And this is everything that's in McDonald's fries.

Welcome to "Fast Food Chemistry."

So, this episode is a little different

because we're not just interested

in the current McDonald's fries,

but also the iconic original McDonald's fries,

which were introduced back in 1955.

We spent weeks working out what we think

is an almost exact recipe for the modern fries

and a recreation of the original fries,

which no one's had access to for 30 years.

I haven't had those since I was a kid,

so I too am going to test the original McDonald's recipe

to see if they're as good as I remember.

Let's get started.

We managed to track down a document online

which apparently contains

all of the original McDonald's recipes.

I too have the McMenu recipe,

with a few changes from Harry

to make it even closer to the original recipe.

The original recipe is potatoes, of course,

sugar, canola oil, corn syrup,

salt, and beef tallow.

I bought one of these,

'cause it said it was 1.5 pounds.

I thought that, "Wow, that's a lot."

Turns out it's not a lot.

Oh. My helper has arrived.

When there are so few ingredients in fries,

there's one thing that makes a big difference,

and that's potatoes.

McDonald's primarily use russet Burbanks,

which we've managed to get our hands on today.

These are a specialist variety of potato

and as a consumer

are a little bit hard to come by in the UK.

This, of course, is a russet potato.

This looks exactly like what I think a potato looks like.

I don't know what the difference between this potato

and other brands or types of potatoes there are.

Whatever the difference is, I don't know it.

According to the recipe that we have,

they should be around a quarter of an inch thick

and 4 to 6 inches long.

Pew.

Almost 6 inches.

5 inches, boom.

We'll do two potatoes.

Get the actual lumps of mud off of this one.

Water's going everywhere already. Good.

Washed.

This is how they do it in the Army, right?

If Gordon Ramsay could see this he'd blow a gasket.

We've gone to the extra effort

of getting one of these fry-cutting machines

so that we can get these nice

even quarter-inch-thick fries.

Here goes nothing.

Bang. Look at that.

That's pretty impressive, though.

Those look a lot like McDonald's fries.

Those look, yeah, pretty similar.

Check out this thing I got.

Here we go. [grunts]

[grunts] Come on.

[grunts]

So, when McDonald's are cutting their fries,

they fire potatoes through one of these grates

at 70 miles per hour.

Unfortunately, we do not have an enormous gas cannon,

so instead we just have me.

Come on.

Then we just need to soak them and refrigerate them.

So, to roughly 2 cups of hot water

I'm going to be adding a quarter cup of sugar

and 2 tablespoons of corn syrup.

2 tablespoons.

Yep, perfect.

Oh, [beeps].

This says "with vanilla."

Doesn't smell like vanilla.

Well, this is the one we're using.

All right, fries going in.

I'm going to put as many as I can

until this thing is, like, overflowing fries.

Whew, that's heavy.

Now it's time for the beef tallow.

It's quite, like, an old-fashioned thing.

I think my grandma used to cook things in beef tallow,

or beef dripping, as it's sometimes called.

Wow, that is very white.

Pure, pure white.

It looks like icing for a cake or something.

But probably tastes quite different.

It's like wax, like candle wax.

Doesn't have a very strong smell to it.

Maybe slightly beefy.

Doesn't really taste of anything.

It's just kind of a little bit chewy

and a little bit greasy, as you can imagine.

For those who don't know,

beef tallow is kind of the fat from the beef.

So when they're butchering up a cow,

they'll carve off the lumps of fat,

they'll kind of render them down to melt them down,

and then let it solidify again,

and this is what you're left with.

What?

So, this is beef tallow, right?

And what I understand

is that this is just rendered fat they use to cook, right?

Did you know anything about that?

I had never heard of this either.

Oh, yeah. What did he say the consistency of this is?

That this is like frosting?

Doesn't really smell like anything.

I mean, it has an odor, but I don't ...

I mean, very mild flavor.

It tastes blank, if that makes sense.

Now we have to find a way to melt this down into that.

It's like cutting the world's greasiest birthday cake.

Oh, wow. That's cool.

Theirs is like a big block of cheese.

This is our beef tallow.

Formula 47, 6 cups of beef tallow.

All right.

Why?

And then half a cup of canola oil.

If my mom cooked a beef Sunday roast,

it would smell like this throughout the house,

which, to me, fantastic.

Time to dry our fries.

This seems like what I'm supposed to do, correct?

Here we go.

Let's take these out.

We'll let them cool for 10 minutes

and then cook them again.

This is our system. All right.

Oof.

Yeah, my boys are soggo.

Get these guys back in there.

Watch out, Cats Domino, this stuff is hot.

And we're going to toss it with some salt.

And there we are. We have old-style McDonald's fries.

No one in this room has ever actually

tried the original recipe, until now.

A one, and a two, and a three. Yoop.

I don't know if this is the right kind of salt.

That might have been too much.

Harry: Obviously, I have to try one of these

while they're still warm.

These are regular McDonald's fries, the now fries.

Now the original "Fast Food Chemistry" fries.

OK, wow. That's really, really good.

You really do taste the beef.

I've never had a McDonald's fry like that before,

and I actually think I might prefer that

to what we have right now.

These are way better.

I might have oversalted them, but it doesn't matter.

Further testing required.

I mean, these are fantastic.

I gotta say, I think I get it.

I think I get why people miss these so much.

These are so flavorful.

It's kind of surprising, because the tallow itself

didn't have that much of a strong smell or a strong taste,

but I think when you cook it, it really kind of

brings out that rich flavor and imparts it onto the fry.

They don't taste beefy.

That's what I was expecting, right?

I was expecting, like, a beef flavor

that maybe I just didn't realize

they had it until they changed it.

But they're just way more flavorful.

I don't know if this is the same with the US right now,

but in the UK, when you buy fries from McDonald's,

they really don't have much flavor to them.

You kind of have to dip them in either ketchup

or barbecue sauce to get any kind of flavor whatsoever.

I think the highest compliment I can pay to these

is that I would happily eat this whole thing

without any dip at all.

I might be speaking too soon,

but I think we need to start the official campaign

to bring back the beef.

These compared to the now McDonald's fries,

these just taste, like, flatter.

They taste like they're missing something.

These guys, oh, man, these are so good.

Harry: These are the only McDonald's fries

anyone under the age of around 35 will have experienced,

and the ingredients list is quite different.

When McDonald's changed the fries recipe in 1990,

it replaced the beef tallow with something

that actually turned out to be worse for you:

trans fats.

They changed the oil recipe again in 2002

to try and eliminate them,

but when this didn't work,

they tried again in 2007.

Now McDonald's says

their fries are completely trans-fat-free,

and it's achieved this through a mixture of canola oil,

corn oil, soybean oil, and hydrogenated soybean oil.

But what's the difference between those last two?

Hydrogenation, as the name suggests,

is the addition of hydrogen.

But when it comes to oils,

that makes a big difference.

Hydrogenation is useful for extending the shelf life of oils

or changing their consistency.

It's how margarine is made.

Effectively, McDonald's has to carry out

a complicated chemical process on its oil

to change something like this

into something resembling beef tallow.

There's one problem, though.

If this reaction isn't perfect,

you end up with trans fats.

These molecules may look extremely similar,

but it makes a huge difference to your health.

Trans fats increase your bad cholesterol

and can massively increase the risk

of heart attacks and strokes.

Yeah, I remember that.

I don't know anything about trans fat,

I don't know what they are, why they're bad,

but it was the talking point for a while.

Should I look it up?

Eh.

We can actually make our own hydrogenated soybean oil,

but I've been told I'm not allowed to do that

because it would involve bringing a tank

of flammable hydrogen into the studio.

Sad.

Yeah, don't do that. Don't bring a tank

of flammable hydrogen into the studio, please.

It has thickened it.

So that's the oils that the fries are cooked in covered,

but there's one other thing that changes them,

and that's the natural beef flavor.

Here's where things get tricky,

because McDonald's will not disclose

what's in their natural beef flavor.

They won't even tell us

if it's meat-based or a vegetarian alternative.

McDonald's previously got in trouble

for not disclosing that they did have beef in them

and had to pay $10 million worth in damages

and issue an apology.

We got our hands on two

very different-looking beef flavorings

to give them a try.

"Beef-flavoring taste test."

Oh, no.

I don't really trust this one,

'cause it's in a very, very blue bottle

and it looks very medicinal,

but I also don't trust this one,

because the label is printed really badly,