical way to culture the wild yeasts that occur in your home.

There’s a pervasive myth out there — and I don’t know where it started or who started it — that homemade starters are local yeast capture devices. Which is to say, that home starters grow because wild yeasts in the kitchen invade the flour slurry and start growing there. In actual fact, home-grow starters grow because the yeast that’s already in the flour when you buy it starts to multiply and thrive.

Wheat berries, you see, get covered with yeasts of different kinds as they grow in the field. The little beasties wait on the berry surfaces in hopes of being first to the starch buffet when the seed germinates and cracks open. If you’ve ever noticed the thin white film of yeast that covers grapes or plums when you buy them, it’s pretty much the same phenomenon. That yeast isn’t — and really can’t be — completely removed when the wheat berries are ground into flour. Which means that every bag of flour arrives at the grocery store with some yeast already in it. It’s this yeast that we cultivate when we make a starter.

Which is not to say that some local microbes won’t invade your starter either at the beginning of the process or over time, however they’ll tend to get out-competed by the more numerous yeasts that are already in the flour. Still if you keep your starter going for months or years you’ll increase the odds that it will start taking on some local character, even though you’ll be constantly re-inoculating it with yeast from Kansas or North Dakota or Idaho whenever you feed it.

Sorry to burst the bubble of any starter romantics out there!

18 thoughts on “Th Kitchen Yeast Myth”

  1. I’ve always had terrible luck with starters. Give me a packet of store bought yeast any day of the week.

    1. I hear you, Darren. The trick is just to feed ’em and not worry much about ’em otherwise. Assuming you want to try again of course. 😉

      – Joe

  2. Out of pure curiosity, if you were somehow able to culture and maintain a truly local yeast starter, would it actually make that big of a difference?

    1. HI Richard!

      That’s a very good question and I think the answer is no. But then yeasts are only half the equation where starters are concerned. I’m going to put up another post on this sometime this morning.

      – Joe

    2. I have read about particular San Francisco sourdough bread which is very special because of one bacteria species which lives only there and gives their starter distinct flavor. Haven’t tried this bread, though, so maybe it’s just good advertising 🙂

  3. I have heard that home beer brewers place containers of starter in the orchards when they are blooming, to catch wild yeasts from pollen. But I don’t know whether this practice is based on some evidence about wild yeasts or also is just myth.

    1. Hi Antuanete!

      That’s interesting and it makes sense since orchards are rife with wild yeast eager to feed on fruit. Neat technique!

      – Joe

    2. Antuanete:

      You’re right, we do sometimes look for wild yeasts, though more often than not, we’ll go to our local homebrew supply store and pick up a particular strain of yeast for the beer we’re working on.

      The practice started in Belgium, where large open vats of unfermented beer, known as wort, would be stored in the attics of the brewhouses, to cool. Later, fans were added to the windows to encourage circulation. Consequently, the wort was inoculated with the local yeasts. These beers, known generally as lambics, are still produced, though many of the breweries maintain a culture of the yeasts involved in order to maintain a more predictable product.

      You see, the problem with open fermentation, and the reason that true lambics have such an interesting flavor profile is that in addition to saccharomyces cerevisiae (the bacteria you use get at the store and one of the ones which we use to brew) you’ll pick up brettanomyces bruxellensis (actually named due to it’s discovery and identification in brussells), which provides a lot of the musty, low notes in Belgian beer, as well as several varieties of lactobacilii, which will sour the beer somewhat.

      Nowadays though, most of the strains which have identified positive effects on beer have been isolated and are actively cultured, so it’s not often that someone will go through the effort of trying to capture local yeasts for cultivation, as it can be a crap-shoot as to what yeasts you pick up, as well as the possibility of a detrimental or unintended infection. Each batch of beer represents a significant investment (in time and money) for the brewer, from the home brewer practicing his (or her) craft in the garage to national chains. Consequently, most brewers prefer to control as many variables as possible.

      If you’d like to see what some of the different yeasts taste like, try some Belgian beers: Chimay is tasty, as are Delirium, and Rodenbach Grand Cru as a sour. Enjoy!

      1. Wow, thank you a lot for such a detailed post. Next time in Brussels, I will definitely try some of mentioned beers, as every time I’m struggling with incredibly large choice of beers in bars 🙂

  4. Not really understanding this, Joe. I mean I get what you’re saying about yeast being resident on the berries/flour and I’ve read about that on a number of occasions so I appreciate that it’s an accepted belief. But, still, authentic San Francisco sourdough is being baked with the same flours from TX, KS, NB, etc. that the rest of us use. And I don’t hear anyone in CO or OK touting their sourdough even tho I’m sure they’re justly proud of their wheat/flours.

    At my house (because I neglected and lost my last sourdough starter several months ago) I’ve been experimenting with a variety of starters lately. I’ve got one that was jump started with commercial yeast, one started without using just flour and water, one bought online from a SanFran culture, a whole wheat one from a SanFran friend who isn’t shy about boosting his with commercial yeast from time to time and one bought online from IA. To try to decide which of these to continue feeding and giving real estate in my fridge, I baked very small loaves (large rolls, really) on the same day from the same ingredients loaded into the oven together.

    There really were differences of flavor, crumb and crust. The whole fan saw and tasted them (wish I’d taken pix). So I hafta believe there’s more going on than the opportunistic yeast hitching a ride in my flour sack.

  5. I tried for months to get a starter going with nothing but the “wild” yeasts in my kitchen and never, ever succeeded. I now have a starter given to me by a friend. I always thought it was just me – glad to know I’m not alone.

    1. I tried and failed at “starting” starters until I relaxed and just combined flour and water…and let it sit. Adding a little rye flour to a beginning starter can be useful since it’s already germinated…and hence loaded with yeasts and bacteria. Give it another whirl! 😉

      – Joe

    2. Were you feeding what you hoped would become a starter for months or did you spend months attempting starter after starter? Did you leave it open to the elements so the beneficials could take up residence? I use canning jars with bail closures. When I’m building the starter I engage the top and bottom halves of the bail but don’t secure them. Did you refrigerate it too soon? It isn’t ready to be arrested by the cold until it’s vigorous.

      This process takes a while you realize. You may not see the first bubbles for days or a week. Then it can take days more to build the colony and the sour character. In the process you can get that liquid hootch layer. That should dismay you. Stir it back in; it’s supposed to have properties that discourage the unproductive or noxious bacteria that may also want to feed on your flour and water medium.

      I wouldn’t give up for at least 2 weeks. By then it should be bubbly and capable of doubling itself overnight when you feed it. And, as Joe says, feeding it with rye flour can really help speed things up. Even if it’s not a rye starter you’re after you can switch the feeding to wheat flour (whole or AP once you’ve got a hearty starter going.

      1. I really can’t type and, Joe, it would be wonderful if there were an edit button.

        About that hootch: it should say if you see it laying on top that SHOULDN’T cause you dismay.

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