Jane: This is But Why: A Podcast for Curious Kids from Vermont
Public. I'm Jane Lindholm. On this show, we take questions
from curious kids just like you, and we find answers. We humans
eat a lot of food. Three meals a day, plus snacks. That really
adds up. You know, food is essential for keeping us alive,
but it's way more than that. Food makes us feel pleasure...
or sometimes revulsion, when you're grossed out by something
on your plate or in your mouth. Food helps us bond with friends
and family. It's a way we learn about and share our culture. So
it stands to reason that you have a lot of questions about
food, and it's been a while since we did an episode all
about food. So today we're going to talk with a guy who thinks
about food and writes about food and talks about food and makes
food all the time.
Kenji López-Alt: I am Kenji López-Alt. I'm the author of The
Food Lab and The Wok as well as the children's book Every Night
is Pizza Night, and I host a YouTube show called Kenji's
Cooking Show.
Jane: Kenji also helps us figure out how to make good food.
Kenji López-Alt: I write recipes for home cooks, so I try and
help people make food at home more easily or better. Yeah, I
try and make people feel more comfortable in the kitchen.
Jane: I think kids might be surprised to know that that can
be a whole job.
Kenji López-Alt: Yeah, it is a whole job. Yeah, well, because
nobody's born knowing how to cook, and a lot of people are
lucky enough that they learn, you know, how to cook from their
parents, or perhaps, you know, someone else in their household
growing up. But a lot of people don't do that, and they find
themselves out in the world having to feed themselves or
feed their friends and family, and they don't really know how
to do it, you know, they're just kind of plopped in there, and
they've got to figure it out on their own. So my job is kind of
to guide people, to help them do that with some amount of
confidence. And my goal has always been to think about
myself when I was first learning how to cook and to, you know,
sort of to write to myself as if I was... the books and the
material that I wish I had when I was learning how to cook.
Jane: Kenji says you can get a lot of insight into people by
learning about what they eat.
Kenji López-Alt: Humans are social animals, and we like to
interact with other humans and learn from other humans and feel
a bond with other humans and a connection with them. And food
is one of the ways that everybody in the world does
that, you know. So food becomes part of our social and cultural
identity. So you can, I find that my favorite way to travel
around and learn about people is by going around and eating the
food and experiencing food in the way that people do, because
it tells you a lot about how they think about the world. It
tells you a lot about the climate they live in. It tells
you a lot about sort of what sort of family structures they
might have, what customs they might have. So, you know, food
is a thing that we do, most of us do multiple times a day,
every day. And most of us do it in a somewhat social way. We
feed each other. We nurture each other. You know, food, for me,
is also a way of showing care and love for other people.
Jane: You don't have to travel to faraway places to start to
understand different food cultures. Look around you when
you're visiting a friend next time, do your friends' meals
look different from yours? Does their family have rituals or
customs when they all sit down to eat that are different from
how your family eats a meal? What kinds of spices do they
have out on the counter? Are they the same as the spices at
your house? What do those spices smell like? Familiar? Or do they
tickle your nose in new and interesting ways? And if you
spend time in a school cafeteria, what kinds of meals
do they serve at your school? It's probably a mix of
ingredients and flavors that are familiar to you with some new
things thrown in now and then to get you to try something
different. But if you went to school somewhere else, those
cozy comfort foods might not be the same.
Rowan: Hi, I'm Rowan. I'm four years old, and I'm from Rhode
Island. Why do some people like other foods that some don't, but
they're all really good.
Maya: Hi, my name is Maya. I'm six years old, and they live in
Kalamazoo, Michigan. Why does food taste different to
different people?
Nouri: My name is Nouri. I'm six years old. I'm from Western New
York. Why does one person like one food while another person
doesn't?
Elena: My name is Elena. I am seven years old. I live in Mesa,
Arizona. Why do different people like different foods?
Kenji López-Alt: When you think about taste, you think you've
learned that you have taste buds on your tongue, and those are
your taste receptors, and those are the things that tell you
what something tastes like, but food is actually... the
sensation of taste is a lot more complicated than that. Not only
do we have receptors on our tongues, but when we're eating,
we're all we also have receptors in our nose. We're taking in
smells. We also have visual receptors. We're looking at the
food, we're hearing it crunch. We're feeling the texture of it
in our mouth. So there's this whole host of sensory data that
the sensors in our body are connecting. So you know, your
tongue doesn't have a brain. All it is is, is a tool. It's a
piece of sensory equipment. And so what the tongue does is it
detects certain things, and then it sends those signals to the
brain. And it's not until all that information from from our
tongue, our nose, our eyes, our ears, you know, the sensation of
touch in our mouth, all of those signals get sent to our brain,
and then our brain does some very, very complicated computing
on it, you know. So there's you're taking that information
and sending it through through the sort of thought matrix in
our brain. And then we finally say to ourselves, okay, this
tastes good, or this doesn't taste good. And so even if our
tongues might be detecting the same things, or our noses might
be detecting the same things, our brains are never the same
because we all have different experiences. Or we might, you
might even be in a different mood from one day to the next.
Jane: Wait. Our mood can impact how we taste food? Kenji says
yes, and he's even got an example.
Kenji López-Alt: Last summer, I did this experiment on an
auditorium with a thousand people, where we had every
person taste a piece of chocolate while a violinist was
playing some really upbeat, happy music. And then we had
them taste another piece of chocolate when a cellist was
playing a sort of somber piece. And then afterwards, we asked
people which, you know, which chocolate tasted sweeter, which
chocolate tasted more bitter? And they almost all said that
the one that was being eaten while the violinist played the
happy piece tasted sweeter and better. The thing is, we didn't
tell the audience what we were doing. You know, the music was
just kind of incidental in the background. And we told the
audience initially that it was two different pieces of
chocolate, but in fact, they were the exact same piece of
chocolate, and so even, even just the different stimulation
they were getting from their ears made the chocolate taste
different. And you know... You know this, because if you've
ever been to the beach, you know, you might want a glass of
really nice cold lemonade on the beach because you're feeling
hot, you're feeling like nice summery weather, but you don't
want a glass of cold lemonade when you're coming in from the
snow on a cold winter day, in the same way that you don't want
to drink hot chocolate while you're on the beach, you know?
So depending on a whole host of different things our upbringing,
you know, like the food that you that you grew up with, is going
to produce certain memories in you, some of them more
pleasurable than others. And not everybody had the same
upbringing. So things that your mother made that you especially
loved when you were a child, those are going to give you a
taste memory that's going to give you a sort of sense of
satisfaction and make you like the food more.
Eden: Hi. My name is Eden. I'm five years old. I live in
Ottawa, Canada. Why are some foods spicy and some aren't?
Nathan: Hello, my name is Nathan. I live in Seattle, and
I'm six years old. My question is, why do some people like
spicy stuff?
Jafar: Hello. My name is Jafar, and I'm five years old, and I
live in Seattle, Washington. Why do I find stuff spicy, and my
parents don't find some stuff spicy?
Kenji López-Alt: The chemical that produces the sensation of
spiciness, of heat, it's a chemical called capsaicin that's
produced naturally in a lot of pepper varieties, and we can
actually measure exactly how much Capsaicin is in a certain
pepper. So we can say definitively, you know, this
pepper is spicier than that one. What we can't say, however, is
what does spicy mean to one person versus the next? In the
same way that, you know, some person, somebody might find it,
you know, when they stub their toe, they might find that to be
extremely painful. And someone else might just say, oh, it's
just a stubbed toe, you know. And so, so people have different
levels of tolerance for pain in the same way that they have
different tolerance levels for heat, which makes sense, because
the spiciness that we detect when we're eating spicy foods is
literally the same as we detect when we're when we're feeling a
burn, you know, a physical burn from a fire or a physical
injury. There are receptors on our tongues called TRPV1
receptors, and those are the receptors that sense heat and
pain. And capsaicin actually binds to that receptor and
stimulates it, so we get the sensation of burning and hurting
even though we aren't, so it mimics heat.
Jane: Wow, I didn't realize my brain was interpreting spicy
food the same way it interprets something that's really hot.
Kenji López-Alt: The other thing that spicy foods can do is,
because our body thinks it's heating up or it's getting hurt,
it'll actually cause some of the same reactions that we get when
we start to heat up, you know? So our blood flow will increase,
we'll have a boost of serotonin. Serotonin is a, it's a mood
changing chemical that our body produces, that when, when we
feel pain, our body produces serotonin to sort of help us
fight through that pain, and it also gives us a sort of
pleasurable experience, which is why some people really love
eating spicy foods, because they love that, that rush of
adrenaline and serotonin that they get. It can also cause your
body to sweat because you think you're getting hot. So you'll
find that oftentimes spicy foods are eaten in hotter climates.
Partly it's because that's where peppers tend to grow, but it's
also theorized that it's because spicy foods help people deal
with the heat. It helps our bodies produce more sweat, and
when you sweat, body cools down. So eating spicy foods can
actually help you tolerate heat a little bit better. But as far
as you know, perceiving different levels of spiciness, a
lot of it just has to do with building up tolerance. You know,
in the same way that you can exercise your muscles so that
they get stronger at riding a bicycle, or you can, you can
work through, you know, I when I worked in kitchens, when I first
started being on your feet, you know, 10 to 10 to 14 hours a
day, it causes a lot of pain in your feet, but eventually you
get used to it. So in that same way, the more spicy foods you
eat, and the sort of the earlier in your life you're introduced
to them, the more heat tolerance you'll get in, the less hot some
certain foods will taste to you compared to someone who doesn't
Jane: So that helps answer your question, Jafar, about why your
parents are able to eat much spicier food than you are
without feeling like it's too spicy, or maybe even spicy at
all. The more spicy food you eat over time, the more you'll get
used to it. But Kenji also says it's totally fine not to eat or
like spicy foods. You do you!
Jack: My name is Jack, and I am five years old. I live in
Okinawa, Japan. Why are some foods spicy in your mouth and
some foods spicy in your nose?
Jane: I love this question because it's so true! When I eat
really spicy Thai food, I taste it in my throat and my mouth and
my lips. But when I have wasabi with my sushi, the wasabi feels
like it's shooting right up my nose if I eat too much of it.
Kenji López-Alt: Yeah, well, so, so spiciness is almost always
associated with capsaicin. There is a certain, when we when we
eat things like, say, mustard or wasabi, the types of things that
kind of go up the back of our nose and really give us that
tingling in our nose. That is, that's, I suppose that's also
spiciness. It is a different kind of spiciness, so that
that's produced by a chemical called allyl, isothiocyanate,
Jane: We looked it up. It's called allyl isothiocyanate.
iso... isothiocyanate. I can't, I can't, I can't remember, off
the top of my head, it's one it was. It's a big word, AITC.
AITC is how it's abbreviated.
Kenji López-Alt: So AITC, similarly, is going to bind to
those same receptors that trigger the sensation of heat
and pain. However, it's a much more volatile molecule. So
capsaicin is a relatively large, heavy molecule that is oil,
salt, fat soluble, and will sort of sit on our tongue and coat
our tongues, you know, whereas AITC is a volatile molecule,
which means that it's much more prone to sort of jumping off
into the air. It's very light, and it's prone to jumping up
into the air. And so when you eat a food that's heavy in AITC,
rather than attacking our tongues directly, it's more
likely that it's going to jump up into our noses, or go up
through the back of our throats, up into our noses, where then it
will bind to those same receptors in our nose. So
instead of feeling the pain on your tongue, you feel it in your
nose. On the other hand, because it's so volatile, it also
generally doesn't last as long, so capsaicin can stick to your
mouth and make you feel the burn for, you know, 10, 20, maybe
even 30 minutes before, before you stop feeling it, whereas
AITC generally lasts more, like, you know, 30 seconds to a
minute, you get this really intense feeling that then very
quickly dissipates as well.
Jane: What is it that people like about spicy food? People
who don't like spicy food are like, it's awful, and people who
like it, it's like, I like it, it enhances the flavor. But Why
do we like that sensation of something burning our throats or
our nose?
Kenji López-Alt: Spicy foods do enhance other flavors because it
they make us more alert. You know, they make us sort of more
attuned to our senses. They give us that sort of fight or flight
response that our body, you know, when our body senses
there's some kind of danger, something's going wrong, all our
senses get heightened. And so you do, you know, when you're
when your body is getting triggered by these spicy foods,
you're getting a very mild form of that response. And so you do
end up sort of noticing other flavors more. So some people
say, especially with Thai food. You know, if you've ever eaten a
Thai dish, or like a central Thai dish, that without any
spice to it, it can taste sort of almost like overwhelmingly
sweet. Where that, where the where the sugar, or some of the
or maybe some of the acidity, really blocks out some of the
other the flavors of the actual ingredients that you're eating,
you know, the vegetables or the meat, and then when you balance
it with that spiciness, those sort of more subtle flavors come
forward. It tames the overt sweetness, attain some of those
other sensations that you get on your tongue, and allows your
body to really pick up the aromas and really attunes it to
the aromas.
Jane: Coming up, a flavor as divisive as spiciness. We'll
talk about pickles.
This is But Why: A Podcast for Curious Kids. I'm Jane Lindholm.
Today, we're talking about food with chef and food writer Kenji
López-Alt. We're exploring flavors we like and flavors we
don't like. And some of the sensations we get from food,
like spiciness in our throat and nose. Do you like spicy food? Do
you put hot sauce on your scrambled eggs or pepper flakes
on your pizza? I do, but I used to eat a lot more spicy food
than I do now, so I feel like I've lost some of my spice
tolerance. Let's talk about another thing some people love,
and some people absolutely do not like even a little bit:
pickles. Are you a pickle person? Let's crunch into it.
Bridget: My name is Bridget. I'm five years old. I'm from
Greeley, Ontario, and my question is, when was the first
pickle made?
Jane: When was the first pickle made? Do you know?
Kenji López-Alt: That would be almost impossible to tell,
because likely pickles were an accident, in the same way that
likely most fermented foods were an accident. You know, pickles,
the way you make a pickle, the simplest way you make a pickles,
you take a vegetable or meat, you can, you know, you can cure
meat, which is essentially pickling for meat, and you pack
it with some salt. Pretty early on, humans discovered that salt
preserves food, that things that were stored near salt wouldn't
go bad as quickly, and when you leave some vegetables sitting by
salt for a long time, is going to naturally pickle. What the
salt does is it prevents the growth of things like mold and
certain bacteria that are harmful, but it allows for the
growth, the sort of, the controlled growth of bacteria
that can actually be helpful, and, you know, yeast and
bacteria and things that, things that are going to produce the
sort of sour pickley flavors without actually harming the
nutritional value of the food.
Eli: Hi, my name is Eli, and I am eight years old, and I live
in Idaho. Why are pickles crunchy from cucumbers?
Kenji López-Alt: Vegetables... You know, all plants are made up
of cells that have cell walls, and they're kind of stuck
together by a glue, a carbohydrate glue called pectin.
And so when, when a vegetable goes limp, the reason it goes
limp and soft is because it's lost a lot of its moisture, or
it could be because the cell walls start to break down, and
so the cells themselves are starting to get, starting to get
soft. So a crunchy vegetable is crunchy because it's packed with
water and because its cells are really nice and intact. What
happens when you pickle things is that you're packing them in
what's called a hypertonic solution of salt solution. So
it's something that is very salty, and it's salty enough
that it actually draws moisture out from inside of the
vegetables. And so your vegetables are going to end up
naturally getting a little bit softer. In addition to that, the
cell walls can start to break down, the pectin can start to
break down. And so what you need to do is introduce some elements
to make sure that pectin doesn't break down as much and that the
cell walls don't break down as much. Typically, natural ways of
doing it are things called tannins, which are ingredient,
antioxidants that you find in things like tea leaves. So some
people recommend putting a, you know, like a half teaspoon of
tea leaves into your pickle jar if you want to keep the pickle
fresh. The flowers of a cucumber can also contain tannin, so you
might add some cucumber flowers directly into the jar with it.
Typically, though, when you're when you're talking about
commercial pickles, or even home pickling, we add a chemical
called calcium chloride. And calcium chloride is a, it's a,
it's an edible chemical. But that that is also going to sort
of help those, keep those cells plump and sort of firmly
connected to each other, and that's why, that's why pickles
stay crunchy. If you don't add any of those things, you will,
in fact, get soft cucumber pickles.
Jane: Salt is a big factor in making pickles, and some of you
have questions about salt.
Zachary: Hi, my name is Zachary. I'm from Miami, Florida, and I
am eight years old. Why is sea salt called sea salt? I thought
all salt was from the sea.
Kenji López-Alt: At some point, all salt was in the sea. That is
true. What we call sea salt is sea salt that we specifically
today, get from the ocean. So all salt was in the sea. But we
have things called salt mines, you know. So you go, you can go
into mountain ranges and dig and find big deposits of salt under
the ground. And so a lot of salt comes from mines. However, at
some point in the, in ancient history, that salt was all part
of an ocean. So a lot of... a lot of our mountain ranges
today, you know, I was, I was just in Utah with my kids in
Moab, which is a desert now, you know, mountainous desert, but at
some point that whole area was underwater, under an ocean. And
so you can find the fossils of sea creatures high up in the
mountains there. And so all that water, as it evaporated, left
large amounts of salt deposited in the earth. And over, over the
millions and millions of years that mountains take to form,
some of that salt ended up sort of underneath rocks, underneath
silt, underneath petrified mud flats, things like that. And so
you end up with with salts that was at some point in the ocean,
but is now in mines. If you go out to say, Yeah, Salt Lake City
in Utah, you know that there's a big Salt Lake out there that is
not part of the ocean, but it's still very salty. And that's all
ancient ocean salt that is now dissolved in a lake. And so what
we refer to as sea salt today is salt that is still in the ocean
today that we are drawing out of the ocean. So typically the way
that we collect harvest sea salt is we very long, flat trenches
around the ocean where sea water collects, and then we allow that
water to evaporate with the sunlight, and so and as the
water evaporates, the salt gets more and more concentrated,
until eventually it can't there's not enough water for the
salt salt to stay dissolved in. And so it forms these crystals.
And depending on sort of the specific mineral content, you
know, salt, all salt is mostly sodium chloride. In fact, all
salt is sodium table salt, the salt that we use to season our
food is sodium chloride. But depending on where we harvested
our salt from, they could have other trace elements and
minerals in there that are going to slightly affect the flavor,
though not too much. But what it can really affect is sort of the
shape of the salt crystal that forms. And so you might see salt
crystals that form into these sort of perfect pyramids. You
might see salt crystals that form into sort of cube or
gemstone, like sort of moist, moist piles, you know, or the
salt that we, that we make commercially, forms into these
tiny, perfect little cubes because we eliminate all of the
all of the material, the minerals and other compounds
that might make a change of shape.
Jane: And it can change the color too, depending on where
it's from.
Kenji López-Alt: Oh, yeah, yeah. So we get, you know, from
Hawaii. You can get black salt from the volcanic, you know,
from the minerals that come out of the black volcanic rock
there. You can get pink sea salt from Hawaii as well, that comes
from the materials in clay, or the pink sea salt from the
Himalayas that comes from the minerals there, you get sel
gris, which is like a gray sea salt from France that forms from
the sort of silty waters in the ocean there. So yeah, depending
on where your salt is from, those minerals can absolutely
change the texture, the color and well, in some ways the
flavor, although really the main flavor changes come from those
textural changes, like a crunchy salty pyramid is going to taste
different from a sprinkle of very fine salt, for example, in
the same way that, say, a ruffled potato chip tastes
different from a flat potato chip.
Sam: Hi, I'm Sam. I'm five years old, and I live in Irvine,
California. Why do we eat different foods for different
meals?
Jane: Why do we eat different foods for different meals? We
have customs where we think of maybe scrambled eggs, for some
people, as only a breakfast food, and it would be weird to
try to eat it for dinner. So why do we have these customs about
when we eat certain foods?
Kenji López-Alt: Well, you know, a lot of that is just purely
cultural and things that have developed within different
cultures over the years. Because in the US, for example, you
might have eggs or something sweet, you know, some sort of
sweet pastry for breakfast. But if you go to Vietnam, you might
be, you might eat a bowl of noodles for breakfast. If you go
to Japan, you're going to, you might eat some grilled salted
salmon and a bowl of rice for breakfast; you go to you go to
France or Italy, and you might eat pastry and a cup of coffee
for breakfast, you know, a slice of bread. So it's not really
true that we eat certain foods. It's only it's depending on
where you are, those foods are going to change. What you can
generally say, though, is that most breakfast foods tend to be
sort of really energy dense, relatively quick foods that can
either be prepared quickly the morning of or can be prepared
the night before, the day before, and that can be sort of
taken on the go, because generally, you know you're
waking up, you don't want to put you don't have five or six hours
to put into your meal, and you need a lot of energy for the
start of your day. And so that's why we tend to see sort of
really fast, easy to cook things like eggs, pastries that could
be made the night before, breads that could be made the day
before, things like that for breakfast.
Danica: Hi, my name is Danica. I'm nine years old. I live in
Atlanta, Georgia. Why do we eat dessert after a meal and not
like before a meal or in the middle of a meal?
Kenji López-Alt: You know dessert was is a concept that
only exists because of we live in a time of great abundance and
excess. You know, we're able to create these sweet, elaborate
concoctions that that when we were evolving, we certainly
couldn't. And so we discovered, okay, sugar tastes good, but you
know what, if you eat too much of it, it can make you sick, can
make you unhealthy. So sugar is, you know, what we call a treat.
And so desserts are generally treats, and so you want to eat
your meal before you eat your treat, so that you don't fill up
your treat and you get the nutrients you need. So I think,
I think it is just a learned behavior that we realized, hey,
we need to get the good stuff before we can get to the fun
stuff.
Jane: Dessert is always a good place to end an episode. But I
want to offer you one more thought before we finish up.
We've had a mixture of science and culture in today's episode,
and that's perfect, because there's a lot of both when we
think about food. But there's something really key that we
haven't talked about that applies to both science and
culture, and that's just how important cooking is to human
evolution. Cooking food transforms some of the chemicals
and structures in the ingredients we eat. It can make
food taste really different, much better, in some cases, than
it was raw. But it also often breaks down the food to make it
easier for our bodies to digest, and it can make food safer by
killing bacteria. Cooking is one of the things that makes humans
unique in the animal kingdom.
Kenji López-Alt: A lot of evolutionary scientists
speculate that one of the biggest advances for humans, as
far as being able to evolve, was the invention of cooking,
because it suddenly meant that we didn't have to spend as much
energy digesting our food. So if you look at most animals, they
actually have a much larger digestive system compared to the
size of their bodies than humans do. So a cow, for example, has
four very large stomachs that takes up a big portion of its
body, and it spends a lot of time eating and digesting its
food. Humans, on the other hand, have a on the other hand, have a
pretty small stomach, and it's because we have evolved to eat
our food cooked, and so we can readily grab the energy from it,
and don't have to spend all of our time cooking. And we can
spend our time doing other fun things. We can do other
productive things and other fun things. We can play, we can run
around, we can build skyscrapers. We can study food
and do science. There's all these other things that you can
start doing once you have time freed up because you're not
spending all of your time looking for and digesting food.
Jane: Wow. Think about that. One of the key things that makes us
human and has given us the ability to use our big brains
for all kinds of things other than just finding and eating
food, is that we learned how to cook. So maybe you'll spend some
time with your adults this year learning some new cooking
skills. What do you want to learn how to make pizza, cake,
Bibimbap, collard greens, masoor daal? Think about what you enjoy
eating and what you think you might enjoy cooking, and then
get some help and learn how to cook it. Then you can
experiment, try new ingredients in that meal, or different
spices: maybe more pepper and less salt, or maybe a little
more milk. Maybe not if you're baking, but if you're cooking, a
different kind of meal. Cooking can be so fun, and you're not
only feeding yourself, but you're showing love to the
people you care about. So on that note, don't forget to
appreciate the people who are cooking and caring for you, too.
That's it for this episode. Thanks so much to Kenji
López-Alt for answering all your great food questions. He's got a
book for kids called Every Night is Pizza Night, and you might
enjoy listening to the Recipe, a podcast for adults. He co hosts
with Deb Perelman. Their most recent episode is all about
burgers. Now, as always, if you have a question about anything,
have an adult record you asking it. You can do it on a
smartphone using an app like voice memos, and then have your
adult email your file to questions@butwhykids.org. We
can't use all of your questions in our episodes, but we listen
to them all, and we love hearing from you. But Why? Is produced
by Melody Bodette, Sarah Baik and me, Jane Lindholm at Vermont
Public and distributed by PRX. Our video producer is Joey
Palumbo, and our theme music is by Luke Reynolds. If you like
our show, please have your adults help you give us a thumbs
up or a review on whatever podcast platform you use to
listen to us. We'll be back in two weeks with an all new
episode. Until then, stay curious.