[Narrator] The debut of vegan cheese

didn't inspire confidence.

This is weird.

The mouth feel is like a Play-Doughy mouth feel.

[Narrator] But in the years since,

vegan cheese has gone from this.

Oh, yeah, it really tastes like cheese.

No, it doesn't.

[Narrator] To a grocery store staple.

[Rhett] I wouldn't know this wasn't cheese.

I'm pretty impressed.

[Narrator] But vegan cheese,

despite innovations and tastes and creativity in recipes,

still has a problem.

There is no great plant-based cheese

that will melt, stretch, that will bubble, that will brown.

[Narrator] So what's the science behind

why vegan cheese doesn't act like we expect?

[distorted music]

The problem is this tiny protein, casein.

Wired talked to two cheese researchers

to explain the science behind vegan cheese.

It's not found anywhere else in the natural world,

only in the milk of mammals.

So what that really means is that mimicking casein

or replacing casein with a plant-based protein

or some other plant-based ingredient

is extremely, extremely challenging or nearly impossible.

[Narrator] A lot has changed since these videos were made.

Improvements to plant-based fermentation,

the use of new bacterial cultures

and cheese-aging techniques, have created new varieties

of vegan cheeses that smell, taste

and look better than previous versions.

But a vegan cheese that acts and melts

like the cheeses we know and love remains elusive.

What makes casein really special and very, very unique

is that it is an unusual type of protein.

Each protein molecule by itself

has this undefined structure.

If you were able to go to a really fancy microscope,

you would be able to see these casein balls,

but within that ball, we have no clue

how these caseins, like, behave or aggregate

or what their actual shape or form is.

And that is what's really unusual about them,

compared to any other protein.

These cheese variants that are more like cheese spreads

or cream cheese or things that are eaten like on a cracker,

and they don't need to melt or stretch.

It's been somewhat easier to recreate those

and that's why plant-based cheeses

have actually had better success.

[Narrator] The vegan cheeses on the market

run into this problem.

We melted eight different cheeses

and while some did bubble and some even oozed when folded,

they didn't melt like an animal-based cheese did.

So what's the next frontier in vegan cheese science?

Two startups are tackling the problem in different ways.

First up, using a fungal strain to create casein.

The Belgium-based Those Vegan Cowboys started a bounty hunt,

a worldwide call for a fungal strain that feeds on grass

and makes casein without the cow.

There is a bounty of 2.5 million Euro.

Ultimately, we would like to produce the caseins

in the best and the most efficient way.

When you compare bacteria with fungal systems,

we know, for my experience, that fungal systems

can more efficiently produce a homologous proteins

and can also reach higher concentrations.

[Narrator] Second up, using microbes to create casein.

The startup New Culture in San Francisco

is focusing on making a melty, stretchy mozzarella

using precise fermentation.

Fermentation is a process where we would grow a microbe,

or group of microbes, and in that process,

they would be eating food that we are giving to them,

which is sugar.

In a precision fermentation, what is different

is that instead of microbe being fed on sugar

and producing like a lot of different molecules,

we are instructing microbe and making it focused

to produce predominantly one ingredient, the casein protein.

It's a very like empirical and experimentive process

where we did go through thousands of microbes by now,

dozens of variants.

[Narrator] Their vegan mozzarella isn't on the market yet,

but it promises it will have the same melt and stretch

as cow's milk mozzarella.

We basically follow the standard,

the traditional cheese making processes

that have been around for thousands of years,

and then we adapt them to the way our casein exactly behaves

with other plant-based ingredients we use.

There is an enzyme called rennet and historically,

it was actually extracted from animals.

You add it to the milk and this enzyme

will basically gonna force the casein

to coagulate and turn into cheese.

And so this enzyme, rennet itself, is for the last 30 years

made from microbes by using precision fermentation.

It's made in a very similar way

that we're using to make our casein.

[Narrator] Will making a vegan cheese

be enough to persuade cheese lovers to make the switch

to a plant-based alternative?

There is some very emotional response

people have to cheese.

It's like this indulgence product,

whereas with yogurt or milk,

a functional or health product,

and people are just kind of more willing

to have other options.

People, preferentially, do not want to compromise.

And that's why we also say,

we want to use the same ingredients for them,

made in a more sustainable way, without animals,

so that people have the product that they love to eat

and can also eat it in the future.

There is a lot of problems with the industry itself,

as we're aware, growing animals, mostly cows,

industrially imposes the need for large amounts of land

and water to be used and what we're doing

by using microbes to produce casein

and to produce dairy products,

we will require only a fraction of land and water

that's needed for making traditional dairy products,

so it's really like a no brainer.

This is the technology of the future.