Food Failures: Rise Your Bread Baking Skills With Science

34:48 minutes

Flour, salt, yeast and water are the basic ingredients in bread that can be transformed into a crusty baguette or a pillowy naan. But what happens when you get a sticky sourdough or brick-like brioche? Chef Francisco Migoya of Modernist Cuisine breaks down the science behind the perfect loaf. He talks about how gluten-free flours affect bread structure, the effects of altitude and humidity on dough and how to keep your sourdough starter happy.

Plus, amateur baker and “Father of the Xbox” Seamus Blackley describes how he baked a loaf of bread from an ancient Egyptian yeast. He chronicled that journey on twitter, which you can see below. (BONUS: Scroll down for a Chocolate and Cherry Sourdough recipe!) 

We asked you to tell us about your bread woes and here’s one we could help with!

This happens because:

Map of the United States representing different boiling points of water in Colorado and Florida
Designed by Andrea Corona

Chocolate and Cherry Sourdough Recipe

From The Modernist Bread cookbook courtesy of The Cooking Lab

By adding cherries, we have taken the beloved combination of bread and chocolate in a new direction. This dough is only moderately sweet; the natural sourness of the dough tempers the sweet character of the inclusions. Given how many taste testers were waiting when these loaves came out of the oven, it’s a captivating combination. As a bonus, the bake-proof chocolate chips remain melted for a good while (while still holding their shape), adding to the indulgence of each bite.

Cherry and Chocolate Sourdough Slice
Credit: Modernist Cuisine

Total Time: Active (yeast) 27 minutes / Inactive 20 hours, 26 minutes
Desired Dough Temperature: 24–26°C / 75–78°F
Difficulty: Moderate
Ovens: Home
Yield/Shapes: 1 lg boule (1.00 kg)


  • 230g mature liquid levain
  • 185g water
  • 16g instant dry osmotolerant yeast
  • 225g bread flour
  • 30g cocoa powder
  • 15g brewed espresso
  • 7g fine salt
  • 160g bake-proof dark chocolate chips
  • 160g dried cherries

General Directions

Mix: Combine the levain, water, and yeast in a bowl; add the flour, cocoa powder, and espresso, and mix to a shaggy mass; autolyse 30 minutes; add the salt, and mix until homogeneous; transfer to a lightly oiled tub or bowl, and cover well with a lid or plastic wrap.

Bulk Ferment: Bulk ferment, covered, for 4 hours at 21°C / 70°F; perform 6 four-edge folds (1 fold every 30 minutes after the first hour); after the first fold, add the chocolate chips and cherries; mix with your hands using a squeeze, pull, and fold-over motion; rest the dough, covered, for 30 minutes after the final fold; check for full gluten development using the windowpane test.

Pre-shape: Begin shaping the boule.

Rest: 20 minutes, well covered.

Shape: Work the boule into its shape.

Final Proof: Proof for 12 – 16 hours in the refrigerator, well covered.

Score: Score with a cross across the top; be mindful that the blade can catch on the inclusions; transfer to the base of a preheated cast-iron combination cooker, and cover with the preheated lid.

Bake: Place the pan into a 260°C / 500°F oven; drop the temperature to 245°C / 470°F, and bake for 45 minutes with the lid on; remove the lid, and bake for an additional 10 minutes.


  • Multiply the recipe by two if needed.
  • Consume within 2 – 3 days, or freeze for up to 2 months.
  • Be sure to flour baskets / couches well because this dough tends to be a bit wet and sticky.
  • If you don’t want to cold-proof your dough, you can proof it at 27°C / 80°F (65% RH) for 5–7 h or at 21°C / 70°F for 6 – 8 hours.
  • When mixing, the cherries tend to cluster. Break them apart prior to adding them to the dough.
  • You can measure 1/16 tsp by measuring 1/8 tsp and dividing it in half.
  • If you can’t find osmotolerant yeast, you can use instant dry yeast and increase the final proofing time by 20–30 minutes.

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Segment Guests

Francisco Migoya

Francisco Migoya is the Head Chef at Modernist Cuisine. He is also the co-author of Modernist Bread (The Cooking Lab, 2017).

Seamus Blackley

Seamus Blackley is an amateur baker and physicist. He is also the inventor of the Xbox.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. Fall is officially here. And for most people, that means that the leaves are changing, the weather is cooling, time to go out and rake those leaves up. But, you know, to other people, It’s bread baking season.

Yes, the basics of bread are flour, salt, water, and yeast. You know that. Depending on how you combine those key ingredients you can get a crusty baguette or a pillowy piece of naan. But for you home bakers, you know it’s not always that simple. I can tell from my own experience.

And have you encountered failure to rise that gives you a brick like loaf? Or maybe you’ve made tortillas that come out like mounds of squishy dough? Nothing you want to taco about. Myths about bread baking abound. How many of them are true?

Do you need pure water to bake? Can you use old flour? Is the Dutch oven method a way to get around a home stove not quite up to professional standards? Yes, this is our food failure segment. My next guest is here to answer your bread food failures questions with the science behind getting this carb-loaded loaf right.

Let me introduce Francisco Migoya. His head chief– he’s head chef at the Modernist Cuisine, and co-author of the book Modernist Bread. Welcome to Science Friday, Dr. Migoya.

FRANCISCO MIGOYA: Doctor. It’s great to be here. Thank you.

IRA FLATOW: Did I just elevate you?

FRANCISCO MIGOYA: You did. Chef is fine. Or just Francisco.

IRA FLATOW: OK, Chef Migoya, or Francisco. Let’s talk about it. Modern Cuisine, where you work, it’s all about the science of cooking. How much science is there in the perfect loaf of bread?

FRANCISCO MIGOYA: It is– you know, for something that on the surface is so simple that, you know, it only has four ingredients, flour, water, salt and yeast, it is possibly one of the most complex systems I’ve ever come across in my life as a chef. And, you know, frankly when we first started to write this book I didn’t think we’d have enough material to even fill one volume because of that. I’m like, four ingredients, how hard can this be?

And, you know, five volumes later, we still had a lot of questions. We still– we had to cut recipes because we ran out of space. And there was just this world, this can of worms, that– or rabbit hole, however you want to put it, that the world of bread is. Everything about it is incredibly fascinating. And from a scientific perspective, there’s just so much to learn about it.

IRA FLATOW: Now one of the– I want to get one of the big topics that people talk about, because it does effect so many people when they talk about bread, and that is gluten. What is gluten, scientifically speaking? And how do you make bread without gluten?

FRANCISCO MIGOYA: So gluten doesn’t exist in flour, just to begin with that. And that’s something that’s important to understand. Gluten is something that occurs when two proteins that are in flour– and those proteins are glutenin and gliadin, when they come in contact with water then gluten begins to form. And gluten is the– it’s a stretchy protein that– basically it’s what we like about bread. It’s what gives bread it’s chew. It’s what makes it elastic. And it’s also the thing that celiacs have adverse reaction to.

And so when people tried to replicate or make gluten free breads the holy grail is trying to replicate that texture that gluten gives us, that pleasant stretch and that chew that we associate with good bread. And that’s very hard to do. Because when you’re making gluten free bread, essentially you’re working with flowers that contain zero potential for making gluten. And so how do you get chew out of rice flour? Oat flour? You know, all of these different flowers that are used often in combination to try to replicate as close as possible that texture that we get from gluten?

IRA FLATOW: We have that question, actually, a Voxpop from Carey– David from Carey in North Carolina asked us this question.

DAVID: My wife loves to make challah for the holidays. Unfortunately, both of us are gluten free and so the challah is mainly eaten by our guests. And so we would love to be able to have a recipe to make gluten free challah that really works.

IRA FLATOW: Francisco, is that possible?

FRANCISCO MIGOYA: I mean, you have to manage your expectations. The first thing is, you know, I would love to say you can totally replicate challah. But challah in and of itself is a very low moisture dough. So it’s in– even with a normal wheat flour base challah it’s a little bit hard to handle, because it’s on the– I guess the stiffer end of the spectrum.

And so to try to replicate that one to one with gluten free is– we have– in our book we have basically a replacement for flour. It’s a mixture different flour. So you can utilize the one to one as a replacement, but you handle it differently. You almost have to handle it like clay. So in that sense, it almost might be easier to form a bread with gluten free challah than it is with regular challah. But again, it’s that chew and that softness that we’re looking for is– it’s a little bit harder to achieve, but you can get close to it.

IRA FLATOW: What about bread that you don’t knead? We’ve heard about no knead recipes. Does kneading activate the gluten?

FRANCISCO MIGOYA: Well, kneading accelerates gluten formation. So if you– the no knead technique is pretty brilliant. I mean, it’s basically just combine water and flour. And what happens when you do that, you know, you’re hydrating those two proteins I mentioned, gluten and gliadin. It’s a chain reaction you can’t stop, basically. Now if you want a fully developed dough, meaning a strong dough, you’re going to have to wait if you don’t want to mix it, if you don’t want to knead it, if you don’t want to put it on a mixer.

If all you did was combine these two, water, and flour, and a little bit of yeast, and salt, you have to wait a good 18 hours or so for the dough to actually be strong enough to be manipulated and so that you can bake it and get a nice, chewy, crusty loaf. Machines and mixing by hand, or kneading by hand, what they do is they accelerate that hydration. And so the gluten bonds, those chains develop a lot faster. So it’s all– it’s a matter of time. Intensity versus time is basically the key.

IRA FLATOW: You know, for bread you hear that the secret is in the water, especially here in New York.


IRA FLATOW: There’s the myth– oh, you’ve heard this.

FRANCISCO MIGOYA: You can’t see me, but I’m rolling my eyes so far back in my head that it hurts.

IRA FLATOW: Well, well. OK, let me just tell everybody where I’m heading. You already know where I’m heading, that you only get good bagels in New York because of the water. Let’s debunk that myth, if it is one.

FRANCISCO MIGOYA: Well, and the first thing I’m going to tell you is that I used to live in New York City. And I also had terrible bagels in New York City. How do you explain those? I mean, like, they had the water right? So they had to be great bagels. But I’ve had terrible bagels in New York City.

The first thing we have to understand is that it assumes that every bakery in New York City gets its water from the same exact source. And this is not possible. It’s not true. There’s like five different places where New York City gets water from. And these are all– all these waters have different mineral composition. So it’s not in the water. I’m sorry, New York, but it’s absolutely not true.

And we’ve done many experiments with New York City water. We’ve done experiments with Seattle water. And it comes down to good technique and good execution. Water is not a magical ingredient. This is not to say that you can just use any water. For example, if it’s water that you wouldn’t drink, meaning it smells funny, or it’s slimy, or it’s got an off color, you wouldn’t drink. Also, you wouldn’t make dough with it. So as long as it’s pure water, it’s clean, and it’s something that you would drink, it’s perfectly fine to mix into dough.

IRA FLATOW: All right. Let’s go to the phones, because there is a lot of interest. Let’s go to Athens, Georgia. Clare, welcome to Science Friday.


IRA FLATOW: Hi there. Go ahead.

CLARE: So I have a question about sourdough.


CLARE: I was recently gifted a sourdough starter from Canada, from like 1965. And the family that gave it to me taught me the best bread recipe that was essentially just flour, water, and sweetener, plus the sourdough starter. But I haven’t been able to get my sourdough to be as light as theirs is. It’s always a really dense structure.


IRA FLATOW: So you want to know how to make it lighter?

CLARE: Yeah.

FRANCISCO MIGOYA: There’s a number of things that you could do. The first thing is that you need to make sure that your sourdough is actually vibrant, and happy, and full of life. Meaning that, is it bubbly? Is it– does it smell a little bit like yogurt? Or is it inactive and sludgy? Is it– basically, when you feed it, does it do anything? Because the amount of yeast that will be in it is also going to contribute to how many– basically how much CO2 is going to form during fermentation. And so that’s going to make for a lighter, crumb-structure dough.

I notice– and maybe you just skipped over this, but you said that, you know, there were three ingredients, and you didn’t mention salt. And salt is extremely important. A lot of bread, if you mix it without salt, it just doesn’t taste good, and it just doesn’t form a very good dough. Salt helps with the dough structure.

So maybe it was just an oversight. But anyway, the point is that if it’s very dense it could also be the type of flour that you’re utilizing. It’s a good idea to always utilize strong flowers for making bread. And you might be using a whole wheat flour. And whole wheat has bran and germ. Bran and germ are what are called water loving. Meaning they love to like absorb and pull water away from things. And they absorb a lot of water. So that could be bringing the volume and the density of your loaf down.

So it could be a number of things. And maybe you’re not fermenting it long enough. You’re not being patient. Because that’s one of the key ingredients that– it’s not an actual ingredient, but it’s time. Right? And that’s one of the things that people like just want to speed up. And with sourdough, especially, you can’t, or shouldn’t, rather.

IRA FLATOW: How do you know– I tried– I have a couple of loaves of bread I made up on our website, sciencefriday.com, and I tried to use the Michael Pollan, Sandor Katz method of leaving it to just sit out on the counter without putting any yeast in it, and letting it just collect the air. And I had a lot of trouble getting it to bubble up. I left it there for days. And it just was getting trouble bubbling up. What did I do wrong? How do I make that easier to get that ferment going?

FRANCISCO MIGOYA: So the most important thing to realize is that in the flour that you buy is where you’re going to find most of the yeast and the lactic acid bacteria. Basically, they were on the field, now they’re in your flour. And that’s what’s going to be activated when you add in the water.

So if you mixed your water and your flour and it wasn’t looking very happy, and it wasn’t, you know, like starting to bubble, it could be a number of things. It could be that maybe your kitchen was a little too warm. It could be that maybe it needed a little bit more TLC, meaning maybe you needed to– you needed to feed it a little bit more frequently before you started working on, you know, making your dough.

So there’s a number of things that you can do, as well. I like to combine– like, if I’m starting from zero, I’ll combine water and flour. And a nice trick to add into the equation is to add a little bit of rye flour. The rye flour has a lot of substrates that yeast really loves. And so it really helps to get that yeast activity going. Even chickpea flour, too, is great. Like, a little tiny bit of it is just, yeast goes crazy for that.

And it’s keeping it at a moderate temperature. You want to be around 70 degrees if you can. So if you have a hot room or hot kitchen, maybe find a basement where you can put it in. There’s a possibility maybe the container that you had been holding them in, it was– you know, maybe there was something in it that the yeast didn’t like. But the biggest thing is to just wait and be patient.

So if you do a one to one equal parts water and flour, and it’s in a cool place, between three and four days you should start to see some activity. If you don’t, start over. It’s better to just start over than to try to make something that is not really showing any signs of life to make it work. So that little bit of rye that I said earlier, or that little bit of chickpea flour are really going to get things going for you.

IRA FLATOW: That’s a good suggestion. I’m going to try that on my next batch. I’m Ira Flatow. This is Science Friday from WNYC Studios. We’re talking with a Franciscan Nagoya, who is the head chef at Modernist Cuisine, and co-author of the Modernist Bread Book. I really– it’s a beautiful book. I mean, beautifully laid out. And I thought about, you know, when you go into a restaurant how you– presentation is important in the dish, and presentation seems to be important in your book, [INAUDIBLE] you were laying it out.

FRANCISCO MIGOYA: Yeah. I mean, this is– an important thing to remark is that this is about five years of the lives of 25 people who, you know, we dedicated all this time to writing this book. And so it’s– we’re– most human beings really like to have that visual aspect be appealing. And thus, the success of like Instagram, for example. You have beautiful pictures. People are going to like that.

And so in our book we really make an effort to have beautiful pictures, but also pictures that are maybe from angles you’ve never seen before, or things that you may not have seen, like the inside of an oven. We cut ovens in half. We cut mixers in half. We cut Dutch ovens in half, so you can see how bread is baking inside a dutch oven. So that it’s basically this see through of how things work. And it really helps to show and to make a point across when you can see through things.

We have another beautiful picture of, you know, dough fermenting. You know, what happens– and it’s– and we actually have a video of that, which is a time lapse of how those CO2 bubbles form and how the dough expands. And it’s just amazing to watch. So it’s a different view, and it’s a very, I think, very pedagogical way of showing things as well.

IRA FLATOW: I’m going to play one more cut from our Voxpop listeners. Maybe we’ll answer on the other side, if we don’t have the time before the break. And they’re asking how do we adjust– a lot of people asking how to adjust their bread recipes when they move to different cities.

MICHELLE: I was born and raised in Western Pennsylvania and got pretty good at baking breads. Now that I live in Houston, I have a lot of trouble baking bread. And I suspect it is because of the high humidity. What are some tips that I can use to improve my bread baking skills in high humidity?

IRA FLATOW: Michelle from Houston asking that. Francisco, what do you say?

FRANCISCO MIGOYA: Yeah, so hand-in-hand with high humidity comes what? High heat. Right? I mean, that’s typically, you know, the one, two punch. And it is an enemy of making bread, simply because high humidity, high heat means the dough is going to ferment on you very quickly.

So there’s a few things you can make to adjust for that. And the first is, you know, I would say the ideal case scenario is that you have temperature control. If you have air conditioning, what you’re going to have is a room that is about 70 degrees, which is ideal. But it also helps to dry the air out. Right? Because air conditioners do that. They pull moisture out. But maybe you don’t have it.

And so some of the things that you can do is, when you’re mixing your dough, start with very cold water. And if you start with very cold water what it’s going to do is it’s going to slow down the fermentation process. In fact, if it’s really, really hot in the kitchen you’re working in, some bakeries even keep their bags of flour in refrigeration. So that as it’s mixing and you’re creating this friction the dough doesn’t get too warm.

The other thing that might be happening that she might be having a problem with is that the dough is pretty sticky because it’s too wet because the humidity. So a way around that is to just be generous with the flour when you’re basically shaping your dough. When you’re handling it, don’t be afraid to use excess flour. You’re able to kind of like brush it off before it goes into the oven if it’s too much of it, but it also helps keep things from sticking.

And if you don’t like the flour look some people use oil. They put a little bit of oil on their hands and the work table, and it helps to manipulate and work with the dough. So those are the two things I would do. I would get a thermometer, too. I mean, this is one of the things that can make your life a lot easier is if you’re able to get water out of the tap, and you add a little bit of ice to it. And you start, let’s say at like– with water that’s at about 55 degrees Fahrenheit, or 50 degrees Fahrenheit. This is going to be a way for you to be able to control how your dough is fermenting. And it’s going to give you more time.

And that’s– you know, that’s one of the problems we have. It’s like, if the dough starts to move very quickly and it starts to form very quickly, we kind of panic. Right? So this is one way to control that.

IRA FLATOW: I love controlling panic. We’re talking with Francesco Migoya who’s author of The Modernist Bread Book. We’re going to come back and talk lots more with him. 844-724-8255. You can also tweet us at SciFri. We’ll have a lot more food failure after this.

This is Science Friday. I’m Ira Flatow. We’ve been talking about the science of bread baking with Francisco Nagoya, who is head chef at Modernist Cuisine and co-author of this wonderful new book about bread called Modernist Bread. Our number, 844-724-8255. Let us go take a call. Let’s go to Eileen in New Orleans. Hi there. Welcome to Science Friday.

EILEEN: Hi. Thanks for taking my call.

IRA FLATOW: Hi. Go ahead.

EILEEN: I often like to switch out from the– change flours up a bit. Instead of using all of the bleached white flour, I might want to put in a cup of spelt, or a cup of rye, or whole grain. And oftentimes I have a rising failure when I mess with that. And I’m wondering what I can do in advance to compensate for the changing up the– adding a whole grain flour to my mix.

IRA FLATOW: Good question.

FRANCISCO MIGOYA: Yeah. The first thing I will tell you– and you’re talking in volume measures. So the first thing you should do to avoid any sort of like things up to chance is to get a scale and weigh your flour. Because if you’re adding cups of this and cups of that, I mean, I guarantee every time you measure a cup, it’s going to have a different weight. So the first thing is, weigh your flour.

The second is if you’re adding spelt, that’s fine. If you’re adding like a quarter of the weight of your flour in another flour, that’s fine. But what you want to do is the regular, unbleached flour you do, get a stronger flour. Get something that is going to have– basically it’s going to be the spine that is going to hold everything up. Because when we add other flyers, when we add rye, when we add like einkorn, or any like so-called ancient grains, these grains don’t have a great capacity for developing a dough as strong as wheat flour does. And so, a lot of bakers what they do is they’ll take a high percentage of a strong bread flour and then combine it with other flours, but there’s always that structure-forming flour that helps helps basically everything strong and in place.

So if you’re buying something that says, you know, bread flour, I would say, for example, King Arthur has Sir Lancelot flour. It’s super strong. It’s got like 14% protein. And so it’ll be able to take in a good amount of other kinds of flours and still give you a nice, strong dough.

IRA FLATOW: Yeah, because we had a tweet from Valerie that says, what about adding other things, like tapioca, xanthan, rice, or chickpeas?

FRANCISCO MIGOYA: Well, I mean, you can add that, but not for making a dough stronger. None of those things have any dough forming properties. I mean, if you want it to go like super purist, you can get gluten as a powder. And it’s– I forget whom– oh, Bob’s Red Mill sells gluten flour. And so you’re literally adding strength. It’s like a vitamin B12 shot into your dough.

And, you know, even a little bit– If you add like, you know, 1% of the weight of your flour in gluten, it’s just it’s enough to make a difference and to really make your dough super strong.

IRA FLATOW: There’s a lot of science behind this. Let’s go to our Voxpop. We have Grace from Seoul, Korea had a question about ovens.

GRACE: Hello, Science Friday. I’ve been doing all my baking in a toaster oven. I was wondering if you had any tips or tricks to help make my breads and cookies a little bit better?

IRA FLATOW: Have you ever heard anybody baking in a toaster oven?

FRANCISCO MIGOYA: No. It doesn’t mean you can’t, but that’s super brave to make a brand in a toaster oven, just because it’s– they’re– you know, if a home oven is not so good for making artisan bread, a toaster oven is actually a few steps behind that. The biggest thing I would say is that what you’re looking for is to have like this constant heat, like high heat, on your dough to make sure that you’re getting, first of all, that oven spring, but also, you know, that’s why we like to use what is called a cast iron combination cooker in home ovens. It’s basically a cast iron– it’s two– it’s like a skillet and a pot that fit together nicely, so they create this airtight environment.

So we preheat our oven with those together. And once we’re ready to bake the bread we put it in the skillet part of the combination cooker, score it, and then put the lid on top of it. And so that cast iron not only absorbs the heat beautifully, it’s like this black dense metal, but it also radiates it really nice into the dough, like in a very constant, steady stream. And you have also the benefit that it’s not– that it produces its own steam. So you don’t have to be like doing all these things, like throwing water in the oven, or ice cubes, or all these things that basically create an irregular or inconsistent amount of steam.

Think about this. Every time you open your oven door, you’re opening one sixth of it. That’s a huge amount of space to open because all the heat escapes. But if you have a cast-iron combination getting hot in there, it stays hot.


FRANCISCO MIGOYA: And the thing is, I don’t know how big your toaster oven is, but if you can get like a cast iron pot, or a pot that you can fit your dough into, it’s going to really help bypass all of the issues that these types of ovens have.

IRA FLATOW: I want to bring on another guest who took his home experiments to the extreme. He baked a piece of bread from an ancient strain of yeast, we think. Seamus Blackley is an amateur home-baker. He’s also a physicist, and the inventor of the Xbox, a truly Renaissance man. Welcome to Science Friday.

SEAMUS BLACKLEY: Well, thanks, Ira, and thanks for that crazy compliment.

IRA FLATOW: Yeah. Well, this isn’t your first try using ancient yeast to bake bread. Tell us about how this all came about.

SEAMUS BLACKLEY: Well, like a lot of nerdy guys, I have been baking bread for a long time and got really into sourdough. And largely just because it’s a challenge. And I started to get into these so-called ancient grains, also largely because it’s such a pain to make a decent loaf of bread with them. And, you know, it’s a slippery slope from there. And I found myself collecting yeast in crazy places, and learning a lot about yeast, and different doughs, and techniques, and slid inexorably into another passion of mine, which is Egyptology, when a sample of a supposed ancient Egyptian yeast became available from some brewing friends of mine. So I tried making bread with it. And it was pretty good.

IRA FLATOW: And then there was the discovery about this ancient Egyptian yeast inside a tomb?

SEAMUS BLACKLEY: Well, yeah, that brewers yeast was, you know, ostensibly scraped off the inside of some old brewing pots. And when you scrape an old archaeological sample like that what you’re basically getting is museum dirt. Right? So a lot of people, a lot of Egyptologists, a lot of microbiologists who followed my crazy baking experiment on Twitter basically called me out and said, hey, you don’t know what that is. You’ve got to do better. And so I asked for their help. And together we came up with a methodology for extracting dormant microorganisms from the insides of the ceramic matrix of some of this ancient Egyptian pottery.

I have two partners, an Egyptologist, Dr. Serena Love and a microbiologist, Richard Bowman at University of Iowa, who helped me to develop a non-invasive technique for extracting dormant stuff out of the middle of pots.

IRA FLATOW: Wow. I want to go to the phone call– to the phones to Daniel in Houston, who had sort of a similar experience. Daniel?

DANIEL: Good afternoon. Yes, I do.

IRA FLATOW: Tell us about it.

DANIEL: Well, I’ve been baking with sourdough for a little over 10 years. And a neighbor of mine offered me a strain of sourdough starter that he said was ancient Egyptian. And it turned out pretty good. I was just wondering, how could you prove that that’s actually an ancient strain of yeast there that I got? I mean, it could be anything. I couldn’t tell. So what’s the science behind all that?

SEAMUS BLACKLEY: Well, it’s a fear thing. Sorry, Ira. It’s– first of all, you need to be sure that you’ve collected this sample from a place, from a vessel, where there’s actually a chance that the yeast and other microorganisms in a bread starter could have survived, because they go dormant if they don’t have water and food. And it’s not the outside of a pot. It’d be the inside. After you use a pot a bunch, you drive some of these microorganisms into the ceramic itself.

And then after you collect it you have to, you know, very carefully and with good microbiological technique, keep it sterile, keep other modern organisms away from it. So when we feed these things in the lab we use these lab feeds. And when I bake with them my kitchen looks kind of like a laboratory. We have sterilizers, and UV lights, and flames. And we sterilize all the flour that we feed the sample with so that we’re sure that we don’t contaminate the original sample with anything new. So it’s really just being careful, washing the stuff a lot, and, you know, being careful you don’t cough into your starter.

IRA FLATOW: And how did you cook it?

SEAMUS BLACKLEY: Well, I’m a physicist. So I have the sort of thing that I do where we try a single thing at a time and make sure we know what we’re doing. So I started out making a normal, sort of modern, Western, French style bread with it in a basket, just to see what the yeast was like and see if it would work. And I fed it emmer flour, which is the flour that we know the ancient Egyptians used, at least in the Old Kingdom when they were building the pyramids, to make bread.

And it really liked it. It developed instantly. It behaved beautifully. And as those of your listeners and your other guests know, baking with these old flours is very hard to do. You have to it takes years of practice, years of horrible, brick-like loaves. But this stuff just took off on this ancient flour, which gave me confidence, incidentally, that it was genuine.

So I just slowly learned how to bake with it. And then increasingly started to bake using traditional, ancient Egyptian techniques, which don’t use an oven. So it’s very different from what we think of when we think of baking bread.

IRA FLATOW: Francisco, what do you think of this whole escapade here?


FRANCISCO MIGOYA: I have so many questions, but it’s– I mean, how do you– what type of yeast strain was this? Do you know what strains you had?

SEAMUS BLACKLEY: Yes. So we are currently doing DNA and RNA analysis on our samples. We’re continuing to collect samples. So part of the deal is, to know that you have something, you have to have a lot of statistics. The science thing, you need to make sure that you interrogate a whole bunch of pottery. And you find a signal on it, which is a truly potentially ancient organism. Then we can look at its DNA and get clues as to its age from the microbiology itself, from the RNA, and see what it’s related to.

Finally, you can look and investigate the behavior of these things as you see it and collect them and the strains that we think are suspect. The guys that we think are actually old behave differently in a lot of different ways from modern yeast. And most modern yeast that we collect even in nature are related. In fact, it’s greatly proliferated everywhere in the world. These act a little bit differently, and so are suspicions is they’re not related, but we don’t know yet. We have a lot more work to do.

IRA FLATOW: Good luck to you. Thank you for sharing your experience with, Seamus.

SEAMUS BLACKLEY: Thanks for having me on.

IRA FLATOW: It’s great to have a geek who’s a baker at the same time. Seamus Blackley is an amateur home-baker, and also physicist, and inventor of the Xbox. With me is Francisco Migoya, who is head chef at Modernist Cuisine and the co-author of The Modernist Bread Book. And just to remind you, there’s a recipe from the bread book, Modernist Bread, up on our website at sciencefriday.com/breadfails. So if you’d like to get in on that. Let me see if I can get a phone call or two more before we have to go. Let’s go to Dayton in Tallahassee. Hi, Dayton.

DAYTON: Howdy. Thank you very much for having me on. My question is about, so then, on the topic of yeast– yeast, of course, provides the carbonation and all that in the bread. What about different flavor profiles? Or different species of use being explored rather than cerevisiae– I believe it’s name is cerevisiae– for bread?

IRA FLATOW: Let me– before you answer that, let me remind everybody that I’m Ira Flatow. This is Science Friday from WNYC Studios.

FRANCISCO MIGOYA: I love that he asked this question, mostly because when we think about sourdough we have this like tendency to zero in on the yeast. And the dominant strain of yeast in most sourdough starters is going to be saccharomyces cerevisiae, which is basically the yeast that really likes to eat starch. And that’s the yeast that you’re going to find in the fields where wheat grows, where grains grow. It’s the yeast that when you grind up your grains to turn them into flour it mixes into the flour. And, you know, it’s what provides us with fermentation. But a lot of people seem to forget about a very important component of sourdough starters, which is the lactic acid bacteria.

And the reason why it should matter to us more than the yeast is because lactic acid bacteria actually outnumbers yeast 100 to 1. That’s not a little bit. That’s nothing to frown down upon. I mean, it’s 100 to 1. And the reason why this is also important is because the lactic acid bacteria is what’s going to determine the flavor profile and the personality of everybody’s sourdough starter. Everybody’s is going to be different because of whatever that mix of lactic acid bacteria is in there.

So you can change the flavor and adjust the flavor of your sourdough starter simply by, first of all, what temperature do you keep it at. Why? Because some lactic acid bacteria prefer colder temperatures. And so then they secrete a particular flavor of acid more. The ones that prefer the colder temperatures secrete more yogurt like flavors into your sourdough starter. Where the lactic acid bacteria that is, it’s basically home fermentative, that prefers a hotter temperatures, what they secrete is more of like the acetic acid, which is that acid that you associate with vinegar. So you get these really pucker up sourdoughs with that.

So you can train your sourdough like a pet, which it’s this remarkable thing. I mean, these microorganisms adapt. And they adapt, and they thrive, you know, depending on what conditions they’re in. And you can also adjust the flavor by basically how often you feed it, you know, how much flour you feed it, what mixture of flowers you’re feeding it. But very important, everybody with your sourdough, try to feed your sourdough more or less at the same time every day, because it’s like a pet. And it gets used to that schedule of feeding. And it will know how much food it has for how much time. So train it to learn that curve.

And the second thing is try to keep it more or less at the same temperature every day. Don’t– these temperature fluctuations are really going to kill your sourdough starter if you don’t treat it right. I keep mine in a wine fridge. Because my wine fridge is at 55 degrees Fahrenheit. And the yeast is just happy enough. And I get that yogurt flavor profile from it that I prefer over that like super acidic sourdough.

IRA FLATOW: Wow. That’s interesting. Well, let me see if I get a quick tweet from Teresa, who says, love to know why my pizza crust will get really crispy, but doesn’t brown. I use zero flour– double zero flour and semolina mix.


IRA FLATOW: I got a minute for you to answer that.

FRANCISCO MIGOYA: Yeah, typically when pizza crusts don’t brown it’s because they over-fermented. If you think of what is browning and what is creating that mired reaction, it’s the sugars that are in the starch, which is basically sugar. It’s a complex sugar. If the yeast has depleted this food, this sugar, and there’s no available sugars, it’s not going to brown. You’re not going to get that nice, mired reaction. So typically when you get a really pale loaf it’s because your dough has fermented too long. So it’ll bake, it’ll crisp up, but it won’t have that nice, brown color that we usually like to associate with pizza.

IRA FLATOW: There you have it, Francisco Migoya head chef at Modernist Cuisine, also co-author of The Modernist Bread Book. And there is a recipe from modernist bread on our website. It’s sciencefriday.com/breadfails. And the Modernist Cuisine book is just excellent. Thank you, Francisco, for taking time to be with us today.

This was great. Thank you. And we want to hear your voice on Science Friday. We have an app, the Science Friday Voxpop app, which lets you record your own voice so we can play you on the air. And we want you to download the app. When we need your contribution for an upcoming show.

Tell us, have you moved or thought about relocating because of climate change where you live? Have you moved or thought about relocating because of climate change where you lived? Let us know on the Science Friday Voxpop app, wherever you get your apps.

And it’s really great. You can– we’ve been playing some of them on the show today, and we really would like to hear. One more time, tell us have you moved or thought about relocating because of climate change where you live? That’s about all the time we have for now. Hope you got some great– I got some great bread making tips today. Hope you did, too. I’m Ira Flatow in New York.

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Alexa Lim is a producer for Science Friday. Her favorite stories involve space, sound, and strange animal discoveries.

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