Baguettes – Take a walk on the wild (yeast) side.

What makes sourdough bread rise?

Why, yeast – of course.

But how does sourdough bread rise even when there’s no yeast in the recipe?

Wild yeast – the stuff that’s floating in the air all around us.

After all, our frontier-settling ancestors weren’t packing Fleischmann’s RapidRise in their Conestogas.

They had to rely on their own homemade “brew” of fermenting flour and water, and the wild yeast it attracted: sourdough.

If you’re a bread baker, you’re familiar with all kinds of yeast. Your mom probably learned to bake bread with compressed yeast, a crumbly, moist yeast that comes wrapped in individual squares. Due to its perishable nature, compressed yeast has pretty much fallen out of favor with home bakers.

You yourself probably grew up with the aforementioned Fleischmann’s – either RapidRise, or their classic active dry, in the bright yellow packet (or brown glass jar).

Or perhaps you learned to bake with Red Star, another active dry yeast that’s been around for decades – since 1887, to be exact.

Nowadays, instant yeast is all the rage. So within the space of about two generations, we’ve moved from compressed yeast, to active dry, to instant – a category that includes bread machine yeast, and “rapid” yeast.

So, what’s the difference? Say, between between active dry and instant yeast? Or among RapidRise, instant, and bread machine yeasts?

Well, they all start with Saccharomyces cerevisiae, just one strain of the more than 1,500 identified species of yeast.

1,500 strains of yeast? But wait, there’s more – literally. Those 1,500 identified yeasts are just an estimated 1% of the yeast population in the world; most species remain as yet unnamed.

And what exactly is yeast? It’s a single-cell organism, part of the fungi kingdom. The yeast we use most often today, Saccharomyces cerevisiae, is one of the oldest domesticated organisms known to mankind: it’s been helping humans bake bread and brew alcohol for thousands of years.

Used to be, there was quite a difference between instant yeast and active dry; active dry contained a greater percentage of dead cells, which “cocooned” around the live ones, making it necessary to “proof” the yeast – dissolve it in warm water – before using. This water bath dissolved the dead cells, and freed the live ones for use.

These days, active dry and instant yeasts have just about the same number of live cells. So, active dry yeast no longer needs to be dissolved before use; simply mix it into your bread dough along with the rest of the dry ingredients, just as you do instant.

SAF leads the way among instant yeast brands. Produced by France’s LeSaffre company, largest yeast producer in the world, SAF Red is widely used by professionals everywhere – including the bakers in the King Arthur Bakery and test kitchens.

SAF Gold, another SAF variety, is an “osmotolerant” yeast, perfect for sweet breads, and any dough with a high amount of sugar.

How does it work? Sugar likes to absorb water; and when sugar’s in bread dough, it pulls water away from yeast, leaving the yeast thirsty. The yeast cells in SAF Gold are bred to require less liquid to live and reproduce; so they’re better able to withstand sugar’s greedy ways with water.

Next up:  RapidRise, instant, and  bread machine yeasts. Is there truly any difference?

It’s widely agreed that instant yeast and bread machine yeast are the same beast. But then, the plot thickens…

We’ve spoken at length to representatives from Lallemand (another large yeast company), Fleischmann’s, and SAF/Red Star (both brands now owned by LeSaffre). And there’s no agreement, even among folks from the same company, as to whether RapidRise and instant yeast are the exact same yeast, save for their names (RapidRise is Fleischmann’s trademarked name).

Having beat our collective heads against this brick wall long enough, we decided to… well, remain undecided, for now. Personally, I find RapidRise is faster out of the gate than SAF, but gives out sooner. And since I like to give my loaves leisurely rises (a long rise brings out bread’s flavor), I like SAF.

That’s my yeast story, and I’m sticking with it!

Now, back to our wild yeast, and the bread it produces: sourdough. Saccharomyces exiguus, one of the most common wild yeasts, flourishes in a simple flour/water medium. Put flour and water on the counter, and you’ll probably see your liquid begin to bubble in a few days. That’s wild yeast at work.

Unfortunately, Saccharomyces exiguus alone isn’t the most effective yeast for raising bread dough. Saccharomyces cerevisiae is better at converting flour’s native sugars into an easily digestible yeast food. So, while you can make bread with sourdough alone – no dry yeast – adding a dash of SAF instant or another processed yeast will certainly help things along.

These days, with all kinds of dry yeast widely available, we don’t need to rely on sourdough for its leavening power. Most folks use sourdough for its rich, tangy flavor, rather than its leavening power.

Still, it’s fun to make a loaf of bread using just sourdough every now and then; our Extra-Tangy Sourdough is such a loaf, if you’d like to experiment. It takes about 24 hours to make, start to finish; but it’s well worth it, if you’re a true sourdough aficionado.

The following recipe combines the best of both worlds: sourdough’s flavor, and dry yeast’s leavening power. The resulting loaves are typical crusty baguettes, with a pleasing hint of tang from their sourdough starter. Enjoy!

First, let’s get our sourdough ready.

Uh-oh… looks like it’s been awhile since I’ve fed the poor thing.

No worries. I’ll just pour off most of that dark liquid…

…stir it up…

…and it’s ready for a meal.

Note: If the liquid atop your sourdough is pinkish; or if it smells bad – “off,” rather than fresh, tangy, and alcohol-like – it may have become infected with harmful bacteria. Best to discard it, and build yourself a new starter.

Transfer the starter to a bowl, so you can wash out its container.

If you like, discard 1 cup of starter; this will control the amount of starter you’re dealing with. If your starter is scanty and you’re trying to build up the amount, there’s no need to discard.

Or, if you do discard – yet don’t want to simply “discard” – use that extra cup of starter to make Sourdough Waffles, the best waffles you’ll ever taste.

Add 1 cup flour (King Arthur Unbleached All-Purpose, of course) and 1/2 cup lukewarm water to the remaining starter. Notice this is equal parts flour and water, BY WEIGHT.

Stir to combine.

Cover, and let rest for a minimum of 4 hours, or for as long as 12 hours.

Your goal is an actively bubbling starter, so give it as long as it needs.

Remove 1 cup of starter for your baguette recipe, and put the remainder back in its crock. Store it in the fridge till next time.

At last! Let’s make baguette dough. Put the following in a bowl:

1 cup fed sourdough starter
1 1/2 cups lukewarm water
1 teaspoon instant yeast
1 tablespoon sugar
2 1/2 teaspoons salt
5 cups (21 1/4 ounces) King Arthur Unbleached All-Purpose Flour

Mix to make a rough dough…

Then knead till smooth. You’ll find this dough is particularly silken.

And look at that gluten development!

Allow the dough to rise, in a covered container, for 1 hour.

You should see it gain a bit of volume.

Refrigerate overnight, or for up to about 18 hours.

Whoa! Now THAT’S a nice rise!

And look how beautiful the dough is – still so silky smooth.

Next, divide the dough into six equal pieces; a scale makes the task easy.

Shape each piece into a rough cylinder. Cover the pieces of dough, and let them rest for about 10 minutes. This will relax the gluten, making them easier to shape.

Working with one piece of dough at a time, gently flatten it.

Fold in half lengthwise…

…and seal the seam, using the side of your hand.

Repeat the process, flattening the dough, folding over, and sealing.

You’ll have a loaf that’s already about 10” long. Gently roll it under your cupped fingers to a loaf about 12” long. Put the loaf on a parchment-lined or lightly greased baking sheet.

Repeat with the remaining pieces of dough, using two baking sheets.

So OK, they’re not perfect, looks-wise. But beauty is only crust-deep!

Cover the pan, and let the loaves rise until they’re very puffy, about 3 hours.

Towards the end of the rising time, preheat the oven to 425°F.

The risen loaves should look about like this.

Spray the loaves with lukewarm water…

…and, holding a very sharp chef’s knife or heavy serrated knife at a 45° angle to the dough, make three diagonal slashes.

Be aggressive enough to make a deep cut.

Once you’ve slashed the loaves, don’t fool around. See how they’re deflating? You want to get them into the oven immediately.

After just a minute or so in the oven, you can see them picking right up.

Bake the loaves for 25 to 30 minutes, until they’re a deep golden brown.

Like this. They’ll probably be slightly flat, rather than perfectly cylindrical.

For rounder, more shapely loaves, use a baguette pan.

Nicely risen…

…slashed, and into the oven they go.

30 minute later – fini!

Six lovely baguettes.

Look at the top vs. bottom crust; love that blistering, don’t you?

Here’s the difference in shape between baking baguettes freeform, on a baking sheet (left); and using a baguette pan (right).

Can’t you just hear that crust crackle as you tear into a hot baguette?

Nice crumb, eh?

Read, bake, and review (please) our recipe for Wild Yeast Baguettes.

One final word – our yeast video is a great live-action comparison of the various yeasts discussed here.

PJ Hamel

PJ Hamel grew up in New England, graduated from Brown University, and was a Maine journalist before joining King Arthur Flour in 1990. PJ bakes and writes from her home on Cape Cod, where she enjoys beach-walking, her husband, two dogs, and really good food!


  1. Efrain Vargas-Hernandez

    Hi I just made these today. They turned out great however I had to use my own method of shaping and proofing in a couche to achieve a nice cylinder loaf. I could not find any recipe to print out. I had to use my laptop in the kitchen while I did the baking. Also there is no mention how long to mix the dough other then mix until it is smooth. Where can I find the recipe? Thanks for the tutorial.

    1. The Baker's Hotline

      No worries, Efrain, the recipe is always linked right below the main photo of the blog article if you’re looking for it. Kneading will be around 4 minutes at speed 2 in your mixer, or until the dough is smooth and pillowy. Happy baking! Annabelle@KAF

    1. The Baker's Hotline

      While instant yeast isn’t necessary when baking with sourdough starter, most of our recipes call for the addition of commercial yeast to ensure a high rise and pleasant structure in the finished loaves. You’ll still get the tangy flavor from the starter, but the bit of added yeast will move the process along and ensure fabulous results. Happy baking! Kye@KAF

    1. The Baker's Hotline

      Annie, you’re looking to make bread without any added yeast, try using our Extra-Tangy Sourdough Bread recipe. You can shape the dough into baguette shapes instead of loaf shapes if you like; using this formula and method will give you better results than simply leaving the yeast out of this recipe. Good luck! Kye@KAF

  2. Barbara

    Yikes. This is *not* a recipe to retard the second rise by putting it in the fridge overnight (a practice I follow with my other sourdough breads because it deepens the flavor & brings out complexities). I took shriveled, mummified sticks out of the fridge to bake off for this morning’s breakfast. “Huh… the oven spring must be amazing,” I comforted myself. I gave them a good spritzing and slashing and popped them in the hot oven, hoping that they’d plump up and at least look edible. Eh, not so much. 🙁

    1. The Baker's Hotline

      There a number of different reasons things could have gone wrong here, Barbara, but it sounds to us like your shaped loaves over-proofed during their time in the fridge. If you give our free Baker’s Hotline a call at 855-371-BAKE, we’d be happy to troubleshoot with you for a better next experience. Mollie@KAF

  3. Larry

    I’m a very new baker, so forgive me a beginner question. First, I made my sourdough starter from the KAF recipe, then tried these baguettes using some starter that would have been discard. And … success! Six loaves — 3 from baguette pan very pretty, 3 from baking sheet rather homely, pretty much as you described. And absolutely tasty!

    The only problem I ran into was after the second rise. I gave them all of 3 hours (in oven with light on to compensate for cool house). When it came time to slash the tops, there was a skin on the dough which led to the slashes creating a bit of a mess. Is that normal or did I let them rise too long or should I have covered them while they rose?

    Thanks for a great resource. I took Bread 101 at the KA’s Baking Education Ctr. last fall and it gave me courage to begin this journey!

    1. The Baker's Hotline

      When letting bread rise, please keep it covered so that pesky skin does not form. If you don’t want to have the plastic on the dough, try using a clean bin liner and putting the whole tray in there. Blow some air in it to puff it up and close it tightly, then let the bread rise. Happy baking! Laurie@KAF

  4. MattieMay

    I’ve tried a couple of your recipes, I got my sourdough starter going from scratch over several days, here’s my problem: Every recipe I try is dry, my dough never looks wet or smooth like the pictures. I measure it out exactly, my starter has usually doubled or tripled before getting the cup of it out i need and I use a dough whisk for mixing. I love using 1/2 white 1/2 wheat flour and understand i need more water for the the wheat? Also, my husband picked up the bread flour instead of the all purpose, i believe you use less flour….can you help me? do i just need to add more water or less flour. When i just tried the above recipe same problem and i only used just over 4 cups of flour! What am i doing wrong?

    1. The Baker's Hotline

      If you are replacing white flour with WW or even bread flour expect to add more liquid. If you made this recipe with half WW and half bread flour and did not add any extra liquid the dough was probably dense and heavy. The rise will be less than enthusiastic and will be dry in texture. When trying a new recipe it is best to not make any changes so you have a baseline. Then introduce changes gradually. We have some great blogs on WW baking. Try this one called <a href= White to Wheat Happy baking! Elisabeth@KAF

  5. veracity

    The one thing that is missing from this post, (which is so important) is WHY wild yeast is better than dry or instant. Wild Yeast requires a long rise (12-13 hour MINIMUM), and there’s a reason for that. The long rise is what creates the right environment to break down the phytic acid in the wheat through fermentation. Why is that important? Because without breaking that down, wheat in the “rapid rise” state is actually unhealthy for our bodies (literally cannot be digested properly)…that means pretty much all modern bread. Do people not look at the growing “gluten free” aisles in their grocery stores and honestly not question why this is happening? Modern bread (and let’s put gmo corn, gmo soy, rapeseed, cottonseed and all the other poison oils and other junk added to bread, to the side for a moment) actually steals nutrients from your body, and that is just thanks to the flour and quick rise yeasts alone. My comment would be way too long to post all the science but do an online search, answers are out there.

    The advent of “quick” is killing us, and “quick” has everything to do with making money…in every sense..think about that. Our food is literally killing us and people have to start waking up and realizing this. We trade health because our lives are busy and hectic, “quick” is the bandaid solution (and the big corporations know it!!) But at what point is the trade-off no longer worth it? There is more cancer now then there has EVER been. Why? Reasons are out there we just have to be willing to look for them and then find the solution to fix it…If not for ourselves, for our families and future generations.
    Thanks for sharing your views. We always hope that our customers and fellow bakers will make healthy choices for themselves and their families, and we’re always happy to share any info we have when questions arise. ~ MJ

  6. mstebby

    Instead of making 6 loaves of bread could you use some of this for pizza dough?

    Absolutely – this is a very versatile dough, and it would be fine for pizza crust. Enjoy – PJH

  7. karylhansen

    If I want to halve this recipe, do I just halve all the ingredients? Or is it better to use the full complement of yeast as some recipes recommend?

    Karyl, we were just talking about this yesterday – whether halved bread recipes should have their yeast halved or not. I guess bottom line, it depends how long you’re willing to wait; obviously, if you halve the yeast the rise times will be longer – which isn’t a bad thing, as rising develops flavor. So if you’re in a hurry, don’t halve; if you can wait, do, and note how the rising times change. It might not be as dramatic as you’d think. Hope this helps – PJH


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