IRA FLATOW, HOST:
This is SCIENCE FRIDAY. I'm Ira Flatow. Five years ago, my next guest offered us this simple advice on what to eat: Eat food, not too much, mostly plants. The man behind that advice is Michael Pollan, writing in his book "In Defense of Food: An Eater's Manifesto."
Now that Pollan's told us what to eat, he's taking us to the next logical step: how to cook it. His new book is "Cooked: A Natural History of Transformation," a tour of time-tested techniques for preparing food inside and outside the kitchen, from smoking a roast over wood coals to slowly simmering that Sunday ragout, baking sourdough bread, even making your own pickles, a lot of pickling and fermentation in that book. We're going to get into that in our talk with him.
And you know, what you learn from this book is you're not just feeding yourself with all that home-cooked fare. He says there are hundreds of species of bacteria living in your guts. As Pollan writes: We're eating for one, when we need to be eating for, oh, a few trillion. How does what we eat change those communities of microbes, and what is the connection between the health of those bacteria to the overall health of our whole body?
And for all you raw foodies out there, Pollan says our bodies may be specially adapted for cooked food, like it or not, because there's evidence humans have been cooking for nearly a million years, if not longer. Lots of science in this book that may change the way you eat. We won't be taking your calls this hour, but if you want more information about what we're talking about, go to our website at sciencefriday.com.
Let me formally introduce Michael Pollan, author of "Cooked: A Natural History of Transformation" and "The Omnivore's Dilemma," among others. He joins us from WRTI in Philadelphia. Welcome back.
MICHAEL POLLAN: Thank you, Ira, good to be here.
FLATOW: Why a book about cooking? Is it a natural extension of your food interests?
POLLAN: Yeah, it is. I mean, I wasn't expecting to write about cooking, but, you know, I had written one book about the earth end of the food chain, "Omnivore's Dilemma," and how the food is produced from the earth. And then I'd leapt ahead and looked at nutrition science and written a couple books about health, including "In Defense of Food" and "Food Rules."
And I realized I hadn't really paid attention to this middle, where the stuff coming off the farms is transformed into meals. And the more I learned about the whole food chain, the more influential I realized that middle step was, because what happens on the farm is directly influenced by the way we're eating.
If we're eating industrially, if we're letting large corporations, fast food chains, cook our food, we're going to have a huge, industrialized, monoculture agriculture because big likes to buy from big. So I realized wow, how we cook or whether we cook has a huge bearing on what kind of agriculture we're going to have.
FLATOW: You know, and you could have subtitled your book "Back to the Future" because a lot of what you talk about in your book is going back to old ways of preparing food.
POLLAN: Yeah, I'm a little freaked out about how reactionary this book is in some ways. I am - you know, but the more I study food, the more I see that most of the innovations have not been very positive, beginning in about 1880. The long history of cooking, if you go back to the million years ago or two million years ago it may even be, every time we came up with a new technology for processing food, beginning with fire and then pottery that allows us to cook in water over fires, and then bread making, cheese making, all these technologies made food dramatically more nutritious, easier to digest, tastier - and then something happens.
And I date it to about 1880, when food processing takes a fateful wrong turn. And ever since, with the exception of sort of frozen - you know, frozen vegetables and canned vegetables, I can't point to an innovation that has really contributed to our health, perhaps to our convenience but not to our health.
FLATOW: Let's talk about some of these older ideas that are still used today, but not really by Western cultures as much, and for example, fermentation. I'm going to quote from your book: fermentation puts us in touch with the ever-present tug in life, death.
POLLAN: Yeah, well, you know, once you start studying fermentation, you're acutely aware of the fact that everything that lives contains the seeds of its own decomposition and that living on in the same way that on the leaves of a cabbage at any given time are various bacteria species just waiting for a breech in the cell walls to leap in and digest and rot that cabbage, you've got a lot of bacteria on you and in you waiting for the same moment.
And these bacteria are our friends, but when we die, they get - they make quick work of fermenting us. And - but, you know, you go around the world, and every culture has very important ferments. This is a cultural universal, it appears. And there's a good reason for it.
Fermented food, first of all, you know, before refrigeration, that's how you preserved food. I mean, you could dry it, but the big way to preserve especially vegetables that allowed people to get through the whole year was to ferment food: dig pits and bury food and have this kind of controlled rot.
And what happens when you ferment food is that the lactobacillus basically break the sugars down into lactic acid, which is a preservative. And so you acidify the food, and along the way it also gets much more nutritious and much more flavorful. And - but this has just been, you know, a mainstay of civilization right up until refrigeration gave us another way to preserve vegetables.
FLATOW: Now you say it gets more nutritious. Why is that?
POLLAN: Well, when you ferment, and this is true for other kinds of cooking, you're essentially taking digestion out of the body. You're externalizing digestion and starting that process of breakdown outside the body. So you take a very kind of fibrous plant, and you start to ferment it, let's say a cabbage leaf, and the bacteria produce various enzymes that begin to break down the cellulose and the lignin and the other fibers in the plants.
So it's easier to break down for our bodies. We don't have to chew as much, we don't have to, you know, use as much digestive action or acids. So it starts the process of digestion before you've taken a bite.
FLATOW: You talk about whom you call the Johnny Appleseed of fermentation, Sandor Katz.
POLLAN: Oh yeah. Has he been on your show?
FLATOW: Not recently.
POLLAN: Oh, OK. Sander is - he's the guru of vegetable ferments, of all ferments, actually, and he was one of my teachers. And he's a great - you know, I describe him as a pacifist in the world war against bacteria. You know, much of public health, much of science for the last 150 years or so, really since Pasteur, has been obsessed with bacteria as the enemy and that indeed there are pathogens that - pathogenic bacteria that make us sick and cause disease.
But, you know, 99.9 percent of bacteria are benign, and a great number of them are also actually, you know, in a symbiotic relationship with us. They help us, and we need them. We're dependent on them. And they perform various services, ecosystem services for our bodies that are critical.
So when I started fermenting and studying with Sandor, it completely changed my thinking about bacteria because I'd grown up in a household where, you know, my mother would throw out a can of tomatoes if it got a dent, even if that dent came from being dropped, because she was sure it had botulism, and we always heard about trichinosis and lockjaw, and there were all these bacterial hazards lurking in our food.
And now I court the bacteria. So I've gone through this real revolution, and that's because of these fermentos that I hung out with.
FLATOW: Yeah, and you say that we are obsessed with cleanliness. America is just so fearful of bacteria, we don't realize that there are trillions of them living in our bodies and that, as you say, they help us and that bacteria have evolved with us. And in fact one of - someplace in your book you say that 99 percent of the DNA in our bodies are not ours.
POLLAN: Is bacterial, yeah, microbial. Ira, you're only 10 percent human. Isn't that amazing?
POLLAN: And you're 90 percent microbial. And so, you know, these microbiologists who are doing this work now on what's called the microbiome, that's the collective genes of all the microbes in your body, are really encouraging us now to see ourselves not as individuals but as super-organisms.
You know, we're kind of like a coral reef. There's a great many other species occupying us, sharing our bodies, and we need them, and we need to look out for them. And one of the hallmarks of the Western diet, as you alluded to in your intro, is that it's been designed to very effectively feed us, the 10 percent, with these - you know, we process food to make it much more readily absorbable, you know, lots of refined sugars, lots of refined carbohydrates, lots of easily absorbed fats, but very little is left for the large intestine, where the real action is going on, where you have this interior fermentation, if you will, that we're not feeding very well.
And because those guys like different food than you do in some ways. They really like fiber, for example. They love plants. They love a variety of fiber, too. That's a real mistake of I think what we're doing now. We're kind of supplementing everything with fiber, but we're only putting in one or two different kinds of fiber.
And every different microbe probably likes to chomp on a different kind.
FLATOW: I wanted to talk about a couple of new studies that just came out suggesting that red meat and eggs might contribute to heart disease risk, not because of the usual suspects like cholesterol, but because of how the microbes in our guts digest steak and eggs.
POLLAN: Yeah, fascinating work. Basically there are - if you eat a lot of meat or a lot of eggs, you have cultivated a population of certain types of bacteria, and in fact they haven't even identified exactly which they are, that metabolize or basically ferment those foodstuffs. And one of the byproducts of that fermentation are compounds that have been linked with heart disease in both cases.
Why this should be, we don't really understand. Many of the byproducts of this fermentation are very good for you, although I was talking to a biologist the other day who was saying, well, we have to remember these bacteria, some of them are just there, and they're taking advantage of us. And they're - some of these more toxic byproducts really don't affect people until they're past their childbearing age.
Because I was wondering why would we have evolved to have microbes that would do this. And he was pointing out that, well, you know, natural selection doesn't care about you after you've had kids. And in fact one microbiologist, speaking of another species that is implicated in gastric cancers and peptic ulcers, H. pylori, this scientist said, well, maybe it's there to help shuffle us off the stage when our childbearing years are over. I thought that was a rather sobering idea.
FLATOW: That is interesting, talking with Michael Pollan, author of "Cooked: A Natural History of Transformation" on SCIENCE FRIDAY. And we're going to take a short break and be right back with Michael Pollan. Stay with us. We'll be right back after this break.
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FLATOW: I'm Ira Flatow, and you're listening to SCIENCE FRIDAY from NPR.
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FLATOW: This is SCIENCE FRIDAY; I'm Ira Flatow. And we're back with Michael Pollan, author of "The Omnivore's Dilemma" and his new book "Cooked: A Natural History of Transformation." And one of the most fascinating parts - as you know, Michael, from listening to SCIENCE FRIDAY, we love to talk about the biome and the bacteria in the guts and everything that help us.
And is the realization - and you talk about this in your book - that this is like the - to me it's like the undiscovered world under the ocean, we know so little about what's under the water, we know so little about what's inside our guts and how that might be responsible for us being healthy.
POLLAN: Well, you know, we've only just acquired the tools to peer into it. It's only recently that we have powerful enough sequencing machines that you can take a sample of feces or the sweat on your hands or the saliva in your mouth and sequence everything. And this is really only - we've only had this for about 10 years, the ability to do this.
And we also haven't had, though, the intellectual tools, and in that case it was bringing the concepts of ecology to the gut and these bacteria and realizing that there is a system and that it's all working together in a certain way and that the ecosystem has a dynamic to it. And for example once it's organized - and it doesn't happen until you're about three years old, it resists invasion. And that's a very important ecosystem service of the gut is that when you ingest a pathogen, the community, your community, works very hard to keep that pathogen from getting into your bloodstream or otherwise, you know, hanging out too long.
So it is a whole new world, and it's - we're just at the beginning. And the kind of excitement I found talking to these microbiologists - and they're not just microbiologists, by the way, they're ecologists, microbial ecologists now, working in this area, chemists who look at these byproducts of these bugs.
You know, you can feel Nobel Prizes in the air. There is that crackle of excitement that - I mean, you know this from interviewing a lot of scientists - when they're on the trail of really big discoveries. And in this case, they're very big discoveries about human health that are probably not too far away.
FLATOW: This is not something they're teaching in medical school. You know, they are - they started teaching medical students about eating correctly, you know.
FLATOW: I can't imagine they're talking about how keeping your gut healthy is going to make you healthier or leads to good health.
POLLAN: Not yet, not yet, and one of the things that I was very curious about is OK, well, now that we know that this community is very important to our health, what can we do to garden it? You know, how can we cultivate it and make it more healthy? And a lot of the scientists I interview aren't ready to make recommendations, and they're very concerned not to overpromise the way the human genome scientists were promising all sorts of cures that somehow haven't yet materialized.
So they're very cautious. But if you ask them what they've changed in their own life, it's very interesting to heat the kinds of changes they've made in their diet and in their attitude toward things like sanitation. Many of them talk about, well, I make a point to encourage my kid to play outside as much as possible and play in the dirt, expose them to bacteria, just lighten up a little bit on the hygiene routine.
Many of them will say that they're eating much less processed food. And I asked them why that is. And I figured it was all about the lack of fiber in processed food, and that's part of it. But the other is they're very concerned about common food additives that may not - that have never been tested for their impact on the microbes. They've only been tested on their impact on the 10 percent.
And in fact they're worried about some of those chemicals. And they're - you know, these guys are really into eating whole grains and a variety of whole grains. So there are things we can do to start feeding the microbiome. And an important one is fermented foods, and that was...
FLATOW: Let's talk about that, yeah. Tell us what - because you have a very interesting experience that it didn't go well for you at the beginning when you started experimenting yourself fermenting foods.
POLLAN: Yeah, I made a batch of sauerkraut that had a slight overtone of septic, a septic tank.
FLATOW: I hate it when that happens.
POLLAN: At a certain point, and I think I had fermented it a little bit too warm. And I opened it up at one point, and I was like, ooh, this is bad. And I was about to toss it, but before I did, I wrote to Sandor, and - Sandor Katz, and I said should I - am I on the wrong track here?
And he said give it another week. He's so relaxed, I mean, as someone who loves bacteria is likely to be very relaxed about this stuff. And he said sometimes, you know, there's a succession going on, an ecological succession in a sauerkraut or a kimchi or a pickle, and one variety of microbe is kind of proliferating for a little while, poisoning the atmosphere with whatever its byproducts are, acidifying it progressively, and then another one takes over.
And he said you're in the middle of this, and there may be an (unintelligible), you know, basically an intestinal microbe that had gotten in there and is proliferating now, but it'll be succeeded by something else.
So I waited another two weeks, and it was fine. And that stench had gone away, and the climax species of the fermentation ecosystem, which is a lactobacillus plantarum, and you find this in pickles and kimchi and everything, it's the acid-loving oak of the system, and it had finally dominated and stabilized the situation, and I had a very nice sauerkraut except that I then got mold in it.
POLLAN: And it got mushy. And that was another argument for keeping it cool. So it's an interesting kind of cooking because you can't control everything. As one cheese maker said, this is nature imperfectly mastered. The best you can do is kind of guide it down this pathway or that, but you can't call all the shots in a fermentation.
FLATOW: So fermentation is basically cooking without the heat.
POLLAN: Exactly, it is cooking food without any heat whatsoever, and what a miracle that you can do that. I mean, I don't know that people realize just how simple it is, but if you simply dice up a cabbage, salt it, then mix the salt around by hand and bruise the leaves as much as you can, the bacteria lurking on those leaves will get right to work.
The salt will draw the liquid out of the leaves, creating your own brine, and then you put it in a crock, and within 24 hours, it will be bubbling, and you will hear these bubbles of carbon dioxide, which is one of the byproducts of the bacteria, and they will just - their populations will bloom, and they'll get to work on this transformation. It's one of the most magic of all the transformations I learned.
FLATOW: Talking with Michael Pollan, author of "Cooked: A Natural History of Transformation," a really - you always write fascinating books, but as someone who likes to cook myself, I found it's even more fascinating. And as someone who loves cheese of all kinds, your chapter on the Ph.D. cheese nun in there...
POLLAN: Sister Noella.
FLATOW: She was - tell us about her a little bit.
POLLAN: Well, she's an amazing character. She is a nun, and she's in a Benedictine abbey in Connecticut, in Bethlehem, Connecticut. And she learned a few years ago - they had cows there, and they were trying to figure out what to do with the milk. And a cheese maker from France came over and taught them how to make a very traditional French Saint-Nectaire, it's called, from the Auvergne.
And she is making it according to a traditional recipe that would give conniptions to the FDA or any local public health authority.
POLLAN: And the reason for that is she makes it in a wooden barrel with a wooden spoon or ladle to stir it. Now you cannot sterilize wood, and in fact the instructions for this cheese are - and talk about learning to love bacteria - the instructions for washing it out is just rinse it with a little water, no soap, no attempt to disinfect.
The public health department tried to close her down. She appealed to the mother superior, and she got permission to go to the University of Connecticut and become a microbiologist, get her Ph.D. so that she could defend her cheese-making on scientific grounds, which she did as follows. This was - she set up this brilliant experiment.
Most cheese today, all cheese except for hers, I would guess, and maybe in parts of Europe, are made in stainless steel, which we think of as the ultimate in hygienic technology, right, because you can really sterilize it. Well, she got two batches of raw milk from her cows. She put one of them in a stainless steel container, and she put the other in her wooden barrel with the white film.
And she inoculated them deliberately with E. coli, waited a couple hours and then measured the levels. Well, in the stainless steel, E. coli bloomed magnificently, and there was very high, very dangerous levels of E. coli in that milk. In the wooden barrel, the levels were vanishingly small.
And what had happened was that the lactobacillus that lived in the wooden barrel got to work digesting the lactose in the milk, producing lactic acid, and they acidified the milk and killed off the E. coli. So you realize these traditional peasant cheese-makers in France had been practicing a kind of folk microbiology without even knowing it, strictly through trial and error, they had found a system that defended itself against pathogens.
And with this experiment, which she did for the health inspector, they backed off, and she continues to make cheese, or her - the other nuns do. She doesn't actually do it. She's done such damage to the carpal tunnels in her wrists from making cheese all these years that other people are making it. But they're still making cheese in this traditional manner, and it's a wonderful product.
FLATOW: Do they start out with raw milk?
POLLAN: Yes. She - and she feels strongly about that. A lot of cheese makers do. Raw milk, because it has so much bacteria in it, has a lot more flavor too. Every kind of bacteria in raw milk is producing an enzyme that's - that is itself breaking down products in the milk and creating flavor. So most cheese makers will tell you that raw milk cheese, even though a certain risk is attached to it, produces a lot more flavorful cheese.
FLATOW: Talking with Michael Pollan, author of "Cooked." Just a few minutes to go, Michael, but I want to make sure you talk about how you make bread, because the way you get your starter dough going is different than, I'm sure, 99 percent of cooks do.
POLLAN: Well, most people use yeast, and I used to use yeast in the very little - you know, very few times I made bread. But I strongly recommend trying to create your own starter, which is not that hard. Basically, you make a paste of flour and water, and you make it the consistency of, say, pancake batter. And you whip air into it with a fork or whisk, as often as you think of it as you're going through your kitchen, for several days.
Eventually, microbes, both fungi and bacteria, will find their way into this new habitat you've created, and they will colonize it. And it will start bubbling, and you'll realize it's alive. And from that point on, you have a starter that you can have for the rest of your life as long as you feed it. You have to feed it every day, or you can, kind of, put it into suspended animation. Like right now, my starter is in the fridge - in the back of the fridge - till I get home from book tour.
And this - if you make bread with this starter, a couple of tablespoons of that, instead of yeast, the results are astounding. There is just so much more flavor. And if you're making whole-grain bread, it's just incomparable. You can't make good whole-grain bread with yeast. It crumbles in the toaster, and it just has very little character.
So learning this little trick of, you know, using the traditional sourdough starter - I mean, yeast is fine, but it's a monoculture. It's like this thoroughbred microbe that does one thing, which is add air to bread. But all these other, you know, members of that little sourdough community add so much more, not just yeast. There are yeasts in it, but they add a tang to things and a really complicated flavor.
And they break - they even break down the gluten in ways that makes that bread, for people who have trouble with gluten, much easier to digest. The Italians have done interesting studies to show that if you properly ferment a bread with the sourdough, gluten will not be a problem for you.
FLATOW: People should not be fearful of the stuff falling into the dough as it's sitting there?
POLLAN: No, that's bacteria...
POLLAN: ...phobia right there.
FLATOW: Yeah. That's exactly what I'm asking. Yeah.
POLLAN: No. I mean - no. They're not - I've never heard a story of toxins in a sourdough starter. Again, it's an acidic environment.
POLLAN: Lactobacillus are central to that ecosystem, and they protect it. These communities can look out for themselves without a lot of help from us.
FLATOW: And I'm going to - you know, you got me thinking about going back to bread baking again because it was so - such an interesting part of the book.
POLLAN: I got really deep into it, and I'm still doing it. I find it incredibly satisfying, very sensual. At a certain point, I was able to throw away my recipe books and trust my senses in what dough should smell and taste and feel like, and realizing when it was ready. And it's also - it's just alive, you know? And I really - it's sort of like gardening for me. You're in this dialogue with these other species. You just can't see them.
FLATOW: Michael, it's a delightful book, and I want to thank you for - and wish you good luck and thank you for taking time to be with us today.
POLLAN: Always fun, Ira. Thanks a lot.
FLATOW: You're welcome. Michael Pollan, author of "Cooked: A Natural History of Transformation." It's, as I say, it's a wonderful read. You really will enjoy it, and it will change the way you make food and the way you look and eat it. So pick up - I recommend picking up a copy whenever you can. Thanks again, Michael.
POLLAN: Thank you.
FLATOW: I'm Ira Flatow, and this is SCIENCE FRIDAY from NPR.
Michael got us so interested in fermentation we thought we'd offer you some help in trying your hand at fermentation. What better first project than pickles, homemade fermented pickles. Flora Lichtman found a fermentation guru.
FLORA LICHTMAN, BYLINE: I'm talking with professor of food microbiology at the University of Nebraska. This is Bob Hutkins. And would it be fair to call you a pickle expert?
DR. ROBERT HUTKINS: Well, I guess I'm an expert in fermented foods, and a pickle is a fermented food, so I guess that's fair enough.
LICHTMAN: OK. So there are different kinds of pickles, right? Will you break them down for me?
HUTKINS: The pickles that we eat most of the time are actually not fermented. These are just fresh pickles that are packed in a brine. Sometimes they're pasteurized, sometimes they're not. But the pickle that's fermented is the genuine dill pickle that is actually becoming fairly hard to find these days.
LICHTMAN: Is that right?
HUTKINS: So if you live in New York City, you can go on in a deli, and you could find a pickle in a barrel, and that's a fermented pickle. But out here in the Midwest, I actually have a hard time finding pickles to bring into my class to show the student what a true fermented pickle is. I remember from my younger days when I go to the grocery store and find a barrel and use tongs to pull out a fermented pickle, but it's fairly rare these days.
LICHTMAN: Could you walk us through a recipe for a fermented pickle, for someone who wants to try this at home?
HUTKINS: So I have to tell you that I've not done this myself.
HUTKINS: So with that caveat, you know - and, actually, I would probably recommend - there's sources online that you could find to do this. But it's basically about a five percent salt brine, mixed one to one - by weight, one to one, with pickle and cucumbers and some sort of crock device or small barrel. You could even do it in mason jars, and then take a baggy with also some brine in it, and lay that on top of the cucumbers to weigh them down, but the ideas to squeeze out the air to try to create an anaerobic environment as best as you can, and also protect the pickles from the elements.
LICHTMAN: How do you know when they're done?
HUTKINS: You should see some bubbling when the fermentation begins after just a couple of days. And it's safe to taste that brine. And when you taste its tart, I probably give it a week at room temperature, you probably have pickles and very little could go wrong. There's little opportunity for any kind of pathogen to grow in this kind of brine. In fact, I'm not aware of any adverse effect by making these pickles at home, provided that you haven't improperly canned them that would be a different story. And a week of fermentation, you have pickles.
LICHTMAN: Sounds easy. Thanks, Bob Hutkins, for joining me today.
HUTKINS: You're welcome. It was a pleasure to talk with you today.
FLATOW: We'll be right back.
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