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. kmjas1

    Hi, your link to Wild Yeast Baguettes is not working properly.
    Hope you can fix it. Thanks for expanding my knowledge on yeasts.
    I end up with a yeasty taste in my cinnamon rolls using regular yeasts. I proof it and do not use more than the recipe calls for. Would it help the flavor if I changed to SAF Gold? – Mary J

    Mary, changing to SAF Gold won’t add “yeasty” flavor or aroma. If you like the taste/aroma of active dry yeast, then by all means use it for all of your baking; instant yeast isn’t the solution for every bread baker, and there are those who swear by the flavor of active dry… PJH

  2. tomyeap

    The inside of the baguettes are not white. I even tried the bleached and unbleached. Over mix or under mix? Thanks.

    In general, you’ll have creamier color the less you mix; whiter the more you mix. If you want stark white, you’d have to use bleached flour. PJH

  3. empressqueenb

    Is it possible to use whole wheat flour to do the starter & bread? I’m trying to do 100% whole grain as much as possible. Thank you.

    No, not and get the same result. You can certainly use 100% whole wheat flour, but you’ll need to experiment with the amount of water; and you’ll get a much denser, smaller loaf, very close-grained and somewhat moist rather than airy/crunchy. Your best bet would be to find a whole-grain baguette recipe, rather than try to retrofit a classic baguette recipe to use whole grains. We have a whole-wheat baguette recipe in our King Arthur Flour Whole Grain Baking book – give it a look sometime. Good luck – PJH

  4. eclifford

    PJ, I took the sourdough class this summer, having good luck with texture and flavor, but shape continues to be a problem for me. I’m using the recipe you gave us. Need tips for getting the height I want from bowl-risen boules, rather than the spread. I’d like a nice round ball I could use for a bread bowl. I’ve been experimenting with various techniques, but no resolution so far. All my boules are wide and flatish. Flour content? Rising time? Oven temperature (I generally use 485F)? I do add a little instant yeast to the flour when starting out (about 3/4 tsp.). Thanks

    Many times when this flatish spread occurs, it may be because of the rising time. While in its last rise, try to take it a little earlier! PJ? Elisabeth

    Sorry, I’m not familiar with the sourdough class – perhaps contact the folks at the BEC? could give you the contact info. of the person who taught the class. In the meantime, I often have the same issue – flat rather than tall. One solution is to use less liquid; make a stiffer dough, one that can hold itself up rather than spread out. Worth a try – you won’t have as open and light a texture, but you should have a taller loaf. You might give our Rustic Sourdough recipe a try- PJH

  5. sullivantp

    Hi, beautiful baguettes! Say, given the comment above about too-low oven temperature rendering a chewy crust, would it be better to crank the over up to 550 — or is 425 a better cooking temperature? (I’m guessing the answer but 550 works well for me generally.) And do you add any steam or ice cubes while making these?


    Tom – Try baking at a higher temperature if you’d like. The loaves may spring up higher and faster. If you would rather use steam than spraying the loaves with water, that would be fine, too. Let us know how it goes! Elisabeth

  6. karenmtaylor

    Why do you use AP flour rather than bread flour? I made sourdough bread yesterday from the started I got from KAF, I love sourdough but I used 2 cups of bread flour and 3 cups of AP flour. I compared by slice to yours here in the blog and my bread is denser than yours, is that because I used some bread flour?

    Karen, the higher-protein the flour, the more liquid you need to use. You can definitely get a light/airy yeast bread from any protein flour starting with about 10.5%, so long as you adjust the liquid accordingly. A “drier” dough will usually rise less than a “wetter” dough; next time, add a couple of tablespoons additional water, and you should be just fine with this flour mix. PJH

  7. kzchon

    Are the measurements of active dry yeast the same as you would use for saf instant? Somewhere I learned for each tsp. of active dry yeast use 3/4 tsp of saf instant. So 1 tb active would be 2 1/4 tsp. Is this correct? Or can I use Tb for Tb?
    In your cookbooks am I always using saf and not active?
    How much sugar in a recipe then, is it better to use the gold saf yeast?

    Hi – I use the same amount of instant vs. active dry – don’t bother to do the math, as it doesn’t really make any difference in the final outcome, though rising times will be slightly faster with instant when compared to active dry. Our cookbooks state the type of yeast to use – active dry or instant. They’re interchangeable, though, so long as you dissolve the active dry before using. Best to use SAF Gold when sugar is 1 1/2 tablespoons per cup of flour or greater. Can you still use SAF Red? Sure; rising times will be slower, that’s all. Enjoy – PJH

  8. xbaber

    Seeing this post made me want to get a sourdough starter again. I had one and loved using it for waffles. But, earlier this summer, before I became enlightened** and started exclusively buying KA flours, I fed my starter with buggy store-brand flour and had to toss the whole thing. I fed the starter and then a minute later saw a bug in the flour canister. I was so upset and grossed out. All I wanted was to make a loaf of sourdough bread and a batch of sourdough waffles and I couldn’t make either.

    ** I had always looked at the shelf price of KAF and thought, “It can’t be THAT much better than the store brand or the national brand.” Then my store had the KA organic AP flour on closeout, so I bought a bag because the price was quite reasonable and I was hooked. The gluten development was beautiful!

    We’re really very proud of our flour – we’re SOOOOO careful about it. It truly is the best flour in the U.S. I always say, you can’t afford America’s best jewelry, car, or house (I’d assume!) – but you CAN afford America’s best flour. So why not go for it?! Thanks for sharing your experience here – 🙂 PJH

    1. Mary Arthur

      I lived just outside of Bombay (now Mumbai) India for almost a year.

      just sift the bugs out of the flour & try to use it as quickly as possible or store it in the frig or freezer. I remember when weevils were in everything that was let sit for very long!

      The local bakery just ground the bugs along with the flour & by the time we knew those little black bits were actually insect carapice, we already loved the bread!!!

  9. clelumom

    your post is great, love the blog and the baguettes look delicious, but I’m concerned about a couple things. First the dark liquid doesn’t have to be siphoned off, just stir it in and it will add flavor, it’s part of the ‘sour’ flavor. Also, I’m concerned about the picture showing a metal spoon; you should never use metal utensils, bowls, etc with the starter or while mixing up the dough as the metal will kill the starter. It’s ok to bake it in metal pan. And the starter also usually has a sour smell to it naturally, whether it’s bad or not.

    I have to respectfully disagree – stirring sourdough with a stainless steel spoon won’t kill it, as ss is completely non-reactive. Also, the reason I don’t stir in all the dark liquid is I like a thicker sourdough, and a less sour sourdough. The nice thing about sourdough is, as with most yeast baking, it’s “to each his own.” There are many, many different paths to a great loaf of bread. Thanks for connecting here – PJH


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