- They are bulbous, arguably ugly and wildly expensive.

Their striking earthy scent and taste have made them culinary celebrities all around the world.

I'm Sheril Kirschenbaum and on this episode of Serving Up Science, we're talking about the fungus among us, truffles.

First of all, truffles aren't mushrooms.

- You know what truffles are?

- They're underground mushrooms.

- Truffles have mycelium or a kind of microscopic level thread that extends out to several hundred meters and connects to the roots of the trees.

That way, the truffles have a cozy place to grow.

They transport water and nutrients to the trees and get sugars in return.

Even though they grow underground, you might say that truffles are having a moment in the sun given their popularity in steak, pasta, chicken, potatoes, soup, salads, popcorn, mayonnaise, pretty much everything you can possibly imagine.

But odds are that you're not experiencing them in their full glory.

Most restaurants use truffle flavored oil, not the real thing.

Our passion for these morsels, not morels, dates back centuries to when botanical handbooks claimed they could be used as aphrodisiac or traditional medicines.

This may be because truffles contain what we call bioactive polyphenolic compounds which are antioxidants that benefit our health.

Today, I'm making an omelet with real truffle Gouda.

We looked for real truffle oil, but couldn't find it.

So I brought in an expert to tell you the trouble with truffles.

Joining me in the kitchen today is mycologist and overall fun guy, Greg Bonito.

- Hi, Sheril, it's great to be here.

I brought you a selection of truffles from around the world.

There's hundreds of different species of truffles and about a dozen or more that have some commercial value.

- What's the one that looks like a white strawberry?

- This is scleroderma.

- Isn't that a skin condition?

- Sclero means hard and derma is skin.

And so the skin of this truffle, the top is very hard.

That's how it gets its name.

Well, we call these false truffles.

We often free on the surface, so the soil, you can see there's a little moss there.

So it fruits around pine and sometimes hardwood trees, but it's not a real truffle and this one could make your stomach sick if you ate it.

- So don't pick up random fruiting bodies on the ground because they might not be so good for you in the long term.

So with the variety we have here, are any of them edible?

- There are three edible truffles here.

There's the black truffle from China.

There's tuber borchii, that's from Italy.

This is one of my favorite.

This is an Oregon black truffle called leucangium and it often has a pineapple-y kind of fruity aroma.

- And what about this little squishy one right there?

- This squishy one, it's a rubber truffle.

- Oh, a decoy.

- It's a fake out and you'll know that it's not real cause it doesn't really have an aroma.

- Well, speaking of edibles, not the psychedelic kind.

- Man this is crazy.

I hope I didn't brain my damage.

- We are gonna make an omelet today.

So I am gonna start by adding some butter to this pan.

And while I get this going, would you please pass me the scrambled egg over there to your right?

For this omelet, we're gonna be adding truffled Gouda cheese.

- Oh, that sounds good.

- You might notice the eggs are a little bit lumpy.

That's my secret ingredient.

Touch of cottage cheese makes them extra fluffy when they cook up in the pan.

I don't know if I believe that was a genuine mm, but I'll take it.

- Well, that'll be good for the truffles because truffles need some sort of lipid or cream or something like that to take up the aroma so I think your cottage cheese trick will do just fine.

- I didn't use truffle oil to make the omelet with truffles mainly cause I couldn't find any with real truffle in them.

- There's a lot of synthetic or fake truffle products out there.

It's fairly easy to synthesize some of the compounds that give the big peaks of the aroma.

And if you see aroma, then that means it has some of these synthetic products.

- Well, I have an omelet here for you with some real truffle cheese in it if you might like to try some.

- Oh, looks truffle-icious.

- Well, thank you so much for joining me in the kitchen.

You go enjoy that truffled egg and I'm gonna be telling you all a little bit more about truffle science.

Once on earth, hundreds of scent molecules waft off fresh truffles and every single one has its own unique odor influenced by weather, its host tree species and the bacteria living in and on the truffle.

In fact, truffle scientists couldn't decide if the odor was produced by microbes or the fungi itself, but they now believe it is the interaction of both.

Whatever it is that makes the selectable magic happen, it's sadly short lived.

A truffle scent molecules diffuse away within five to 10 days and the fungus starts to rot.

To extend a truffle's lifetime, sellers must boil or freeze the fungal flesh, but that destroys the texture and undermines the odor.

Although many of the most fragrant truffles species grow in Italy, France and Spain, different species of this fungi can be unearthed all around the world and even where they grow, finding them isn't exactly easy.

Truffle hunting requires a four-legged companion who has been trained to locate their pungent smell from underground.

Pigs are famous for this and indeed they are very good truffle hunters, but they're also extremely good truffle eaters.

So today truffle hunters tend to travel with specially trained dogs instead.

- What is that?

Is that a truffle?

These dogs just founded truffle.

- Not surprisingly, supply does not near meet demand and then there's climate change.

As temperatures rise and conditions become drier, many species of wild truffles we love are expected to become even rarer.

Less rain in productive regions means less water for the trees and in the soil where truffles grow.

More surface evaporation in the heat will also offer less water to tree roots and the fruiting bodies of fungi themselves.

So what's a truffle lover to do?

For now, truffle researchers are hard at work learning more about the hidden lives of truffles and their enigmatic aromas.

Scientists have been exploring the unique relationships between these fungi and the trees they cohabitate with in hope of eventually figuring out how to grow them in more places.

Their attempts haven't exactly worked out so well yet.

Cultivating truffles seems well complicated, but enjoying them isn't.

(upbeat music) but enjoying them isn't so are you a truffle super fan or have the truffle products you've enjoyed been real truffles at all?

Tell us in the comments and let us know what surprises you most about truffles.

(upbeat music)