Pod Insights Short Wave Eating Breakfast? You Can Thank Fermentation About this episode In this episode, you're invited to the fermentation party! Join us as we learn about the funk-filled process behind making sauerkraut, sourdough and sour beer. Plus, no fermentation episode is complete without a lil history of our boy, yeast.
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Transcript Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
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0:17 Speaker 00 You're listening to Short Wave from NPR.
0:22 Regina Barber? Hey, Short Wavers. It's Regina Barber. And we're starting today's episode with breakfast. Because regardless of what you had for breakfast today, chances are at least part of it was made by fermentation. Yogurt and granola, fermentation. Eggs with cheese, fermentation. Bread, fermentation. It's even key in coffee.
0:42 Speaker 02 When a coffee bean is harvested, you know, in the jungles of Costa Rica or Colombia, or wherever it might be, those berries, which look like little tiny cherries or almost like crab apples, they get hauled into baskets or trucks and then like thrown onto the ground. And there's either like dry or wet fermentation. But in both cases, just whatever endemic microbes are in the jungle, on the fruit, start to acidify and metabolize all of the fruit flesh. And all those metabolize, all the acids that are produced, all the organic molecules seep into the actual coffee bean itself and change its flavor.
1:20 Regina Barber? This is David Silber, chef, reality TV show host, and former director of the fermentation lab at the world famous Danish restaurant, Noma. And he told me, if fermentation wasn't part of my coffee, it wouldn't even be good.
1:35 Speaker 02 If you took a fresh coffee bean and like completely stripped it of the fruit and dried it immediately and then went through the same roasting process, you would end up with the most like flat, cardboardy, acrid coffee compared to what happens post-fermentation. So fermentation is incredibly important step in coffee production.
1:55 Regina Barber? To make it taste delicious.
1:56 Speaker 02 Yeah.
1:57 Regina Barber? Yeah.
1:57 Speaker 02 Complex.
1:59 Regina Barber? OK, I'm convinced fermentation is important. But what exactly is it?
2:04 Speaker 02 Fermentation is the transformation of one food into another with the help of microbes.
2:09 Regina Barber? To me, that transformation kind of sounds like magic, like you're a wizard and you wave your wand and you turn cucumbers into pickles. But David says it's also kind of like being a bouncer at a nightclub.
2:23 Speaker 02 You, as the fermenter, take the role of the bouncer. You have a velvet rope at your disposal. You stand at the door. And a great ferment is the club inside where it's full of beautiful people, making great conversations, sipping on champagne, and it's a fantastic party. And it's your job at the door to turn away all the bad actors, all the people that are going to go inside and start a fight, you know, just ruin the vibe. You just want to let in the good microbes.
2:51 Regina Barber? So today on the show, welcome to the hottest spot around: club fermentation. We're talking microbes, we're talking acids, we're talking sauerkraut, sourdough, and sour beer. You're listening to Short Wave, the science podcast from NPR.
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4:44 Regina Barber? Okay, so David, let's just start with the beginning, your beginning. When was the very first time you fermented anything?
4:51 Speaker 02 Yeah, so I was in grade school and I was like at home alone in the morning. I was just eating Honey Nut Cheerios like any other North American kid, watching Transformers on Fox Kids.
5:02 Regina Barber? Yeah.
5:03 Speaker 02 And I don't finish my breakfast. I just throw the bowl up on the counter and then like jet off to school. And this is like end of the school year, it's summer, it's hot in our little cramped apartment in Toronto. And I come back to my mom who's already like setting up for dinner. And then she's like, "Clean up after yourself. Your breakfast is still on the counter." And then I go like, "Mmm, sorry, Mom, pick up the bowl." And the milk is set. It's like jelly. And I'm like, "Mom, what has happened?" And she's like, "You made yogurt. Now, please clean it up. We have, we have stuff to do." And I was like, "Hmm, how can I make yogurt? That is something you buy."
5:36 Regina Barber? Yeah.
5:36 Speaker 02 I can't just like leave the house one day and make Lego when I come back. That's something you buy from a toy store. Yogurt is something you buy from the grocery store. But yeah, I was, I was doing research and I was like, "Oh, wait. All these microbes that live in your mouth are the same microbes that people have used for fermentation for thousands of years." Like the, the reason you have to brush your teeth is because lactic acid bacteria eat all the food that doesn't make it down your esophagus and turn all those scraps into lactic acid, which then rots your enamel and corrodes.
6:09 Regina Barber? I love that.
6:10 Speaker 02 And that is, that is the same action.
6:12 Regina Barber? Right, you're, you're putting those microbes back into the, the milk that's in your cereal.
6:16 Speaker 02 Exactly. And if you're lucky, they're there in the right amounts to do what they do in yogurt. And acidify the milk, coagulate the milk proteins and make this gel.
6:30 Regina Barber? So when you're fermenting something, let's start at the beginning. Like, what do you need to start this fermentation process?
6:36 Speaker 02 You need food. You need food that you would want to eat, that hopefully also the microbes will want to eat.
6:43 Speaker 02 So to start any fermentation process, you need the food you're looking to ferment. Then you need to find the microbes. There's a couple of ways of going about that. One, they're everywhere. That's good. It's good that they are everywhere. They're on you, they're on our skin, they are high up in the troposphere. You know, floating on moats of dust. There are microbes that have been found in like gold mines in South Africa. And they're probably also on the food itself, whether that's flour, whether that's a cabbage. On any given food, they are there as a minority population with a lot of other bacteria, soil bacteria, microbes, you know, microbes that might be found in feces or manure from the actual field itself.
7:26 Speaker 02 And it's your job to suppress those microbes immediately by using things like oxygen, or an absence of oxygen, more specifically, or salt, to make sure that they are tamped down and you give center stage to those lactic acid bacteria.
7:44 Regina Barber? Right, right. And so what do they do, like those lactic acid bacteria?
7:48 Speaker 02 They will start to release enzymes into their environment that will break up the carbohydrates in the plant cells themselves and allow them to digest these sugars. Carbohydrates and starch and lots of plant fibers are just stitched together chains of simple sugar molecules, like glucose. And so in the great tree of life, lots of organisms have devised enzymes that snip those daisy chains into their constituent molecules. Then they can grab an easily handable portion of chemical energy in the form of sugar, eat it, and through the process of fermentation, which, going back to the textbook microbiology
8:31 Speaker 02 definition, is the metabolism in the absence of oxygen of a sugar molecule into either ethanol or lactic acid.
8:41 Regina Barber? Okay, so just to review, the microbes take the sugar like from the carbs and starches and whatever food they're given and they start to break it down. They start to eat it, right? And that process of microbes eating sugars and turning it into energy, that's fermentation.
8:55 Speaker 02 Yeah. And then when it harvests the chemical energy, energy for its own purposes, what's left over is lactic acid.
9:02 Regina Barber? Okay. That's the byproduct.
9:04 Speaker 02 That's the byproducts. That's like microbial poop, basically.
9:07 Regina Barber? I like that.
9:08 Speaker 02 The good thing is that humans seem to like the flavor of lactic acid. And even when a food source gets pretty acidic, and we're talking about below 4.5 on the pH scale, like, we find it pretty palatable. And it's something that we enjoy eating. So they're in the Venn diagram of foods that microbes like and foods that humans like, there's a lot of overlap there. And when they get the party down in our food supply, we seem to like what they do. And so this is, in every way, shape and form, a symbiotic relationship.
9:44 Regina Barber? So we're talking, I'm thinking of like, you know, like you said, sauerkraut, pickles, like kimchi, those are all like, like you said, lacto fermentation. What about like alcohol, like beer, sake, wine, mead? Like, how is that process different from what we just said?
10:01 Speaker 02 Um, that-
10:02 Regina Barber? And how is it the same?
10:03 Speaker 02 Yeah. It is, it is, it is different, but it is the same. Um, we're gonna, we're gonna go back down the phylogenetic tree of life to the origin of eukaryotes. So there's phylomantis fungi floating in the ocean. Uh, and then, uh, one of these multicellular organisms was like, eh, I'm gonna revert back to being a unicellular, just, just me and my kids floating as little dots in the sea, microbes. It's kind of like whales going back into the ocean.
10:33 Regina Barber? Wow.
10:34 Speaker 02 Fungi evolved from single-celled organisms and yeast.
10:38 Speaker 02 Nothing truly devolves, but yeast went back from being multicellular organisms to adopting a single cell lifestyle once again, which is interesting.
10:45 Regina Barber? That is fascinating.
10:46 Speaker 02 Yeast are, yeast are cool critters. They are eukaryotes like us, which means they have a cell nucleus. There are thousands of varieties and all yeast really means is single celled fungi. So we think of yeast as like, oh, yeast is the thing that is in bread, but there are like thousands and thousands of varieties of yeast, so many different types and clades. And so they do a lot of the same things. If we're baking sourdough bread, they use the action of some of those same lactobacillus bacteria that we just talked about. They'll take sugar and they will produce ethanol, yes, but they'll also produce carbon dioxide.
11:23 Regina Barber? Right.
11:23 Speaker 02 And that carbon dioxide production is what helps to make these little pockets of, you know, gas formation inside of a bread dough.
11:33 Regina Barber? Yeah. I've never, I've never actually linked bread visually with pockets and beer of carbon dioxide and like alcohol, like that is, it's the first time that's ever in my mind connected. I, I, I'm fascinated and like people have been fermenting foods for millennia, right? What, what's the benefit of fermenting like foods? Like, why do we think people have been doing this for so long across so many cultures?
12:03 Speaker 02 Historically, you can't keep microbes out of your food if you try. This is, this is something we can't forget, right?
12:11 Regina Barber? It's just by accident.
12:13 Speaker 02 Like, like just, just the history of humanity. You want to talk like plagues and infestations and disease, like humans have had a rough go of trying to keep microbes out of ourselves, right? Our food was no exception. So the sorts of kind of culinary tricks that probably primarily many women working in kitchens, many grandmothers and mothers and sisters and daughters tinkering, being like, oh, this worked and it worked really well. I should keep doing that because this has lasted or it tastes good or it keeps well.
12:53 Speaker 02 These kind of happy accidents have like accrued and accumulated over thousands of generations.
13:01 Speaker 02 To be these entrenched kind of
13:04 Speaker 02 cultural bodies of knowledge that we understand as fermentation. It really is this like falling together. It really is this kind of, it is this kind of beautiful symbiosis. It's like, how do symbioses arise in nature in any way, shape or form? It's an accident that works so well that the two parties become bound to each other. Whether those are like cleaning fish on a whale shark or, you know, oxpeckers on a hippo. Like, it works to the benefit of both parties. And that's exactly what has happened with humans and the microbes that we use in fermented foods.
13:36 Regina Barber? David, thank you so much for talking to us about fermentation. I learned so much. I'm glad that you love it. I can tell you love it.
13:45 Speaker 02 It's fun, and I love teaching other people about it.
13:52 Regina Barber? This episode was produced by Hannah Chin and edited by our showrunner, Rebecca Ramirez. Tyler Jones checked the facts. Maggie Luthar was the audio engineer. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thanks for listening to Short Wave from NPR.
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