- Here's a Serving of Science challenge.

What do grape juice, walnuts, Parmesan cheese, mushrooms, and anchovies have in common?

I'll give you a sec.

(Jeopardy game show theme music) It's our fifth taste, and it's called umami.

Our four basic tastes include sweet, sour, bitter, and salty.

But umami is the most complex and what we associate with a savory experience that can be difficult to describe.

Think of many soups or seared meats.

I'm Sheril Kirschenbaum, and on this episode of Serving Up Science, we're going to explore everything umami while making the ultimate flavor-packed umami pizza.

Umami is a term combines the Japanese characters for delicious and taste, and the story of its discovery begins all the way in Japan.

In the early 1900s, a University of Tokyo scientist named Kikunae Ikeda was thinking about the taste of kombu dashi, which is a kind of seaweed broth.

The story goes that Ikeda started pondering whether the savoriness of the dish was a biologically determined taste for, well, something he couldn't quite pin down.

He was determined to figure out what that something actually was, which involved chopping and sampling dried seaweed.

(seaweed crunches in teeth) Mm, seaweed.

And that's when he discovered the savory taste was more than a taste altogether.

It's a sensation linked to the salts of glutamate, which is a type of amino acid that we encounter frequently, like in monosodium glutamate, also known as MSG.

Hmm, MSG itself is pretty delicious.

At first, you get a hint of a salty taste, and then it blossoms into something bigger and familiar but hard to pin down.

In our meals, it's not quite its own flavor but a special mmph that enriches others.

But wait a sec.

(record scratching) Isn't MSG bad for us?

No.

It just gets a bad rap, which is based more on rumor than science.

And, in fact, despite so many reports over the years of MSG being associated with headaches, sluggishness, and more, scientists have never been able to replicate those symptoms in the lab.

People who think they are sensitive to MSG may be legitimately reacting to something else in the food that they're eating but probably not the MSG itself.

Or, in many cases, symptoms might be the placebo effect when diners anticipate a dish will cause them not to feel well.

Regardless, scientists say MSG is A-OK, so you've got one less thing to worry about.

Good to know since it naturally occurs in so many of the foods we eat.

(seaweed crunches in teeth) Delicious and nutritious.

At this point, you might be picturing miso soups and soy sauce, but umami is in a lot of the cuisines we love all around the world.

Think Parmesan cheese, mushrooms, grape juice, cured ham, walnuts, mackerel, dried tomatoes, a lot of the foods that you probably have in your kitchen right now.

Did you know it's even in one of the most frequently consumed favorites in the US?

Pizza, (people cheering) which has cheese and tomatoes packed with glutamates.

So let's make the ultimate umami pizza.

I went ahead and rolled out the crust into a pan, and my oven is ready to go at 425 degrees Fahrenheit.

A key step a lot of people miss is giving the crust a few minutes in the oven first.

Now onto step two.

I have my cheese, my tomatoes, and other toppings like mushrooms and cured ham.

So you wanna begin by ladling or drizzling or however you prefer onto the crust as evenly as possible.

Aside from burning the pie, there's really no wrong way to put your toppings on the pizza, so just have fun with it.

Generously add as much mozzarella as you think your guests will enjoy.

I think we like a lot of mozzarella in this house and on the floor.

And the Parmesan, which is pretty much straight umami.

I'm gonna be adding mushrooms to this pie and some cured ham, just always good on pizza.

And when you're satisfied, you wanna add some color and umami goodness with a dollop of basil pesto on top.

And now into the oven for eight to 10 minutes.

Now that the pizza's cooking, let's explore the science of umami or at least what we know.

Umami involves both tastes and aromas, but scientists still don't understand exactly how and why.

It's a lot less clear cut than our four basic tastes, where we can see an underlying evolutionary reason for each.

Sugars are essential because they help us think and run and move and carry out all sorts of important behaviors, like eating, so we crave a sweet sugary taste.

Salt is required by our bodies but not in large quantities, so a small amount tastes good while a pile of salt just doesn't.

Both bitterness and sourness provide us with important clues about what we might consume.

These tastes can indicate when something is toxic or has begun to rot.

- Eww!

So in this way, sweet, salty, bitter, and sour can all provide important information linked to human survival, but umami?

That's still a mystery, albeit a delicious one.

Let me check on the pizza.

Looks good.

(up-tempo, lively music) (crunch) Mm, that's good.

The pesto really complements the rest of this, and I love the Parmesan cheese; it's delicious.

But now let's check in with some pizza experts to rate our umami pie.

(upbeat drum music) All right, it's time for our experts to weigh in on what they think of umami pizza.

(crunching) - Okay, I took a bite.

- All right, what did you think?

- Mm.

- I like how it tastes like greasy and cheesy.

- (chuckles) Greasy and cheesy.

Those are two of my favorite things, too.

- I like the cheese.

- Ah, I like the cheese, too.

That's Parmesan and mozzarella together.

Have you ever heard of MSG?

- Yeah.

- What is it?

- I don't know.

- Wanna taste a teeny tiny taste?

(suspenseful instrumental music) - It tastes like metal.

- Oh.

(Summer laughs) - Tastes salty.

(Summer laughs) - Tastes even stronger.

All right, everyone, on a scale of one to 10, what do you give umami pizza?

- A nine.

- All right, high five!

(hands clap each other) - Nine.

- Woo!

My pizza is popular.

- A nine.

- Ooh, nine across the board.

There's umami in seaweed.

Would you put any seaweed on your pizza?

- Yeah.

(crunching) - Looks like it's a hit, definitely something I'll be making again.