With this first post, we welcome Andrew Janjigian to The Perfect Loaf. Andrew is a long-time bread baker, baking teacher, recipe developer, writer and photographer who writes a bi-weekly newsletter about all things bread and grain called Wordloaf, and also happens to be working on his first bread cookbook. Welcome!
A quick note from Maurizio. While this post by Andrew is meant to highlight the usefulness of commercial yeast in baking and hybrid doughs, The Perfect Loaf remains dedicated to sourdough bread baking. Without further ado, let’s dive in.
This might be a somewhat controversial topic for The Perfect Loaf, a website devoted to all things sourdough, but I’d like to dispel the notion that sourdough (and the wild yeast it contains) and commercial yeast cannot go hand in hand. Sometimes. In fact, there is actually a long tradition among professional bakers of adding small amounts of commercial yeast (sold in different categories known as “active dry,” “instant,” and “fresh” or “cake” yeast) to sourdough breads to promote good oven spring—a hybrid dough. The addition of yeast can also change the texture, flavor, and keeping qualities of the bread—for better, or worse. You might never have the need or desire to add yeast to your sourdough bakes, but the practice is worth knowing about just the same.
All of which means that adding commercial yeast to a sourdough fermentation is not an unnatural, alien practice.
Sourdough fermentations work via the synergy between two sets of organisms, yeasts and lactic acid bacteria, both of which consume simple sugars that are derived from the starches in the flour. The yeasts mainly make the carbon dioxide that gives bread its volume (along with ethanol and some flavor compounds), where the bacteria mainly make acids, which provide the bread’s signature tang (though they do produce small amounts of carbon dioxide under certain conditions).
There are many different species and strains of both yeasts and lactic acid bacteria in any one sourdough starter, and each starter likely contains a unique combination and ratio of different organisms. But one of the most common and abundant yeasts found in sourdough starters is Saccharomyces cerevisiae, aka “brewers” yeast. And while the strain of S. cerevisiae in sourdoughs is different than the one used to make commercial yeast, they are both the same species. And though the sourdough-specific strains of S. cerevisiae are much better adapted for the high-acid environment they exist in, the strains in commercial yeast can still thrive in the presence of acids, at least for the short durations of a dough’s fermentation.
All of which means that adding commercial yeast to a sourdough fermentation is not an unnatural, alien practice. In fact, in France, where bread baking is a highly regulated industry, bakers are legally allowed to add up to 0.2% commercial yeast and still call the bread a sourdough.
Sourdough yeasts can of course produce all the carbon dioxide needed to give bread loft; still, there are numerous practices bakers use to increase that yeast activity in a purely sourdough culture. To name a few: Regular feeding of the sourdough at room temperature; multiple, rapid levain builds (including the practice known as a “booster” levain, where a high ratio of starter is added to a small amount of flour for a short, warm fermentation just prior to its use in a dough); or reduced levain hydrations. Adding commercial yeast to sourdoughs is just another way to increase the overall density of yeast in the dough to goose fermentation, and can be a useful tool for any baker when used judiciously.
Let’s explore the reasons a baker might choose to add commercial yeast to a sourdough bake.
Benefits to Adding Commercial Yeast to Sourdough Bread
Increased volume
Since yeast makes carbon dioxide, adding a small amount of commercial yeast to a sourdough can provide extra volume in the resulting bread, particularly in the case of breads that are otherwise resistant to springing on their own. My baker friend Jess Porter mentioned that at a place she used to work they added yeast to their cranberry-walnut bread, to overcome the negative effects on the crumb structure as a result of the extra weight of the fruit and nuts.
It’s also a common practice to add yeast to 100%-rye sourdough breads. Rye flour does contain gluten-forming proteins, but it doesn’t form gluten networks like wheat flour does, which is why 100%-rye flour loaves are dense and close-textured. Nevertheless, the yeasts in the sourdough culture do serve to open up the crumb of rye breads as much as possible—without them, rye breads would be sticky bricks. Adding commercial yeast to a rye dough can help guarantee that the bread is dense, but not too dense.
A baker might also use commercial yeast—either fresh “cake” yeast, or instant—in their sourdoughs not to increase volume, but simply to guarantee the desired volume, despite the ups-and-downs a starter can go through from day to day and season to season. Sometimes a starter is firing on all cylinders, and at other times it might be a little sluggish, whether out of neglect or colder temperatures in the bakery during winter months. Adding yeast to a dough when a starter is not at peak activity can provide a degree of loft insurance, ensuring the loaves spring the way a baker expects them to. (Case in point: If you are working with a newly-created sourdough starter that isn’t at peak strength yet—if the internal crumb is tight or the loaf does not spring sufficiently—you might want to add a little yeast to your doughs until it is, to guarantee an open crumb.)
More rapid and consistent fermentation
Adding yeast to a sourdough will also increase the rate of fermentation in the dough, relative to one without it. This can be especially useful in a bakery, where timing is everything. And again, it can provide consistency when a starter or a dough is sluggish, whether through temporary weakness or colder ambient temperatures (and we all know how important temperature is in baking). The increase in fermentation rate is dependent upon the amount of yeast used, of course.
A change in the texture, flavor, and other characteristics of the bread
Increasing the yeast activity in a sourdough through the addition of of commercial yeast has definite effects on the qualities of the resulting loaves, especially when it is used in high percentages. Many of the signature characteristics of sourdough bread come from lactic acid bacterial fermentation on the dough, mainly due to the production of lactic and acetic acid. When the balance is shifted in favor of yeast fermentation (through the addition of commercial yeast, even as little as 0.5%, relative to the total flour weight), lactic acid bacterial activity is dampened, and fewer acids will have formed by the time the dough is ready to bake. This can be a good or bad thing, depending upon what a baker is aiming for.
Fewer acids mean a less sour loaf, obviously—adding yeast can give a milder flavor profile to a sourdough, while still leaving it with some of the tang that only sourdough can provide. But the acids in sourdough also have a strong effect on the texture of a loaf too. Acids strengthen gluten networks, which is why sourdoughs—all else being equal—have a chewier crust and crumb than yeast-raised breads. Adding yeast to a sourdough can result in a lighter, more tender crumb and a crisper crust than the same loaf without it.
Now I like the texture of a crusty, chewy sourdough loaf most of the time, but there are instances where I find this effect especially useful. For example, I much prefer the texture of a sourdough baguette with a small amount of added yeast to one without it—I want my baguettes to be as light and crisp as possible, and commercial yeast helps guarantee this, while still allowing for some of the complexity of flavor that sourdough provides. Ditto flatbreads like focaccia and pita. I find all-sourdough pizza crusts a little too chewy; adding small amounts of yeast keeps them light, tender, and crisp, along with the extra depth of flavor that sourdough supplies.
…I tend to favor using yeast in breads not meant to last long, (again) like baguettes, flatbreads, and pizza.
Maybe the most significant effect of adding yeast to a sourdough is how it changes the bread’s keeping qualities. The reason why sourdough breads keep so much longer than most yeasted ones is also thanks to the acids in the loaf. With fewer acids, a loaf will tend to stale much more rapidly. This effect can be avoided by using a minimal amount of yeast, but it is something to be aware of, especially if you like your loaves to stay soft and moist as long as possible. For this reason, I tend to favor using yeast in breads not meant to last long, (again) like baguettes, flatbreads, and pizza.
Hybrid Dough: How to Add Yeast to Your Sourdough Bread
I’ve been adding yeast to some of my sourdough formulas for a long time now, but I ran some experiments recently to better understand the practice. Most bakers recommend a maximum of 0.2% fresh yeast—or 0.07% instant yeast, the sort most home bakers will have access to—relative to total flour weight, and I found those numbers to be a reliable guideline. This is a vanishingly small amount of yeast: For Maurizio’s Beginner’s Sourdough Bread, one of the recipes I used in my testing, the amount comes to 0.5g instant yeast. (It helps to have an accurate gram scale when working with quantities this small, but in a pinch that amounts to slightly less than 1/8 teaspoon.)
When added at that rate, I found the dough to proof only slightly faster than without it; it was ready for shaping about 30 minutes ahead of the control. The resulting loaves had excellent oven spring and similar keeping qualities to the control, though with a slightly finer crumb, especially between the larger alveoli, and their flavor was a tad less sour. So I think 0.07% instant yeast is a good baseline for general use.
With higher amounts, the rate of fermentation increases rapidly. Using double that amount of added yeast, or 0.14%, halved the length of the bulk fermentation with that recipe, making the loaves ready to shape in just a couple of hours. But the loaves lost something in their flavor, texture, and shelf life, so I think this amount is best used when lightness is the goal or where the bread is meant to be ephemeral, as in a baguette.
I found amounts much higher than 0.14% instant yeast to be excessive, especially when cold-proofing the loaves. A few of them overproofed dramatically in the fridge and had a leathery, tough crust. So I’d recommend caution when going any higher than this amount, especially when you aren’t planning to bake the loaves on the same day you shape them.
As for how to add commercial yeast to your sourdoughs, here’s what I do: If the recipe gets mixed together all at once, I just stir the yeast into the flour as I would any other dry ingredient. If the recipe includes an autolyse, I hold back a small amount of water from the final dough (25g or so), and add it with the yeast (and the levain and the salt) after the autolyse is complete; the reserved water helps to hydrate the yeast so that it can start fermenting as soon as the dough is fully mixed.
Proper fermentation of bread dough requires robust yeast activity, especially if you want good oven spring and an open crumb. Adding small amounts of instant yeast to a sourdough is an easy and effective way to get there, and a practice any baker might want to add to their bread baking toolkit.
What’s Next?
If you’re keen on using commercial yeast in your next bake (or not!), baguettes are a good hybrid dough first bake!
30 Comments
Thanks so much for your inside info! Question re; sourdough + yeast….2 schools of bread baking in our home, my wife does only sourdough while I do only yeast with FMF.
However, I would like to explore the possibilities you mentioned with sourdough + yeast.
Because of gastro benefits, I'm using einkorn berries milled right before mixing.
Do you have any sourdough + yeast recipes that I could start with as a newbie?
I don't at the moment, Steve, but I might include some in the future here!
When I bake Hybrid Loafs, I use 2 gr of “boulanger levure” fresh from my bakery per 450 bios flour T65 + 50 gr rye flour , 100 gr liquid levain, 10 gr of salt and 340 gr of water 20oC! The taste and the results are very satisfying with nice alvéoles! Very interesting article! Thank you!
Love that, Lynda!
I have used tiny amounts of active dry yeast in my sourdough/rye loaves and they are lovely. I haven’t tried Baguettes yet – next on my list. I do prefer my straight sourdough loaves with just my levain ( a perfect loaf recipe). Thanks for the interesting article.
It can definitely help and might make sense in your baking—and that’s the point, it’s all good, do what you prefer and what works for you. 🙂
Thrilled to see my two favorite bread bakers/teachers collaborating! Interested in trying out the addition of a slight amount of yeast to my heavier sourdough bread. Many thanks!
Really great having Andrew here!
Thanks Andrew, this article came at a perfect time! I’m baking raisin/walnut bread today. I added 2 grams of commercial yeast before I finished reading the whole article. Your are correct; it is hard to measure such small quantities with the scale. My Raisin/walnut bread always seems a little wanting in the oven spring. Depending upon results I will probably go with an eighth TSP next time.
I usually use a sub-gram precision coffee scale when I need to measure salt or malt. Would work well with IY, too!
Mauricio, thank you for this article.
I have been baking sourdough bread for five years and I learn everything from your web page. You were and still are my bread guru.
Two years ago I moved from Truckee California to Tennessee and since then I have a problem with the starter. It never raised, it smells badly and after so many trials I just gave up and stopped baking the bread. I was against the commercial yeast.
Well, recently I just missed baking bread again and had this idea to add a tiny bit of the yeast to the starter. Today is the day of making a bread and out of curiosity I checked your web page. Voila this artickle showed up. I feel better now and can’t wait to bake again and see how it goes.
Thank you for your advice and for helping us making the best bread.
Ciao, Andrea! This article was written by Andrew, but I’m so glad it came at the right time for you. As we talk about in the post, there are many ways to bake great bread and all is good!
I can’t remember where I read about ‘the golden age of french baking’- when they’d been doing sourdough for centuries, and then commercial yeast became available, and they fused the use of these two to make their bread. This approx 50 year period ended with industrialisation of bread making, before the resurgent rise of interest in sourdough. Reading in that context broke down my unconscious prejudice about commercial yeast. Today our everyday bread is 100% sourdough, but I cook a variety of ryes, and most use a multi build with both sourdough levains and some commercial yeast- as mentioned above, you need it. I also use yeast often in quick party canapes. What I like about using it it that can preferment quite a proportion of flour, add the yeast and fresh flour near end of process, and the yeast moves very little until it hits favourable temps. Much of they year where I live is far below the 20- 25 dough proving temps ( we have a prover) so this yeast component means I can pre- prepare any baking then when desired, pop in the oven where it does its rise then bake. E.g. I do this in Anastasia Svistunova’s katchpuri adjaruli recipe, an adaption from a staple of Georgian culture, found in Jerry Hamelans book “Bread’. (It’s a delicious, fun, crowd pleasing dish for fingers- on sharing. nom nom nom.) Yeast is a baking tool like any other, it’s not my favourite tool, but it has it’s place. Also, thank you Mauricio- I know you do it because precision is called for, but thank you anyway for using metric weights.
Fantastic comments, Amanda, and right in line with our sentiments here. Like you said, it’s another tool in your baking arsenal, and while it may not be in everyone’s cupboard, there’s nothing wrong with it if it is 🙂
Andrew & Mauricio~ Thank you so much for this excellent article—I no longer feel like I’m cheating by adding some yeast!
My own sourdough journey began with a recipe that included over 2 tsp of yeast but soon I found TPL and other sources that emboldened me to eliminate the yeast, with inconsistent results for this once-a-week home baker, and lately I’ve been adding in 1/4tsp or less of yeast with great results!
TPL and 100% sourdough has made me a
much better baker, but a little yeast has made much better loaves. Thanks again!
So great to hear we’ve been a help. When Andrew proposed this article I was first a little hesitant, but after reading it (and talking to many other bakers), I realized this would be very helpful to the many IY bakers out there. Bread baking doesn’t have to be all sourdough or not 🙂
Hi! I remember seeing in Nancy Silverton’s Breads From La Brea Bakery, she uses yeast in some of her sourdough breads, esp. those with whole wheat. And in the Tartine book, I believe there is a section that covers using yeast (as a poolish) and a levain. So it’s out there!
Absolutely!
Hi Andrew, Near the end of the article you say, “I hold back a small amount of water from the final dough (25g or so), and add it with the yeast (and the levain and the salt) after the autolyse is complete; the reserved water helps to hydrate the dough so that it can start fermenting as soon as the dough is fully mixed.”
Do you mean “the reserved water helps to hydrate the yeast so that it can start fermenting…” ?
Fixed, thanks for spotting this!
How does adding yeast change the nutritional profile of sourdough bread?
A great Q and there are so many factors it’s really hard to say, Monica. With all of my research and reading, I’ve found that longer fermentation times help make ingredients more bioavailable and to also breakdown gluten, but I dont have any hard data on just how much time is needed to accomplish this. Personally, I feel if bread is given a reasonable amount of fermentation time (i.e., not in 2 hours!) and you have minimal ingredients, whether it’s sourdough only or a hybrid, it’s healthier than industrially processed bread. That’s my two cents!
I generally have used a small amount of commercial yeast in my sourdoughs, without any adjustments in putting the dough together, a scent 1/8 t for things like my Vermont sourdough with some rye in it, and 1/4 t for cranberry walnut, cherry chocolate and other denser loaves. The only times I don’t is when I use 100% white flour. Since I started that practice, years ago, I have had better consistency of product with no lessening of quality.
Great to hear your approach Gary. And I feel this is exactly what Andrew was getting across in his article—many ways to do things!
Great article! Have you ever added yeast to your sourdough bagels? I tried them for the first time and they were phenomenal!
Agreed, this was a great one from Andrew! I haven’t personally, though I know it’s a common practice 🙂
Gosh, there is so much in this thought provoking article.
With a Natural Leaven it is not so much the regularity of feeding, but the fermentation temperature and acidity which gives the advantage to lactobacilli or yeast. Yeast is often added to rye doughs because the two stage leaven fermentation is undertaken at about 30C at which temperature the LABs thrive much more than the yeast. So there is sometimes a need to add more yeast. Additionally a two stage leaven can reach acidities where yeast is considerably slowed down and the LABs continue quite happily. That is the whole point of them, to get the acidity really high.
I am not aware of any data showing adding more yeast ‘dampens’ the LAB activity. They prefer different sugars.
Again, the dough fermentation temperature has a big influence on the balance of these two. Those seeking a sour naturally leavened bread should ferment at temperatures in the range of 28C – 30C where the LABs are more active.
The problem of adding yeast to a naturally leavened bread is that it accelerates the dough development. Bread flavour takes time to develop. So this is working against flavourful bread. It is not the fermentation itself which develops the bread flavour but the reaction between the alcohol from the yeast fermentation and the lactic and acetic acids from the LABs. These reactions are much slower than the fermentation and this is why using less yeast and retarding the dough both allow for slower fermentation with better flavour.
The French historically were pretty awful at maintaining their natural leavens. See ‘Good Bread is Back’ (Not recommended). For this reason a debate started right back in 17th Century France (natural leaven and beer yeast) between the two and a tradition started, in France, of using the two together for better predictability. With modern method and refrigeration I have had no issues at all in having a stable natural leaven which ferments predictably.
Adding – Yeast alone develops very little acidity and even with retarding the dough the acidity only reaches about pH 5.4 whereas a natural leaven can have acidities of 4.4 or even lower. I’s a logarithmic scale so that is about ten times more acid in the naturally leavened dough. So much more acid for flavour development. In the U.S. sour naturally leavened breads are generally preferred. I prefer milder acidity in my loaves. This is easily attained by fermenting the dough at lower temperatures, say 24C / 75F and having a fresh fed natural leaven.
A softer crumb can easily be attained using a sourdough leaven by using some oats, milk and other Functional additives to the dough.
Sorry to have written so much. I hope it adds to the discussion.
Great article.
I was under the impression that fermenting for longer at lower temperatures leads to a more sour dough, since it allows for more acid build up by the time the year fermentation is approaching completion. You indicate the opposite, or did I read it wrong?
I love how you included a picture of your baguettes, to show that you can get a “light and crisp” texture with 100% sourdough as well 😄
It’s all possible! 🙂