This is a transcript of the Gastropod episode, Say Cheese!, first released on March 23, 2015. It is provided as a courtesy and may contain errors.

HEATHER PAXSON: The very first question we were to address was how is cheese made, which I think the postdocs who put together the questions for us thought this was a straightforward question to begin with, but we went round and round, because it turns out you can’t explain how cheese is made without knowing what you mean by cheese.

CYNTHIA GRABER: You’re listening to Gastropod.

NICOLA TWILLEY: The podcast where we wrestle with the really big questions. Like what is cheese anyway?

GRABER: Well, not exactly. It’s more like here we are putting out an episode about cheese history and cheese science, and even how to put together the ultimate cheese plate, and it turns out we don’t actually know what cheese is, but we’re getting ahead of ourselves. I’m Cynthia Graber.

TWILLEY: And I’m Nicola Twilley, and the lady who opened up this whole Pandora’s box of how to define cheese was Heather Paxson.

GRABER: She is an anthropologist at MIT. She’s been studying cheese and the people who make it. She was also part of an American Academy of Microbiology meeting last summer in June 2014. They were talking about the role of microorganisms in cheese. There’s a paper that came out of that meeting. We have it for you on our website. So Heather organized a cheese tasting for us to help us get to the bottom of what cheese actually is.

PAXSON: So for instance, we were of course there to talk about microbes in cheese, and, in fact, the FAQ that came out of it is titled “Microbes Make the Cheese.” And in many of the cheeses that first come to mind, for instance the cheddar that we have here on the table, it’s a natural cheese. It is developed first by the bacterial fermentation of milk that allows for the curds to then coagulate, and then develop the natural rind on the outside, which contributes to the flavor and the character that we attribute to a Cheddar as opposed to another sort of cheese. So that was the kind of cheese that I think everybody had in mind, but then as soon as we started talking, people said, “Well, what about ricotta? What about paneer? What about American cheese?”

GRABER: That’s because ricotta, paneer, a goat’s milk chevre, those don’t contain microbes at all, and American cheese? We’ll get to that crazy process later.

TWILLEY: Yeah, I feel like this is the kind of thing that people fight wars over or at least expensive legal battles. So what about ricotta? Is it a cheese?

PAXSON: Ricotta is definitely a cheese.

TWILLEY: Phew, case closed.

GRABER: Wait a second. The plot thickens.

PAXSON: There’s a difference in approaches among the different working groups that we had at our meeting, and so we really set out to come up with a universal definition, and that universal definition is basically that cheese is dehydrated and aged milk.

GRABER: That doesn’t sound nearly as attractive.

PAXSON: It really doesn’t.

GRABER: In the end, basically, Heather said that the scientists decided there were three different methods for making cheese, and the end products of each of those three methods counts as legit cheese. So you can use acid to clump milk proteins into curds, that’s the acid method for things like cottage cheese, or you can use acid and heat, that’s ricotta and paneer, or you can use rennet and microbes, like for Cheddar or brie or all the other things we think of as cheese. Rennet is an enzyme that traditionally comes from the stomach lining of calves, though we’ve figured out other ways to make it these days.

TWILLEY: So, basically, to get to cheese, you need to separate milk into solids and liquid, and you have three choices for how to do that.

GRABER: It’s funny, though, if you taste ricotta…

TWILLEY: Uh-huh, wait a minute. Am I finally going to eat something on this show?

GRABER: Not only that, we are going to eat it together in different states using a bit of complicated engineering, with us buying the same identical cheeses.

TWILLEY: Poor us, double the cheese.

GRABER:  It takes like milk.

TWILLEY: It tastes like cream. But, you know, it’s very, it is very delicate in flavor, like there is none of that… if you told me this wasn’t cheese and you asked me to believe it was just, sort of thickened cream, I would accept that definition.

GRABER: Yeah, me too.

PAXSON: Yeah, yea,h that’s interesting. I mean it’s fresh, right? It also hasn’t been aged, so the microorganisms… I mean, in a hard cheese we get the flavor from the microorganisms breaking down the enzymes and the fats in the milk, releasing flavor compounds. And that doesn’t happen with the ricotta because it’s fresh and we eat it right away. And there’s no breaking down of the component parts, so it’s as good as the milk is.

GRABER: What’s crazy here is that the ricotta we just tasted might be something like the very first cheeses ever made. Though those are made from sheep or goats milk. I spoke to a cheese scientist and historian. His name is Paul Kindstedt. He’s at the University of Vermont. He described the origins of the very first cheese.

PAUL KINDSTEDT: Well, the earliest evidence, and this is really fairly recent work that’s been done because of new analytical methods, technologies that have enabled sort of archaeo-chemistry to be carried out at levels that were never possible before. But the earliest evidence for cheese making and large scale dairying goes back to about 7000 to 6500 BC.

TWILLEY: We are going back to the very dawn of cheese. But before we go there, we’re going to hear some of your cheese stories.

[CLIP: Singing in old commercial]

JENNY MORBER: I’m Jenny Morber and here is my cheese story. My dad actually worked for Kraft Foods back when he was a young engineer hurting for money. His job, at least from the stories I’ve heard, was to taste products that might have gone a bit off to see if he could tell what had gone wrong with the processing. Needless to say, we didn’t have much Velveeta in the house and he never ate mayonnaise. But we didn’t have much else in the house either, cheese wise. I still remember the day I tasted brie from a supermarket in France. It was like “Holy shit, cheese can taste like this?” It was like I put on a pair of glasses and could suddenly see the leaves. Yeah, I gained 15 pounds that summer.

MIKEY: Hello, Gastropod. This is Mikey in Gainesville, Florida. I was calling to say that I absolutely adore cheese. I was delighted when I discovered from my English wife that cheese is actually a course in a proper dinner.

TWILLEY: So, speaking as an English wife, I can say that this is just one of the many ways in which we are the best. Here’s another story, Emily Lo Gibson told us she started loving cheese thanks to Wallace and Gromit. But it didn’t turn into a full-on addiction until she spent a semester studying abroad in Paris, enjoying her host family’s nightly cheese course.

[CLIP: Wallace and Gromit]

WALLACE: I could just fancy some cheese, Gromit. What do you say?

GROMIT: Don’t forget the crackers.

TWILLEY: Back to the history. Cynthia, transport us back nearly 9,000 years to the very, very, very beginning of cheese.

GRABER: Here is what was going on. But actually I have to start back even earlier, by about 1,000 years. Okay, so we’re in the Fertile Crescent. It’s the region that curves down through the Middle East from Egypt on one side to Iraq on the western fringes of Iran, and as far north as about southern Turkey. And why then? The climate had changed. It was the end of the last major Ice Age. Things are warming up. And people started growing all these crops. It’s basically the dawn of agriculture. They start settling down and growing cereals they’ll eventually domesticate. And the local wildlife starts showing up to snack on the crops.

TWILLEY: By which you mean things like goats and sheep.

GRABER: Right, and, as you know, these animals can provide milk. The only problem is that it was basically of no use. Everybody was lactose intolerant except for the babies.

KINDSTEDT: Almost certainly in the early stages, and we don’t know when the first experiments with milking for human consumption took place. But almost certainly the milk was harvested for very young children because humans would be very well aware that young children survive on milk until they’re weaned.

TWILLEY: Okay, so now we have the start of dairying. But what about cheese?

GRABER: So it turns out that cheese begins because of the very first human-created environmental disaster.

KINDSTEDT: The soil fertility has been driven to nothing. Deforestation, erosion, lots of evidence of sort of a catastrophic environmental failure brought on by too many people and unsustainable agricultural practices that just couldn’t support the population any further.

GRABER: But what the land could support was all those animals that were hanging around.

KINDSTEDT: And it’s amazing how little it takes to raise—in terms of vegetation—it takes to raise sheep and goats.

GRABER: And then one other thing happened at the same time that kickstarted our whole incredible love affair with cheese: the Neolithic people invented pottery.

KINDSTEDT: Think about, you have to milk into a container, and there were very limited options for containers in the Neolithic. Pottery opened the door to collect milk on a larger scale and store it. And in the warm environment of the Fertile Crescent region that milk would have almost immediately and very quickly, in a matter of hours, coagulated because of the natural lactic acid bacteria that are always present in milk environments. And so cheese acid coagulated curds or fresh acid cheeses would have just happened almost instantaneously.

TWILLEY: It’s ricotta.

GRABER: Or more likely chevre because goats were domesticated before cows. They were a lot smaller and friendlier.

TWILLEY: Cynthia, I know you are the one speaking to the expert here, but what I had always heard is that the very first cheese came about because a nomadic herdsman was riding around carrying milk in an animal’s stomach like some kind of proto-Thermos and of course, as we said earlier, the stomach has rennet in it. So as he rode the milk coagulated, and by the time he stopped for a drink his milk had turned into cheese.

GRABER: And that’s exactly what I thought. I even wrote about it in a science story on cheese more than a decade ago. I wrote that story. But it’s totally not true because the herdsman would have been lactose intolerant. That milk before the cheese came around, it was only for the kids.

TWILLEY: Oops.

GRABER: Yeah, I was wrong. Sorry. But I just saw another article a week or so ago and it had the exact same myth. So here we are busting the myth.

KINDSTEDT: The Neolithic peoples would have been confronted with this change in the phase of the milk, magically. Going from a liquid to a gel, sort of a pudding-like consistency. And if they broke up that gel, they would have seen that a liquid would separate from it and a solid curd material would be, could be recovered. And at some point, probably very quickly, some adventurous adult tried some of this curd and found that they could tolerate a lot more of it than they could milk because the lactose content is reduced by about 80% in the process of coagulation, and whey separation, and fermentation.

GRABER: And here’s what’s totally crazy. Eating cheese changed their DNA.

KINDSTEDT: Cheese making, in particular, made dairying, that strategy, available not just to very young children, which Neolithic peoples had been dabbling with for some time. We don’t know for how long. But now suddenly dairying became a viable survival strategy for the entire population because adults could consume cheese. And therefore dairying became part of life in general. And milk was available and around. And children, newborns, were being exposed to milk far more frequently which ultimately selected for, through random mutations, those children that could tolerate lactose into later childhood and then into adulthood. It’s an absolutely stunning example of genetic selection occurring in an unbelievably short period of time in human development. I mean this is really stunning, stunning stuff—that humans could evolve and develop this tolerance to lactose so quickly after the onset of dairying. It’s really a wonder of the world and it changed the world forever. It changed Western civilization forever.

TWILLEY: That’s really kind of amazing. But you know that means that those cheeses that were causing Heather and her microbiologist buddy such a headache—the acid-coagulated cottage cheeses and the acid heat ones like paneer and ricotta—so those are actually the original cheeses.

GRABER: And really the most important ones. I mean they literally changed our DNA forever and what’s more they changed our entire civilization. Cheese ends up being the foundation of cities and even writing which kind of blew me away. Because it ends up being part of the very first religion. And so this is happening in what is now modern day Iraq.

TWILLEY: Okay, so these are Sumerians.

GRABER: Exactly, fast forward about 3,000 years. People have been eating cheese for a while. They’ve created the first city state. It’s called Uruk and it runs on cheese. And so of course their religion now runs on cheese. Here’s a tale Paul told me about this goddess named Inanna. She has to choose between two suitors, there’s a farmer who wants to marry her and then there’s the shepherd Dumuzi.

KINDSTEDT: And Dumuzi makes the argument that what I can offer is so much better than what the farmer can. I have milk, and I have cream, I have butter or butter oil, and I have cheese, and I have flavored cheeses, and I have yogurt, and fermented milks and I produce so much surplus of these wonderful products that even after supplying you with all that you want and desire I’ll have extra left over to give away. I can really keep you happy, sweetheart. The long and short of it is, Inanna agrees to marry Dumuzi and gets won over because she really values the dairy products.

GRABER: And based on that belief, it starts a thing where people gain favor with the goddess by bringing her cheese and butter at the temple every day.

KINDSTEDT: And the government, basically the king and his ruling elite, working in conjunction with the temple priests, gained control over shepherds and create a whole contractual system to make sure that there are shepherds that take care of the sacred flocks and the sacred herds, overseeing a system where dairy products, cheese and butter would be coming into the temple every day and stockpiled and then go through a series of rites or rituals in honor of Inanna, and then they would be redistributed to the civil servants that were running the government.

GRABER: Managing all that cheese was a bureaucratic nightmare. So what did they do? They invented writing.

TWILLEY: To keep track of the cheese! It’s like the original management system. I love it. Who moved my cheese? But 5,000 years ahead of its time.

GRABER: I knowm it’s a crazy story. When I was reading Paul’s book, I was sitting next to a friend and I literally exclaimed, “The city state was founded on cheese!” I told Paul that story when I spoke to him. He kind of hedged. He said there were other agricultural products as well. But cheese and butter did play a major role.

TWILLEY: But as we discussed with Heather, cheese has come a long way since those early days. So, how did we get from that ricotta to all the Cheddars, and the Bries, and the Emmental that we know and love?

GRABER: And love so much. We’re about to jump ahead again a few thousand years to the Middle Ages. That’s like the golden age of cheese invention.

TWILLEY: And there were a lot of things to figure out along the way. Trial and error, and in fact, as it turns out, cheese can still be quite a complicated thing to figure out today. So we heard some really funny stories about cheese mistakes from you guys. Roz Cummins was volunteering in the Boston food co-op many years ago and there was a hippie guy there who she worked with.

ROZ CUMMINS: And he said, “Hey man, we just got some really good Gouda in from Amsterdam. Want to try it?” And I didn’t know what Gouda was but I figured if it had just come in from Amsterdam, and he was a hippie, he was offering me some sort of hashish or something. And I said, “Oh no, thank you, I don’t do drugs.” And he bent over double laughing and said, “Man, Gouda is how they say Gouda in Amsterdam.” So I had just turned down some fine imported Dutch Gouda.

GRABER: And, in another cheese mistake, Alana Lubin wrote to say that she kept kosher when she was growing up and she’d been shielded from all that kind of full funkiness of different varieties of cheeses. Her husband though didn’t grow up keeping kosher and he loved all those crazy cheese flavors. So they found an upscale kosher restaurant, they were going out to dinner and she was super excited in particular to try blue cheese. They had a cheese plate for the appetizer. She picked it up, she gave it a try, and she promptly spit it out. She says it’s now an ongoing joke but still, 10 years later, she doesn’t eat blue cheese.

TWILLEY: You know, it is an acquired taste. I hated it as a kid.

GRABER: I did too and now I love it. But, anyway, let’s get back to Europe where all those cheeses on Alana’s cheese plate, that’s likely where they were developed. First, those folks from the Fertile Crescent spread out, so now they’re lactose tolerant. They’re moving to Europe and what they find there is the perfect environment for cheese making, or I guess I should say the perfect environments. Take Emmental, since you mentioned it earlier, that’s what some of our listeners may know of as Swiss cheese. It’s a little harder, it’s kind of rubbery, and it has those characteristic holes.

TWILLEY: And it has this awesome, nutty flavor.

GRABER: Yeah, and what’s interesting is, Paul explained this to me, that unique style of cheese developed in the Alps for very specific reasons. The first thing to know is that they’re far from the ocean and they have almost no salt, and salt is crucial to cheese making.

KINDSTEDT: These cheeses as a practical matter had to be big. It’s much easier to transport under difficult conditions like going down the mountain and then eventually going across valleys and mountain passes to distant markets. Much easier to transport a few large cheeses rather than many small cheeses. So there’s pressure on the cheesemakers to make bigger cheeses.

GRABER: You know, it’s funny, the limitations of the mountain actually make it hard to make cheese. There’s the salt thing and there’s the fact that Alpine milk typically has lower levels of lactic acid bacteria. And like Paul says, practically they had to make larger cheeses. It was a challenge to squeeze out enough of the whey to come up with a good, dry long lasting cheese. So cheese makers in the region came up with some clever workarounds. They invented new curd cutting tools. They cooked the cheese at higher temperatures. They even built cheese presses to squeeze out the whey. And so all of those techniques, they end up inadvertently favoring a particular bacteria, it’s called propionibacteria. And they are the ones that produce the carbon dioxide that creates those holes as well that nutty flavor.

TWILLEY: And then meanwhile in northwestern France, you’re not on a mountain. It’s cooler, it’s more humid. There’s plenty of salt, so you get a completely different style of cheese that develops in response to those conditions.

KINDSTEDT: That creates a microflora that’s just naturally present in the milk and in the environment that the cheese makers were surrounded by and had to deal with. And so when you look at the basic technology of white mold cheese, Camembert, Brie, or a washed rind cheeses, a smear ripened cheese like a real Muenster, Limburger or the very strong pungent yellowish, orangish cheeses.

TWILLEY: That sounds like another cheese we tasted with Heather actually, Saint-Nectaire.

PAXSON: This a very pungent cheese. It’s a raw milk cheese. It’s French. It’s a washed rind cheese, so, as it’s aging, it is rubbed. The outside of it is rubbed with a brine solution that contains a lot of salt, but it’s also microbially rich. Brevibacterium linens are added to it, that creates that orange color on it.

GRABER: Linens like the—

PAXSON: B. linens, that’s the name of the bacteria.

GRABER: …Oh okay. Mmmm. It’s really earthy.

TWILLEY: Yeah, barnyard, in a really good way.

GRABER: Exactly. In a really good way. I’m a big fan of barnyard… cheeses.

PAXSON: Yep, and that’s in part from being made from raw milk as well. There’s a lot going on in that cheese. 10 to the 10 microorganisms.

GRABER: In each bite. That is a crazy idea.

TWILLEY: 10 to the 10, that is 10 billion microbes per bite. That’s more microbes than there are people on earth.

PAXSON: But they’re smaller.

GRABER: The microbes are smaller than people?

PAXSON: Yeah.

GRABER: And we can eat them?

PAXSON: Yes we can. We do all the time whether we know it or not.

GRABER: And we’re back to microbes again. We haven’t brought them up for a little while but we couldn’t stay away forever. Everything seems to lead back to microbes here at Gastropod.

TWILLEY: While we were making this episode, I met a guy who loves microbes even more than we do. He literally has fungal crushes. That sounds disgusting. It’s not.

GRABER: It does sound a little gross.

TWILLEY: His name is Ben Wolfe and he’s a scientist who’s just started his own cheese microbiology lab at Tufts University. I visited with him and we spent an hour just literally gazing at Petri dishes filled with cheese microbes. They look like photographs of galaxies and star systems, like all these swirls of pink and yellow, and tiny pin pricks of white, and puff balls of gray, unbelievable.

BEN WOLFE: That’s great.

TWILLEY: These are pretty.

WOLFE: Yeah. So this plate is where we’re starting to explore the natural history of some of the fungi that grow on certain cheeses. So on this column right here, well actually all the way over here we have the mold, Scopulariopsosis. Which is just a wonderful name for a mold. It’s very Mary Poppinsesque.

TWILLEY: So we’re going to come back to Ben and his lab full of stinky, fuzzy, Mary Poppins like molds and yeasts and bacteria later on in the show. But I wanted to introduce him now because the science of microbes actually has a lot to do with this idea of terroir. So Paul was talking about the idea that cheeses are kind of an expression of the place where they were developed. Those Swiss holey cheeses or the French washed rind cheeses. But as we just heard, and as we’ll dive into more with Ben later, it really all has to do with the microbes.

GRABER: And you know Paul and I had another kind of interesting conversation about this topic. The flavor and texture of cheese is an expression of place, yeah, or maybe place-based microbes. But today it’s actually a cultural and political issue. It’s about what we call the cheese.

MID-ROLL

KINDSTEDT: The plethora of cheeses that developed all over Europe because of these micro-environments and the unique conditions, those cheeses over centuries were given names often directly attached to the place that they originated. So that the name of the cheese, and the place, and the development of the cheese are intertwined in the minds of Europeans. And that concept of what the French call terroir, that the place and the environment shapes the people and their practices. That in turn shape the products that they produce, like cheeses. That those cheeses, those products are unique. They cannot be duplicated anywhere else in the world because you don’t have that combination of unique characteristics. That the terroir is unique and therefore the cheese is unique. And the name that has been given to that cheese over long periods of time is unique and cannot be separated from the place and the cheese.

GRABER: Paul said that’s the European idea anyway. And now there’s this whole legal structure in place. It’s called protected designation of origin or PDO. It started in France as a way to protect the names of wines from certain regions, like, for instance, champagne can only come from the Champagne region of France. And now it’s a whole European Union program. It applies to cheese, and even tomatoes, and lentils, but here’s the problem.

KINDSTEDT: Of course Europeans didn’t stay in Europe. They moved and emigrated all over the world and of course America became a magnet for many of the immigrants who left Europe and they brought with them their traditional cheese making.

TWILLEY: So all of those immigrants started making Cheddar, and Asiago, and Brie, and Gruyère in the United States exactly the same way they would have back at home in England, and Italy, and France, and Switzerland, wherever. And so they used the same names. You have a situation where people in Vermont are making cheddar in the traditional way, but they’re doing it thousands of miles from the village of Cheddar in Somerset. And sure, cheddar cheese originally developed because of the environment and the conditions in Somerset. But it’s still the same cheese when you make it the same way in Vermont, right?

GRABER: This whole issue is actually part of ongoing highly sensitive trade discussions. Today those PDO names are only restrictive in Europe and some cheeses are just considered generic categories like mozzarella, but Europe wants the names to be restricted around the world. That is part of these trade arguments. There’s a great example in Paul’s book, “If the European Union gets its way, all American cheddars would have to be renamed,” and he says, “Maybe a cheese in Vermont would be called something like Vermont Delight.”

TWILLEY: So this is where we get back to microbes and Ben. So a lot of the flavor of cheese, not the ricotta style ones, but the rennet, coagulated, aged ones like Saint-Nectaire, the flavor is coming from a whole community of microbes. Some are in the curd and lots, lots more on the outside, on the rind. And each different community of microbes is basically what gives each type of cheese its particular flavor and texture.

GRABER: Like the Swiss cheese and that Propionibacteria.

TWILLEY: Precisely. And as it turns out a lot of what cheese makers are doing with all their caves, and their washes, and their brining. What they’re actually doing is setting up the conditions for that particular ecosystem of microbes to develop the right way to make the cheese taste like itself. So Ben spends all day, every day looking at these cheese rinds.

WOLFE: In many ways rind is the structure that people use historically in cheese making as a way to help preserve the cheese. So you would make cheese through fermentation and then you needed some surface, something to grow or exist on the outside to keep it from being damaged and to make it easy to transport. So people just let these rinds develop and they found that was a steadfast way to do it.

TWILLEY: In a sort of carpet-like structure almost, right?

WOLFE: We call them biofilms. We call them this biofilm because it’s a layer, it’s a surface, it’s a structure that comes together almost like a small city of microbes, but they glue themselves together. They produce substances that allow them to colonize that surface and stick themselves together. So, yeah, a carpet is a great way of describing it.

TWILLEY: So, in July 2014, he wrote a paper with a colleague, Rachel Dutton at Harvard. They surveyed 137 different cheeses from all over Europe and the United States. And they wanted to see what microbes were where.

WOLFE: The idea for all this work came from Rachel Dutton. So she started this lab at Harvard. And what we wanted to do is go out and understand, what is the diversity of microbes on cheese rinds? It hadn’t been done before in large part because people had been studying their cheeses individually. So a producer in Northern Italy, a producer in the middle of France would work with a scientist to culture the microbes that were growing on their cheese and they would identify things and have a list, but they wouldn’t ever do this in a large, systematic, thorough way. And they also never used the approaches that we use, which were DNA sequencing approaches. So we went out, just like people sequence the DNA at crime scenes or sequence the DNA living inside of your gut. We decided to do that for cheese using the same exact techniques. And we did it at a much larger scale. Instead of doing a few cheeses, we did 137 different cheeses made in Europe and in North America. So we can, in one broad brushstroke, understand the diversity of microbes that’s out there.

TWILLEY: Once Ben and Rachel had all their samples together, they took them back to the lab and they scraped off a little bit of the rind of each one. And then they extracted the DNA.

WOLFE: And then once we have that DNA, we can sequence it using all these great new DNA sequencers that people have developed for the Human Microbiome Project or the Human Genome Project to then decode all the different critters that are there. So what we found is that what the cheese makers are doing, they’re creating environments, particular environments with certain moistures, or certain acidities, or certain salt concentrations. And if they do that, they’re selecting from essentially a global pool of microbes. So either microbes that are coming in on the sea salt, microbes that are in the raw milk that they’re using to make their cheeses, or microbes that they even buy as cultures. And if they create the right environment, essentially if they build it, the microbes will come. You end up selecting for this very particular type of microbe, microbial community. You can make a cheese in California, you can make a very similar cheese in Vermont and try to make that same cheese in France and they’ll have almost the exact composition of microbes in the community.

GRABER: Wait a second, so does that mean that this whole PDO thing that Paul and I were talking about is total bullshit? Or maybe not exactly bullshit but just historical and a political thing and not a difference that’s actually based on science? I mean, if they’re making it the same way, and it has the same microbes that give the cheese the same flavors—

TWILLEY: Hold up, hold up. I asked Ben if he had killed this whole idea of terroir and he said, not necessarily.

WOLFE: So, at this broad scale, we can see that the communities look similar, but we’re talking about walking into essentially an oak forest. If you walk into an oak forest in California, you walk into an oak forest in Vermont, and you walk into an oak forest in France, they would look kind of similar. They would have oak trees, there’s probably some rodents running around in each of those eating the acorns, there’s probably some herbaceous plants in the understory. But if you look more carefully you’ll notice that the species of oaks are different, you’ll notice that the rodents are different. So when you walk around in those forests you’ll notice that there are some subtle nuances that reflect that particular place. And that’s what we weren’t able to capture in our study. So we weren’t capturing strain level variation.

TWILLEY: After Ben and Rachel did this study which seemed to show that the microbes are basically the same in a Vermont cheddar or an English cheddar, he wanted to go back and see if his suspicions were correct. Do different strains of the same species behave differently? So, I mean if a Vermont microbe and an English microbe, even if they are the same species, are they different enough to give a different flavor, to give a taste that somehow reflects place?

GRABER: And so, has he done that study? What has he found?

TWILLEY: It’s happening right now. This, dear listeners, is the most cutting edge breaking news in cheese science.

GRABER: Only from Gastropod.

TWILLEY: Right now in a very smelly lab at Tufts University, Ben is studying exactly this. What he did he got cheeses from nine different places, Oregon, Maine, France, Spain, so on, and isolated the same species of bacteria from each. And then he tried to reconstruct the rinds using strains from different places.

GRABER: Got it. So based on this study design, the idea is that, if the strain doesn’t matter, then he should be able to build an Oregon cheese rind using the exact same species as they would normally in Oregon, but using one that just happens to come from Spain, right?

TWILLEY: Right. Exactly. It’s like this cheese is Lego approach. Except for, here’s the thing, it’s not. Ben is finding that even though the microbes he’s using are from the same species, these different strains from different places do not act the same way at all. The rinds he is recreating in the lab look different, they smell different, and they taste different.

GRABER: So basically there is actually a microbial terroir.

TWILLEY: Exactly. And his next step is to figure out why.

GRABER: Shh, don’t tell the Europeans. Europeans who are listening, pretend you just didn’t hear that. I do not want to call my cheese Vermont Delight.

TWILLEY: Of course. Part of the issue is that Europeans are snobby about American cheese. Because when they think of cheese in America, they are picturing something really, really bad.

GRABER: Here am I… opening up this Velveeta.

TWILLEY: Do we have to? They won’t know.

PAXSON: Velveeta is a cheese that’s made from the little bits and pieces of natural cheese that are industrially made that are sort of waste product, byproduct and then they get melted down, coagulants are added to it, fillers are added to it, coloring is added to it and the slurry, this cheese slurry that does have some natural cheese in there somewhere, is melted and molded in blocks.

GRABER: I love this image of this huge cheese slurry with all these bits of leftover cheeses.

PAXSON: But there is some real cheese in there somewhere.

[CLIP: Singer singing from old Velveeta commercial]

GRABER: Nicky, is your American orange or yellow?

TWILLEY: Orange.

GRABER: Mine is kind of a pale yellow deli American cheese.

TWILLEY: Oh yeah, no, mine is definitely on the orange side. Which I think is right, Heather? Is that annatto, that’s not from the cheese itself, that’s a coloring like a vegetable dye that’s added?

PAXSON: That’s right. The orange color comes from annatto which is a… or the annatto seed. Which is a plant.

TWILLEY: That’s not part of the flavor. That’s just for color?

PAXSON: So it’s interesting. That goes back to… well, if you think of American cheddars, right? Think of a New York State cheddar and a Wisconsin cheddar, right? This is one of our most durable cheese traditions, that on the East Coast cheddar is not colored. It’s yellow. And in Wisconsin it’s colored orange with the annatto. And that goes back to the 19th century. And the cheeses were… the cheese makers initially colored their cheeses to hide evidence of seasonal variation. Which is kind of ironic considering how beloved seasonal variation is these days with artisanal cheese, and it’s often upheld in terms of terroir and so forth. But in the 19th century, when cheese making moved from farmhouses to artisan factory production and they were pulling milk from multiple farms and distributing it to a wider network because the cheese was being traded in greater distances they were trying to standardize the product. And one way of standardizing the product was to color the milk so that the spring milk and the winter milk and the summer milk which had different degrees of beta carotene and other natural colors based on what the animals were eating, whether they were out on fresh grass, or eating dried hay, that you couldn’t tell the difference by looking at the cheese, what season the milk was from. And that just became tradition to keep the orange color in Wisconsin.

TWILLEY: Wow, I had no idea. And so that’s now why we have orange Velveeta and orange American cheese.

PAXSON: That’s right, because orange came to designate quality cheese.

TWILLEY: I talked to Paul about the origins of the first factory cheeses. And just like Heather’s saying, that orange means better quality, strangely it’s the same thing with factory cheese. They were trying to optimize cheese.

KINDSTEDT: Yeah, well, it really goes back to the scientific revolution, the Enlightenment, in the 1700s, when science began to come into its own, in the application of science to practical industries like agriculture. In England, where this really started, the sort of the gentleman scientist, the aristocratic folks who had time on their hands, and had land, and had an interest in agriculture, began to really try and systematize the cheese making process. Which up to that point had been very secretive and sort of a very much an art carried on by the women cheesemakers, the dairy maids and dairy mistresses who handed down that secret knowledge generation to generation. That had been going on for 1500 years.

TWILLEY: And then in the U.S., you get the supersizing of cheeses. There are bigger vats and machines. People move west and there’s more land and that means there’s more milk. Everything gets bigger and, in some ways, actually it gets even better.

KINDSTEDT: In the early years, the 1850s, the 1860s, one of the great advantages of the factory was that it actually improved quality, at least from the buyer’s standpoint. It was easier to control a system in a factory with one set of conditions and one head cheese maker instead of the same amount of cheese being produced at five or 10 different farms, each with a different set of conditions. So from a quality standpoint, if you read period literature, it was actually viewed—the factory was viewed as a great step forward in quality.

[CLIP: Archival TV]

TV ANNOUNCER: And now here’s an idea for quick and festive appetizers. Cut your favorite kinds of Kraft deluxe slices in quarters. These rich-tasting cheese squares fit perfectly on shredded wheat crackers. And we’re decorating them with cocktail onions, sliced olives, and anchovy curls to add a gay note to our tempting cheese nibblers.

TWILLEY: You know, what is so interesting is that in some ways the American slice, that iconic Kraft single, that represents the logic of cheese just taken to its ultimate extreme.

GRABER: I don’t think I like the sound of that.

TWILLEY: Well, no, I mean, I agree, not in terms of taste. But, if you think about it, right, the point of cheese was to make milk portable and long lasting. And James Kraft’s innovation was to realize that if you melted and boiled up cheddar for 15 minutes, and then reformed it into these blocks and slices, you made it last even longer, and so that it won’t melt unless you want it to. It’s even longer lasting and more portable in other words, just like cheese is supposed to be.

GRABER: But then you just killed all the microbes that gave it all that flavor. And it’s so standardized that, I don’t know, today it kind of tastes like nothing. It’s just like fat and salt. Although you know, as Heather pointed out to us, that’s kind of the point. You don’t eat it by itself, you put it on sandwiches.

TWILLEY: For decades this kind of block cheese ruled America. And, in a way, it still does. I mean, if you go by sheer volume, think of all the deli sandwiches, and the burgers, and the nachos, and pizza cheese.

GRABER: But thank the cheese gods that traditional diversity of microbially rich, and flavorful, and distinctive cheeses—that never died out in Europe. And again, thank you cheese gods that tradition got rediscovered here in the US in the 1970s and 80s.

KINDSTEDT: That’s a whole new and somewhat unexpected development towards the end of the 20th century that just has blossomed and created a whole second track or tier of cheese making that really hearkens back to an earlier time. But at the same time that has really benefited from and taken advantage of some of the science and understanding to bring to the table of traditional cheese making. But to do so in a way that really can be controlled, in the sense that it’s much easier to produce really great consistent quality traditional cheese. So the modern artisanal cheese movement is really both the old and the new combined, the best of both worlds.

TWILLEY: In a way, cheese is also part of this much larger story about food and hygiene in the 20th century. At the start of the 20th century you have Louis Pasteur, and you have germ theory and we start trying to make our food system hygienic and scientific. And we spend most of the 20th century just getting rid of the microbes.

GRABER: And, as usual, we went too far. But more recently there is a growing awareness that not all microbes are bad.

WOLFE: So generally we think of molds and bacteria as bad things. They wreak havoc, they grow on our toes, they destroy our bread, they make people sick, they can do that. And so we often have regarded the microbial world as this pest, as this bad thing. But in fact when you look at a wheel of Camembert, when you taste and experience a wheel of Camembert, that’s microbes doing that. Making that thing delicious.

TWILLEY: And then what Ben is trying to do is understand how—how those microbes interact to make flavor.

GRABER: Plus of course, now we know that eating microbes in our food is actually good for us.

TWILLEY: Absolutely, which makes cheese a health food in my book.

GRABER: I like that idea.

TWILLEY: And it might surprise our listeners, but studying cheese is actually also, it’s the perfect model for studying microbes in other systems.

WOLFE: So there’s a big interest right now in understanding how communities of microbes assemble. Just like putting a car together, there’s certain principles for how you put the pieces of a car together. There’s a certain order to how you do it. There’s certain things that need to fit together at the right place and the right time. And we think that also happens in microbial communities. We think that’s happening in soils, out in the ocean, in our own bodies. But we don’t understand what those principles of community assembly are. In large part because most microbial communities are so complex—there’s thousands of species living together. You can’t grow most of them. So what cheese offers is the ability to develop very basic, essentially design principles of how these things come together and do what they do. So we can now dissect them in the lab, they’re very simple. We can grow all of them. Put them back together and learn those principles in the process.

GRABER: How does Ben study microbial relationships in cheese? Does he just stick chunks of cheddar under a microscope?

TWILLEY: Kind of, actually. What he does is makes something called in vitro cheeses, using the super high end cheese curd from Jasper Hill in Vermont. It’s only the best for his bacteria.

WOLFE: Then we get that cheese curd and we freeze dry it and grind it up and then put into agar in a Petri dish. So it looks like a standard Petri dish except it also looks like it has cheese inside of it.

TWILLEY: And then it’s like a cage fight basically. He puts in whichever two fungi or bacteria he wants to see interacting and lets them go for it. So you remember that fungus he described as being like Mary Poppins? Under a microscope it’s got this kind of adorable resemblance to a person holding up a balloon, or an umbrella or something. It’s called Scopulariopsosis.

WOLFE: In the middle we have a fungus, the same one, Scopulariopsis. But it’s growing with another fungus named Chrysosporium, which you could see growing by itself all the way over here. And one thing we’re trying to figure out is, we see Chrysosporium growing on a lot of cheese rinds, a lot of natural rinds really late in succession, really late as the cheese is aging. What we think is potentially happening is it may be a micro-parasite, it may actually eat other fungi. It always grows on the top of other fungi and even when we grow it in the lab it seems to sort of nestle up next to neighboring fungal colonies. So what we’re trying to do is right at that border between the Chrysosporium and the Scopulariopsis we’re trying to look for any kinds of signatures of micro-parasitism. So, looking for where the little fuzzy hyphae of the one mold could be penetrating into the other mold. And it’s essentially sucking away some of the nutrients from the host.

TWILLEY: Basically the Mary Poppins is being eaten alive by a white fluffy thing, or so Ben suspects. So one of the things I actually didn’t realize about cheese before I visited with Ben, is that it is not just one happy family of microbes and you’re done. Instead the aging process is like this intense negotiating table where these different fungi and bacteria interact in succession. One may take over from the other, one may set the stage for the other to colonize. And that whole progression over time is what makes the flavor.

GRABER: But I have a question. In the example you gave, there are only two microbes interacting. And aren’t there… I don’t even know how many, but aren’t there a lot of different types of microbes that may be interacting at any one time?

TWILLEY: Exactly, dozens and dozens on every cheese. But you have to start somewhere, Cynthia. I mean we just don’t know the rules for how those microbes interact with each other. We don’t even know how they know that the other guys are even there. So Ben is going one relationship at a time to figure out the ground rules and build up a picture of how the ecosystem works from there.

GRABER: But we shouldn’t make it sound like he doesn’t know anything yet. I love that when you told me that he’s become something of a cheese doctor for artisanal cheese makers.

WOLFE: There isn’t a great resource out there for people to understand when their products don’t go in the right direction that they want them to, so what we’ve done is developed some of the knowledge, gone out and just sequenced what’s out there and we understand the diversity of microbes you expect to find. And we can then provide this knowledge to help cheese makers understand when things don’t go right, what can they do when they have an invasive blue mold. What is it? Where it’s potentially coming from?

TWILLEY: It’s funny, he gets sent franken-cheeses in the mail all the time. He just emailed me a photo of a bright purple rind on a cheese, totally terrifying. He’s managed to identify the two bacteria that are interacting to make that color and help the cheese maker to tone it down.

GRABER: And strangely, one of our listeners sent us a photo of just such a franken-cheese. It’s a shot Ida Divine took in France. She called herself “Moldy in Avignon” in the email. She was pretty turned off by these bizarre oozing brown cheeses she saw in the market. Here’s her theory, she had three ideas: One was that you could buy them to infect your own milk to make cheese, or two she thought maybe you could mix them in with other cheeses for an extra strong cheesy flavor, or here’s number three, her last one, she thought maybe the cheese-monger was just fucking with the buyers.

TWILLEY: I was leaning to option three there. But I sent the photo to Ben, our cheese doctor extraordinaire.

GRABER: And…

TWILLEY: He said that he too has seen equally disgusting cheeses from France. They were so brown and dusty he said, that he thought they were bread, or bagels or something. But he asked and they are in fact intended to be eaten, although not by him. He didn’t try them despite being a microbe lover.

GRABER: A little too much even for Ben.

TWILLEY: I think you have to be born French. So the cool thing is that all of this research is helping cheese makers improve their product and it’s helping microbiologists understand how microbial ecology works. And that is great, but it is also generating new ideas for the future of cheese. After all, there are a lot of other microbes out there that make tasty foods and don’t currently get used in cheese making.

TWILLEY: I mean, I know the primary goal of your research is to understand the microbe interactions and less what the flavor implications might be or even the human help implications, but are we talking about like a miso-flavored cheese here?

WOLFE: Absolutely, the end goal could be that. But along the way we’re going to learn a lot of really cool basic microbiology and we could learn more about the evolution of these microbes and hopefully they’ll produce a new flavored cheese.

TWILLEY: Like miso-flavored cheese?

WOLFE: So these Zygosaccharomyces rouxii grow really abundantly in soy sauce fermentations and miso fermentations, and produce that caramel-y, that classic sort of dark, rich flavor of those foods, and we’re trying to understand if we can get that to jump over the cheese, yeah.

TWILLEY: And my mouth is watering now.

GRABER: That sounds amazing. Those are two things I am completely obsessed with.

TWILLEY: Form an orderly queue, Cynthia. I am first. We thought we had everything figured out. At least when it comes to cheese. And then we heard from Doug in Perth.

DOUG: Loving the show. The only cheese story I have relates to butter. I maintain butter is effectively cheese with a low melting point, so it’s okay to eat it in a similar way. My 15 month old daughter agrees, she’s a demon for butter and cheese. Which leaves me to wonder, how is cheese defined and does butter really count? Is there a gray area?

GRABER: Back to Heather, we put this question to her. We talked to her about it when we were trying to figure out what cheese actually was and she was clear, butter is not cheese.

TWILLEY: Thank god.

GRABER: First because it’s all fat. It’s all cream. It’s not made of milk. And second because it’s not coagulated.

PAXSON: That process is probably what’s really central to what makes cheese, cheese. It can happen in many different ways but it’s that separation of curds from whey. And that doesn’t happen with butter.

TWILLEY: Don’t let that stop you though, Doug. Butter is good for you again these days, I hear. But have it with some cheese.

GRABER: And in fact we have combined our experts to arrive at the ultimate cheese plate.

TWILLEY: For people listening at home, if they want to put together a cheese plate that shows interesting microbial associations and communities and then show off to their friends about their newfound knowledge, what would be on this cheese plate?

WOLFE: So I think many people break down the world of cheese by milk type and that is not the way to go if you’re trying to impress your friends about microbial diversity. You should go with rind type. So the three main types of rinds that we talk about in our paper, and I like to think about are: natural rind cheeses, washed rind cheeses, and bloomy rind cheeses. So an example of a bloomy rind cheese would be something like Camembert, very classic, those white, fluffy, delicious cheeses that are very creamy, often quite young, and those are very manicured lawns of microbes. So those have been heavily inoculated and they have this very controlled garden of microbes on them. The washed rind cheeses are those sort of funkier, stinkier, cheeses that are washed repeatedly with some kind of brine solution, and those are more yeasty, they have a lot of bacterial diversity in them. The bacteria are producing a lot of these flavor compounds that we smell and taste and those are more like a very disturbed sort of like the ocean coast, where the water is coming in and repeatedly disturbing that ecosystem and selecting for microbes that can tolerate those disturbances. And so you’ll get a lot of unique microbes that can only deal with a heavily disturbed environment.

TWILLEY: So that’s like the Saint-Nectaire we tried with Heather.

GRABER: She also recommended Twig Farm which is a Vermont cheese. And Taleggio is a classic commonly available washed rind cheese.

WOLFE: And the natural rind cheeses are essentially like an old growth forest. It’s been nature that’s just run its own course. The cheese maker doesn’t intervene very much and you’ll get a lot of these really craggly old molds and yeasts and bacteria that are sort of this very old and very mature type of ecosystem at a microbial scale. And I love those kinds of cheeses because they look like lichen-covered rock, they’re really beautiful.

TWILLEY: A lot of clothbound cheddars are natural rind cheese, and if you’re up for the challenge and think you could handle it, a traditional stilton is also a natural rind cheese.

GRABER: So we have got your next cheese board settled. You could pull out some ricotta too or maybe some chevre to represent that older style of acid-heat coagulated cheese. You know, the one from 9,000 years ago. And we’re not going to stop you from putting out some Velveeta too, but I can’t say I recommend it.

[CLIP: Song from old Velveeta ad]

TASHA: My name’s Tasha, I’m a listener from the Boston area. I’m obsessed with Gastropod. Well, when I found out you guys were doing an episode on cheese I got really excited. Cheese is probably my favorite food. I eat it on almost everything. I pretty much eat it every day. I think I have to say that my favorite kinds of cheese—the first one, I don’t even know what the name of it is but it’s like an Arabic braided string cheese. The flavor is just amazing. And then my other favorite kind of cheese is São Jorge cheese. It’s from Portugal. When I was a kid my dad used to love it, but I hated it because I always called it smelly feet cheese. Smells pretty nasty but it tastes heavenly. That’s my little bit about cheese. I love it, it’s the bomb. Cheese is the best thing ever. Thanks.

[CLIP: Old jingle about cheese]

TWILLEY: And that is it for this episode. The future of cheese, I think, it’s golden.

GRABER: And the future of your cheese plate, that’s even better. A huge thanks to our guests, Paul Kindstedt at the University of Vermont, he wrote a book called Cheese and Culture. And thanks to Heather Paxson, MIT anthropologist, she has a book called The Life of Cheese, thanks for tasting all those great cheeses with us.

TWILLEY: And thanks also to Benjamin Wolfe at Tufts University. We have lots of his amazingly beautiful cheese microbe photos online at gastropod.com. Not kidding, they look like far away galaxies. We’ve also got links to the paper he published with Rachel Dutton on cheese rind microbiology.

GRABER: And thanks to you our listeners for sharing so many awesome cheese stories with us.

TWILLEY: As always basically we have all sorts of good stuff online. Photos, videos, links and stories we couldn’t fit in the episode. Visit us there at gastropod.com, where you can also sign up for our emails, binge listen to old episodes, and get in touch with us yourselves.

GRABER: Thanks for listening.

TWILLEY: ‘Til next time.