All language subtitles for Inside.the.Factory.S08E08.Chocolate.Bars.1080p.iP.WEB-DL.AAC2.0.H.264-VTM_track3_[eng]

Today, we're in York,
once known as the Chocolate City...

Where some of the world's best known

and most loved choccy
brands are made.

There's a proud confectionary
history here,

dating back nearly 300 years.

All right. What are we going for?
Oh-ho!

That one? That'll do me!

All right,
I'll have one of those as well.

Good choice! Yeah? Yeah!

As a nation, we munch our way
through ten billion

chocolate bars every year.

So, where's the best place to find
out how they're made?

What about an enormous factory

that makes some of the nation's
favourites?

I'm Gregg Wallace.
And tonight, I'm the man

with the golden ticket
to the chocolate factory...

..where I'm getting
a magical tour...

Don't worry, if any bits drip,
I'll clear 'em up!

..of the magnificent machines...

That looks like a chocolate shower!

..that create one of our favourite
bubbly bars.

There shouldn't be this much science
in making a bar of chocolate.

I'm Cherry Healey...

Well, hello there! May I? Please!

..and I'm finding out how British

scientists are helping to prevent
a global chocolate shortage.

How long will this plant
stay in quarantine for?

Once that process starts, two years.
Two years?!

While historian Ruth Goodman...

Hello, Alex! Hello, Ruth.

..is investigating... Whoa!

..the bitter history of our
favourite bedtime drink.

It's a fatty, lumpy gruel.

SHE LAUGHS

Every day, this factory makes

more than eight million bars
of chocolate.

And we're going to
revel in just how they do it.

Welcome to Inside The Factory.

This is the Nestle factory in York.

They've been making confectionery
on this site since 1897.

From Kit Kats to Milky Bars,

they produce 65,000
tonnes of chocolate every year.

But today, I'm learning how
they make one of their best sellers,

the chocolate bar packed
full of bubbles,

Aero, in peppermint flavour.

But how on earth do they get
all those bubbles in there?!

To find out, I'm exploring the
remarkable engineering and ingenious

processes that turn out more than
300 bars a minute,

putting the bubbles in every
single piece.

The enormous site covers 58 acres.

That's 38 football pitches!

And at the far end, right on cue,
a very important ingredient...

..is arriving at the intake bay.

Overseeing the delivery is
Line Performance Manager Naomi Lee.

Hey! Naomi?

Hi, Gregg. Good to meet you.
And you.

What's in here? So, this is crumb.

This is one of the very first
ingredients that we use to

make milk chocolate. Crumb?
Let me show you, Gregg.

Oh... so, hang on a minute.

Cos that smells like
a chocolate drink.

Is this what you make the minty
bubbles out of?

No, it's not.

So, this crumb is used to make
the milk chocolate

that we use as the shell
of our chocolate bar.

All right, but you make the bubbles
first, right?

And then you put the shell around
it? That's not the case, Gregg.

We make the shell first
and then the bubbles go inside.

No! Oh, yes! Oh, yes!
That, I've got to see.

This crumb... What is it?

So, inside crumb, we have milk,
sugar and cocoa liquor.

Cocoa liquor comes from
the cocoa beans

and we source these from the Ivory
Coast and Ghana in West Africa.

Right. So is that a liquid?
Cocoa liquor is a liquid.

We process the crumb at a sister
factory in a specialised

facility up in Scotland.

Cocoa liquor isn't alcoholic,

but it is the main
ingredient of chocolate.

It's extracted from cocoa pods,

fruit grown in hot equatorial
regions around the world.

The pods contain beans
that are processed into cocoa liquor

and a fat called cocoa butter.

The cocoa liquor, milk and sugar
are mixed and dried to form "crumb",

a consistent base
for making milk chocolate.

So, how much of this crumb
have we got on here?

So, on this trailer, Gregg,
we have 22 bags.

Each bag is roughly 1.1 tonnes.
There's enough crumb on this trailer

to make over a million
chocolate bars.

Wow! Yes. That should keep us
going for a day or two.

Oh, yeah, definitely.

So, what happens now?
We need to get out the way, Gregg,

so the operators can
unload the truck.

Fabulous.
Come on. Show me the next stage.

As the forklift driver moves in,

the production of my bubbly
chocolate bar begins.

It'll take two and a half hours
to unload

the 22 tonnes of crumb
into the factory.

The cocoa beans used in making my
crumb are grown in West Africa.

But, as Cherry's been finding out,
there's a place right here

in the UK that plays a vital role
in keeping the supply chain going.

Somewhere in the Berkshire
countryside...

..a team of scientists
are working to prevent

a world-wide chocolate crisis.

Because, believe it or not,

the future of chocolate
is always under threat.

To find out more,

I've come to the International
Cocoa Quarantine Centre.

Warm!

This facility is vitally important

because it's the only one
in the world tasked with preventing

the spread of disease in chocolate's
key ingredient, the cocoa plant.

Professor Paul Hadley is in charge.

That is some dirty laundry, Paul!

What's going on?

Well, these are diseases that
absolutely decimate cocoa.

Over here, we've got mirids, which
are an insect from West Africa.

Over here, we've got frosty pod.

And then, here,
we've got witch's broom.

This is another fungus
called black pod.

These are responsible for reducing
the potential

yield of cocoa by about 30%.

The hot equatorial climate
where cocoa plants grow is

the perfect environment
for diseases to flourish.

Across the globe, that could mean
the loss of around

two million tonnes of cocoa beans
every year.

That is absolutely horrendous
because it must affect farmers,

the people who work on the farms.

And the more important thing is

that these are localised to
particular growing areas. Right.

So, if one of these diseases
moved from one area to another,

it would cause even
more devastation.

Every year, cocoa plants are
exported throughout the world

for breeding and research purposes.

To prevent diseases spreading and
to avoid a shortage of chocolate,

samples of these plants must first
be quarantined here in the UK,

to be checked for pests
and diseases by Paul and his team.

What are the consequences
if you make a mistake and something

that comes to you really does have a
disease, but you haven't spotted it?

If one of these diseases,
for example, frosty pod, managed

to get into West Africa, the impact
would be absolutely devastating.

The first person to meet any
incoming plant material is

technician Stella Poole...

..who roots out cocoa
killers by testing

the plants using a process
called grafting,

where the new cocoa plant is
grown on another host plant.

We use a variety called Amelonado
as a mother plant.

It's a bit of a weakling
of the cocoa world.

So, it's particularly susceptible
to diseases and viruses.

Oh, that's so sad!
I know, I know!

But the positive thing is
it will indicate to us

if there's any problems via
the graft with the mother plant.

So, if there is something inside
this plant that is suspicious,

harmful, this plant will pick it up.
Yep.

First, I cut a notch in its stem...

Yeah. Just enough to... Just a trim.

..then I remove a similar
sized piece...

Straight through, all the way along.

..from the bark of our new
arrival... That's what we want!

Yeah, yeah. ..and place it
into the host...

So, it needs to be
bonded on as tightly as you can.

..sealing my surgery with tape.

Over the course of four weeks,

the cells from the two
plants fuse together

and the quarantined plant grows
from the stem of the host plant.

Stella will monitor the host plant
daily for any signs of disease.

We're literally
looking at the whole plant.

And, so, looking at the colour
of the leaves

and they're beautiful,
dense green.

That's beautiful. Yeah.

How long will this plant
stay in quarantine for?

Once that process starts, two years.
Two years?!

There's not enough box sets
on the planet to last that.

There must be a quicker way.

There isn't, it's really
the only way we can be sure.

It's just patience,
just giving it a two-year period

and then we know it's clean.

Only after showing no signs
of infection for at least two

years will cuttings of our cocoa
plant be allowed to leave

the facility
and be sent across the globe.

Now that you know that
this is disease free,

this is not going to cause any harm,
where is this going to go?

It could go anywhere.
West Africa, for instance.

Wow! Yeah.
This is now considered safe.

So, we would happily
export this now, yeah.

It's incredible to think that
in two years from now,

cocoa plants from here
will be providing us

with equatorial cocoa used to make
chocolate bars back in the UK.

Thanks to this quarantine facility,

"Choco-geddon" will remain
the stuff of science fiction.

Back at the factory,

my chocolate crumb, made from
sustainably sourced West African

cocoa, is blown at 60 miles
an hour from giant hoppers

along 100 metres of pipes
to the mixing room.

Proper big smell of chocolate
in here!

This is where the crumb begins
its transformation into luscious

milk chocolate
for the shell of my bar.

What's this?
So, this is our mixer, Gregg.

This is where we mix
all of our ingredients together.

What volume of mix have
we got in here?

We've got about two tonnes
of ingredients in there, Gregg.

How many chocolate bars
is that going to make?

About 67,000 bars of chocolate.

Around 1,000 kilos of crumb
form 50% of the ingredients

in the mixer,
and the rest are added next.

We have sugar, whey powder.
What is it, whey powder?

It's derived from the
cheesemaking process.

Right, OK. Anything else?
And also skimmed milk powder.

Why powdered milk,
why not just use milk?

The water that's inside
the liquid of milk

doesn't mix well with fats.

Clever! Clever!

OK, so in there, we've got
our crumb, we've got sugar,

we've got powdered milk, and
we've got the whey. We do, yes.

They're mixed for ten minutes,

before it's time to add the wet
ingredients through pipes

into the top of the mixer, starting
with even more cocoa liquor.

So, if you just look to your left,
that's cocoa liquor.

Can I try this? Yes, you can.
Is it very, very bitter?

You'll have to wait and see, Gregg.

It's like dipping your tongue
into a jar of instant coffee.

You can tell it's chocolate,
but the bitterness is unbelievable.

Yeah. All right, what else?

So, we also have cocoa butter,
so that's the other jar.

When you say butter, I think,
like, thick, spreadable butter.

But that's liquid. It is liquid.
It can solidify and that's

when you get your cocoa butter,
which is used for moisturiser.

What do you use the cocoa
butter for?

The cocoa butter is adding fats
into the chocolate,

but it also ensures that
you've got that feel

in your mouth,
the silkiness of the chocolate.

Right. Anything else go in there?

So, we have milk fats
and also some vegetable oil.

75% of this mix
is dry ingredients,

so we're adding 25% of wet stuff.

To be honest, even at this stage,
it smells absolutely delightful.

Right. Shall I shut the lid on it?
Yeah, go on. Trust me?

I do, yeah.

Bye-bye, mixer. Hello, next stage.
Come on.

After ten minutes,

2,000 kilos of chocolate mix
flow into a holding tank below.

So, Gregg, this is our finished mix.

That's fabulous!

So, I can't get in there, but I do
have a sample we took earlier.

Well, that's just great
big grainy lumps.

Can I taste this? You can do.

It's nice, but it's grainy,
very grainy.

I can hear it
crunching between my teeth. Yes.

So, at the moment, it's 500 microns,
around the particle size

of the normal sugar that you find
on your table.

The sugar particles in the mix
are just 500 microns,

or half a millimetre across.

But the nerve endings on our tongues
are sensitive enough to

detect that the chocolate
feels grainy.

So what are you going to do with it
now? You can't leave it like that.

No, so what we need to do is
we need to refine the particles out

further to around 30 microns.

You want to make this more refined.

We do, yes. I'm your man.
I'm really refined!

Right, what's the next stage?
I'll come and show you, Gregg.

Good smelling factory, this is.

Very good!

The grainy chocolate whizzes
along a network of conveyors...

..before passing through
two huge sets of rollers...

Mate, size of those rollers!

..where 37 tonnes of pressure
crushes the sugar

particles from 500 microns
to just 30.

So, Gregg, this is the final mix.

It's been through our refiner
process now. It looks a lot finer.

It does, yeah.

And it actually smells more
chocolaty, more intense.

Ooh! Is that for me?
That is for you, Gregg.

Fabulous!

The taste hasn't changed.
It's still chocolaty and sweet.

But the texture is really smooth.

So, you've taken it
from 500 microns to 30. Why 30?

So, anything under 40 microns,

your tongue can't perceive
any grittiness.

Hey! That's genius stuff, isn't it?
It is.

As lovely as it is,
that's still very dry. It is.

It's got to get liquid, right?
Yes, it does.

Well, when do we do that? Well,
we do that in the conching process.

Five hours into production,

and the crushed chocolate mix is
carried by another conveyor

to one of five ten-tonne,
heated mixing bowls called conches.

We do have some additional
wet ingredients that we add.

So, we add some more cocoa butter,
and also lecathin, which is

an emulsifier and actually
binds the mass together.

The conches are heated to
60 degrees Celsius, and three

giant paddles stir the mix
at 25 revolutions a minute,

for six hours!

Luckily, Naomi's got one
she made earlier.

And this is our liquid chocolate,
Gregg. Absolutely lovely.

Conching is the process
of distributing the fat from the

cocoa butter through the chocolate
by heating and stirring the mix.

Glorious! Absolutely glorious!

This coats the tiny sugar
particles in fat,

and after six hours the powdery mix
is transformed.

And for the first time
in the process, we've got rich

and glossy liquid chocolate.

We could paddle in this,
couldn't we? We could.

We could row up and down in it!

Well done. Well done.
Can I see a sample of that?

Yes, we've got some.

I'm tempted to drink it.

Look how glossy that is. Look.

The cocoa is still there, but that
is completely smooth and silky.

This is the key ingredient, right?
This is it. It is, Gregg.

Is it all right if I take this
with me? Yes, of course, Gregg.

Naomi, thank you so much.
Thanks, Gregg.

The factory produces 186 tonnes
of liquid chocolate every day,

enough to fill over 2,500 baths.

Now, that's a fun bath-time!

After conching, my chocolate's
cooled from 60 to 45 degrees,

before it travels along

two-thirds of a mile
of heated pipes.

From Chocolate Making
to Tempering...

..where the factory's
Lead Confectioner, Vikki Geall,

is waiting.

Hello. Is that my chocolate,
that I made?

That's your chocolate

and it needs to be tempered before
anything else is done with it.

I hear the term "tempering
of chocolate". What is it?

It's a stage of cooling
the chocolate down and then heating

it back up slightly to stabilise the
fat crystals within the chocolate.

Let me show you.
I have some samples.

That's a tempered chocolate bar,
so you can see it's nice and smooth.

There's no fat crystals
on the surface.

The chocolate bar next to it is
the untempered one, you can

see the fat crystals forming.

There are three huge tempering
machines here.

We can't look in them,

but Vikki's got a nifty demo of
what's happening inside the tanks.

This chocolate's at 45 degrees,
which is what the

melted chocolate is that's going
through the tanks.

If it cools down,
it's going to go solid, right?

It will do eventually, yes.

So, what we need to do is tip two
thirds of this out onto the table...

GREGG CHUCKLES

And then... And then,
I dip my head in it, right?

You can do, but it's not advised.

So then what we need to do is move
the chocolate about on the table...

Can I have a go? Yeah, sure.

So, what we're doing is mixing
the cold chocolate

that's on the bottom of the table
with the warm

chocolate at the top to try and
create the best structure possible.

And am I doing it? You're
doing it very messy, but it's OK.

The fat in chocolate can set
into six different sized crystals,

but only one type,
called beta five crystals,

makes the shiny chocolate
we need for chocolate bars.

This is such fun!

The six types of crystal
solidify at different temperatures.

Continually moving the melted
chocolate on a cold metal

surface cools it evenly from
45 to a magic 27 degrees Celsius,

while uniformly distributing the
"best" kind of fat crystals.

So, you can see the chocolate's
starting to thicken up. Oh!

Don't worry! If any bits drip,
I'll clear 'em up!

Inside the tempering machines,
five tonnes of chocolate an hour

is going through the same process.
The chocolate's cooled as it passes

over metal plates and agitated
to distribute the fat crystals.

That was a brilliant demonstration.
Thank you, Vikki. Thank you.

So much work's already gone
into making the chocolate for the

shell of my bubbly bars and I'm
only halfway round the factory!

Look, plenty of us
enjoy some chocolate right, but not

always like this,
quite often in a nice, warm drink.

Ruth has been stirring up the sticky
origins of a classic cup of cocoa.

Ah, lovely. Thank you very much.

There's nothing
quite like the velvety smooth,

sweet flavour of drinking chocolate.

But while hot chocolate today
is a delicious indulgence,

it wasn't always quite like that.

The first chocolate bar was produced
in 1847, but for 150 years

before that, chocolate
was consumed exclusively as a drink.

It was first enjoyed by the
17th century equivalent of hipsters,

in special cocoa houses.

By the early 1800s, it was sold
as a drink to make at home,

largely as a health drink.

Historian Alex Hutchison
is serving me up

a hot chocolate from that time.

This is a taste of a type of cocoa
that would have been

available in the 1800s.

They would take cocoa beans, ferment
them, roast them, grind them,

boil them up with milk or water
for about half an hour,

and then you get this
sort of a drink.

That layer at the top
is cocoa butter,

because cocoa beans
contain about 50% fat.

It does look a little
bit oily on the top.

It's not something that disperses
well in water,

it's a fatty, lumpy gruel.

RUTH CHUCKLES

Maybe it tastes better than
it looks.

Oh... That's not what most of us

would think of
as hot chocolate at all!

It's really bitter, isn't it?

There's a sour taste
and a bitter taste. Mm.

There's a lot of astringency. Yeah.

It's reminded me
like drinking an espresso? Yes.

That sort of intense, like, "whoa"
sort of feeling.

This bitter brew was believed to aid
digestion and cure fevers,

so wasn't expected to be
particularly delicious.

Oh... Yeah.

But if hot chocolate was going
to gain mass appeal,

it needed to become, well,
a bit more tasty.

Oh...

In 1828, a Dutch chocolate company
called Van Houten patented

a hydraulic press that squeezed
the beans to remove

half of their fatty cocoa butter.

The result was cocoa powder.

This made a much less oily drink

and Alex is making me a cup.

So, if we were to mix this powder
with hot water...

..you don't get that oily scum.

I see what you mean.
It looks so much cleaner. Mm-hm.

The Dutch company had improved
the texture, but how was the taste?

Oh, my goodness! That's bitter!

That's more bitter
than the other one!

The cocoa butter was masking
some of those flavours

and that bitter taste, and now that
we've removed the cocoa butter,

it's bringing out... some
astringency.

In 1846, Coenraad Van Houten
finally cracked the problem,

with the help of a simple
store cupboard staple.

Here we have bicarbonate of soda,
and if you would like to put

say half a teaspoon into this glass
here... This glass of water.

..and just stir it up.

That is so different. That's...
All that bitterness is gone.

It still tastes really chocolaty,
without being bitterly chocolaty.

Smooth and rich.

Van Houten discovered
the bitterness was

caused by naturally-occurring
acids in cocoa beans.

Adding an alkali like bicarbonate
of soda neutralised the acids

and resulted in a much
sweeter tasting drink.

The acidity was gone, it's much more
easily dispersible in water.

This is a product with mass appeal.

This delicious cocoa was a hit
and Van Houten's methods were

eventually copied by UK
chocolatiers,

like Cadbury's and Rowntree's.

And nowadays, this method of making
cocoa powder is still called

Dutching, paying tribute
to its inventor every time

we indulge in a comforting cup.

Back in York, there's no
bitter problem

with my velvety liquid chocolate...

..which is on its way to become
the shell of the bubbly bar.

So many pipes!
There's pipes everywhere.

It's a maze of pipes!

There are seven miles of pipes
running through the factory,

and these ones are heated to 29
degrees Celsius to maintain

those good fat crystals...

..as the chocolate
heads from Tempering to the

start of the Production Line.

It's the heart of the factory,

extending 53 metres through this
massive cathedral of confectionery.

And I'm finally ready to start
moulding the chocolate

shells of my bubbly bars...

..with the help of this
Yorkshire Willy Wonka,

Line Performance Manager
Dan Fieldhouse.

Dan? Gregg.

What's happening to my chocolate,
please?

So, the chocolate's travelling
into the depositor,

through this pipeline here,
into a hopper in the top.

That looks like a chocolate shower!

What that's doing is acting like a
filter, filtering the chocolate

into the top of the depositor.

And the depositor,
is that that funnel there?

That's correct.

So how much chocolate is being
held in that hopper?

There's round about 200 kilos of
chocolate in it when it's full.

Right. Then what happens?

The chocolate then
sits in the hopper,

and then it passes through
the depositor,

and these plastic moulds travelling
underneath, the chocolate's

deposited into each one of these
plastic moulds.

My lovely shiny chocolate,
now in the mould!

More than 1,700 plastic moulds
fill the production line,

each holding 12 bars.

They've got dimpled bottoms
to create

the curves on the top of the bar.

As they pass under the depositor,
they're filled with

exactly 130 grams of chocolate
at 27 degrees Celsius.

The chocolate's going into the
mould and over-filling the mould.

This is creating the top of the bar.

So when it's turned over,
that's the rounded part of the bar.

That, right now, is beautiful
and shiny,

but that looks like a solid
chocolate bar to me.

Right. And the next part of the
process is to take a little bit of

that chocolate out of the mould.

You put it in and then you take
it out? That's right. We do.

You're not kidding me, are you?
I'm not, no.

You put it in to take it out.
We do, yes.

The depositor fills
28 moulds a minute.

That's over 20,000
individual bars an hour!

The conveyor belt vibrates
to remove air bubbles

that could weaken the shell.

So, describe what's happening
there to me.

So, the mould
is turned upside down

and the excess chocolate is dropped
out to create a shell.

What do you mean the excess
chocolate? It's all coming out!

It's not. A thin layer of chocolate

sticks to the inside of the mould
and that creates a shell.

The moulds are also heated
to 27 degrees Celsius to keep

the chocolate at just the right
consistency.

If it's too hot,
too much chocolate will pour out.

If it's too cold, too much chocolate

will stick to the mould
and not enough will come out.

And, of course, the viscosity
is really important here, then.

Vitally important.

So, thanks to Vikki
and her tempering machines,

the liquid chocolate is thick enough
to coat the mould to form

a shell precisely 1.2
millimetres thick.

Do you mind if I stay and watch this
for a bit? Not at all.

Actually, if I hadn't seen it,
I wouldn't have believed it.

Just the right amount of chocolate
stays in to make that shell.

Exactly the right amount
of chocolate, yeah.

There's no waste.
The chocolate that's tipped

out of the moulds goes back to
the start of the production line.

Ingenious!

Absolutely ingenious.

And so are these lifts, which
carry my moulds up to chillers that

run above the production line.

The filled moulds spend the next
20 minutes at ten degrees

Celsius, which sets the tempered
chocolate into a shiny shell.

So, we've got the top half
of the chocolate shell, but this is

a minty bubble bar, so now we need
that all-important green filling.

All right, Dan. We're making
our middle now, are we?

Yeah, this is the point where we
make the centre.

So, the filling is sent
over from the tank over there

and brought over to this area here.

I've got a sample of it here.

So this is supposed to be
our minty bubbly centre.

That's got no bubbles in it, and
it's definitely not minty.

Not yet, we add the colour
and the flavour next,

and after that, we add the bubbles
later in the process.

So what's that, then?

That's powdered milk, it's vegetable
fat, sugar and butter.

Can I have a taste? Go ahead.

It's definitely not minty. It's
like a very sweet banana milkshake.

It's extremely sweet.

All right, so now we've got to
add colour

and we've got to add mint flavour.
That's right.

Right, OK, how do we do that?

First, we add the colour.

How much of this do you need, the
colour? We put in 4.92 kilos.

How do you actually make
this green colour?

This is made from chlorophyll,
which is a natural plant extract.

And then it's taken from plants
such as nettles and grass.

It's quite a bit, isn't it? Yeah.

There you go, 4.92.
Now, what goes in?

2.8 kilos of the flavour.

I bet that flavour is pungent.
It's really strong.

Wow!

That is like mint on steroids!

It's really nice, but it's almost...

It's so strong,
it's almost clinical.

Yeah. How do you make
the mint flavour? Is it mint?

So, this is a natural extract, which
is purely taken from peppermint.

It must come from tonnes
and tonnes of mint leaves.

What do I need here?

2.88.

The mint flavour
and green colouring are separately

and precisely weighed to ensure
one tonne of filling will become

the perfect centre for my bubby bar.

There you go. Perfect.

So that is seriously green
and seriously minty!

How many bars is that
likely to make?

That'll make around 50,000 bars.
I'm not surprised.

But we've now got to get this green,
minty bucket

into the white mixture, right?
Where does that go?

So we put it inside this mixing
vessel. You literally pour it in?

That's correct, yes. So, all this
millions of pounds' worth

of machinery and you literally pour
a bucket-load in. That's right.

I love you for that,
you know that!

I'm really chuffed
I didn't spill a drop. Not a drop.

What's next? Next,
we add the bubbles. Yes, come on!

This is the bit everyone
wants to see!

This is the moment
I've been waiting for

since I arrived at this factory,
the secret of bubbly bar building!

This is the bubbles?!
I can't see any bubbles.

So, the filling travels down
this pipe into the machine.

And then at very high pressure,
liquid CO2 is put into the filling.

So, you're not putting
bubbles into the mix?

No, it goes in as a liquid.

Ah! So, you're pumping a liquid
at high pressure into something

that's already a thicker liquid?
That's correct.

As a gas, carbon dioxide makes
the bubbles in fizzy drinks,

but under pressure,
it becomes a liquid.

So, they're not bubbles here.
They're not bubbles here, no.

No. You're putting bubble mixture
in to make bubbles later?

Yes, that's right.
You're tricky you are, Dan, tricky!

So, when do the bubbles appear?

The bubbles appear when we put the
filling into the shell, over here.

Like everything in this factory,
creating bubbles is more

complex than it looks
because it's a two-stage process.

Our minty middle is now
full of carbon dioxide,

and over on the production line,
336 chocolate bars

a minute are descending in the lifts
from the chillers ready for filling.

They're heading for the filling
depositor,

otherwise known as the bubble maker.

And here they are.

There you go, Gregg, we've got
the bubbly centre in the shell now.

You have. Yeah, you can clearly
see it.

How's the green filling
got in there, please?

So, the filling travels through
the pipework into the depositor,

and then it sits in the depositor,
and it's pushed down into the mould.

I can see that happening.

So, the CO2 is
dissolved in the filling.

When it hits the atmospheric
pressure,

the CO2 then changes back to a gas
and becomes a bubble.

So, under high pressure,
the CO2 is liquid?

That's right.

When it comes to normal pressure,
like now, it turns into bubbles?

That's right,
that's where the bubbles are formed.

It's the same magic as getting
squirty cream out of a can.

Each of the bubble maker's nozzles
deposits exactly 1.6 grams

of minty green mix into the shells
below, 12 bars at once.

As the mix hits the air, the liquid
carbon dioxide dissolved in it

instantly turns into a gas,
creating the bubbles.

I've got a suspicion there shouldn't
be this much science in making

a bar of chocolate. So, that green
frothy bubbly mixture,

that's only on one half the shell,
right?

Where's the other half of the shell?

Don't worry,
Gregg, that will come next.

My bars are two-thirds of the way
through their factory journey.

We've made their curved
chocolate top,

and thanks to CO2, they've now
got their bubbly mint filling.

Carbon dioxide isn't just used to
make the bubbles in my bars.

It's also what makes fizzy
drinks, well, fizzy!

So, what's the history of bubbly
beverages?

Ruth's investigating.

There's nothing like a burst of fizz
to brighten up the day.

We drink a staggering five billion
litres of fizzy drinks every year.

But who on earth came up with the
idea of putting gas

into our drinks in the first place?

The brain behind the bubbles
belonged to an amateur scientist,

Joseph Priestley,
who was inspired, in 1767,

while hanging around
his local brewery...

..which is where I'm finding
my science historian mate...

Abs!

Hello, Ruth! Hello!

..Abs Wisdom.

And I find you in a brewery! What
a great place to be, though, eh?

So, who was this
Joseph Priestley, then?

He was an amateur chemist.

He became fascinated by the froth
that came off the top of the beer,

and he looked at it and wondered
what was causing that froth to rise.

What on earth does Joseph Priestley
think is going on in the beer?

This is the 18th century,
when chemistry is in its infancy.

People know very little
about the natural world

that's existing around them.

Now, one substance that people
were investigating was this

mysterious thing called fixed air.

And Priestley thought that fixed air
was what was causing

the bubbles in the
fermentation barrel.

Priestly set out to capture
some of this "fixed air",

which we now know
was carbon dioxide.

Brewer Dave Daniels is helping us
mimic the experiment.

Seems a bit odd, trying to scoop
something you can't see.

If we're successful...
I don't know if I've got any.

..fixed air should have
an immediate effect...

Well, let's have a look.
..on a naked flame.

Look! It's extinguished the flame.

A flame needs oxygen to burn and
there was no oxygen in fixed air.

So, how do we go then
from fixed air, carbon dioxide,

to fizzy drinks?

Well, in the 18th century,
people from Europe would visit spa

towns to take the waters.

Many of these had
a slightly fizzy nature to them

and were thought to be giving all
kinds of health-giving properties.

In some spa towns, people would
drink the natural spring water,

rich in minerals like sulphate,
calcium and chloride.

Priestley thought that infusing
ordinary water with

carbon dioxide bubbles would make it
into a health drink, too.

And we're going to replicate
Priestley's experiment, with

the help of some crushed chalk...

There we go, bit more...

Yup, that's good. Right...

..and sulphuric acid. Here we go.

Don't try this at home!

The powerful acid reacts with
the calcium carbonate in the chalk

and the chemical reaction
gives off carbon dioxide gas.

OK, so let's get the top on there.

And now, we're going to get
this little tube

underneath and into
our inverted container.

Happy? And now, if we pump this just
a few times, it should draw the

fixed air from this container,
through this pipe

and up into this vessel here.

So, give that a few gentle pushes.

Priestley used a pig's bladder
to collect carbon dioxide

and infused it
into the ordinary water.

There we go. And that is your fixed
air coming into this water.

OK. That's great, there we go
and now, we will agitate it.

So, now, we're dissolving the carbon
dioxide in the water itself.

He discovered shaking helps carbon
dioxide dissolve in water.

My arms are aching, you have a go.
All right.

It's a process known as carbonation,
and thankfully, modern

machinery does the job for today's
fizzy drinks manufacturers.

There we go.

So, what is the difference
then between what we've just

produced and what you would
buy in a modern bottle?

Well, pressure.
A modern-day soft drinks company

would be injecting the carbon
dioxide into a sealed container

at a much, much higher pressure.

And it has nowhere to go, but to
mix in with the drink itself.

So, essentially, this is the modern
process just without a little bit

of additional pressure.

Yeah, Priestley was really on to
something.

Sadly, Priestley's fizzy water
didn't take off as a health drink.

But his experiment eventually led
to today's carbonated soft drinks

industry, worth over £8 billion
annually in the UK alone.

At the factory in York,
the ingenuity of modern

engineering has used CO2 to create
the bubbles in my minty bars.

It's 14 hours and 46 minutes
since production began,

and my bars have the chocolate
shell for the top...

Very impressive! But it would be
even more impressive

if I could get in there with them.

..and their peppermint filling.

They've spent the last 27 minutes
in the chillers up above us.

And now they're ready to
pass beneath one final depositor.

Right, Gregg, here we are.
We're putting chocolate on top

of the bubbles now
and creating the bottom of the bar.

I just love the uniformity
and the precision.

And not only that,
it's a load of chocolate!

What's happening here, Dan?
So this is the backing off process.

We've got the chocolate
on the backs of the bubbles.

And then, we have these blades
that are taking the chocolate off.

The first blade's taking off the
excess chocolate and the second

blade is taking off a lesser amount

and creating a smooth back on the
bar.

You like it here, my friend,
don't you? Yes, I do.

Now, York has a brilliant tradition
doesn't it, of chocolate making,

and chocolate excellence.

Do you feel any sense of pride to
keep that tradition going?

Yes, I do.

My father used to work here
and my brothers worked here.

And it's still one of the biggest
employers in York.

What I'm looking at here isn't
the top of the bar, is it?

So this is actually the top
of the bar, as it's travelling
through the process.

It starts as a shell, upside down,
and travels through the
whole process upside down.

Cos you finish with the bottom,
you call it the top! Yes!

Mate, how do you expect to get
anywhere with that?!

That's ridiculous!

But this is the bottom of the bar,
isn't it? It is.

If you imagine it in a shop,
that's the bottom of the bar. Yes.

So now, we've got 50% centre
filling and 50% shell and back.

And a brilliant process it is too,
Dan. Well done!

Once the bubbly filling is
encased in milk chocolate,

the bars get a final
lift to the cooler,

before heading to the noisiest
machine so far.

What's that banging?
It's like someone's trying to
get out! What is that?

RHYTHMIC BANGING

So each mould is hammered three
times to drop the bar onto the belt.

They're actually
like the hammers on a piano.

They are exactly the same.
It's a giant version.

So, why the three times like that?

Because it's the front,
middle and back of the mould.

Can I see them come off?
Yeah, so come down here.

There they are. Look at that,
precision.

It's like a regiment
of chocolate bars!

That's a fabulous sight, isn't it?
It is. That really is.

Bar after bar.

And a great shine on that.

That's the tempering
I learned about, isn't it?

Am I allowed to pick one up?
Yes, go for it.

It's shinier on the top, there,
than it is on the bottom. Yes.

It's really good.

How many bubbles are in there?
There's 80,000 bubbles in a bar.

No, are there really?
There really are, yes.

I was only kidding!
Someone knows how many bubbles...?

Yeah, they actually do.

Actually, it doesn't surprise me.
I love that.

That is really precise.

Like the curves of that really fine,
snappy, shiny shell.

I mean, that's proper precision
there because that is fine and thin.

Am I allowed to have a...?
Yeah. Go ahead.

You can't taste bubbles, can you?

You can't taste air,
but you can certainly feel them.

You don't need to chew. No.
They dissolve on your tongue.

Precision engineering creates
perfectly tempered chocolate and

clever chemistry uses carbon dioxide
to make thousands of bubbles.

Put them together and you've got
a special confectionary experience
in a bar.

It was worth all the effort.

Clever. Very, very clever!

Listen, thank you so much
for showing me around.

That was far more complex
than I ever thought.

It's a topsy turvy business,
making the top of the bar first,

then the middle,
and then the bottom.

But Dan and the team know
what they're doing.

As we know, the colouring that
gives our bubbly filling its green

hue is made from natural
ingredients.

So how are plant-based food
colourings made?

Cherry's finding out.

When it comes to colour,
nothing beats nature...

RECORD NEEDLE SCRATCH

..except maybe some beautiful
pink chocolate.

So, I've come to the multi-hued
City of Bristol to find out how to

add a kaleidoscope of colours to
food and drink using only plants.

Natural food dye expert
Giles Drewett is helping me...

Hello. Hi, Cherry.
Lovely to meet you.

..to come up with a food colouring
to turn chocolate, not peppermint

green, but my favourite
colour, pink!

Can I use these strawberries
to colour my chocolate?

Unfortunately, the pigment that
is inside the strawberry, whilst

it's quite pink on the outside,
is quite weak on the inside.

So, we don't get enough colour
to then colour chocolate.

So, if strawberries are a no, how am
I going to colour my chocolate?

You need beetroot.

Unlike strawberries, that are only
red on the outside, beetroot

are coloured throughout with a deep
purple pigment called betanin.

They're cheap
and easy to source for making dyes.

So, we've got our beetroot.
Let's go.

At his factory, Plant EX, Giles
also takes delivery of other fruit

and veg, like carrots
and red cabbage, for his dyes.

Juice is easier to transport
than whole veg.

Wow! That is
a lot of beetroot juice!

This juice from Turkey has been
cooked down to remove two-thirds

of the water, removing taste and
aroma, but leaving behind....

Oh, wow! That's really beautiful,
actually!

..an intense betanin syrup.

It's the most incredibly
deep, rich, purpley-pink.

I just think that's
a thing of beauty.

But the syrup is too wet to use
to colour my chocolate.

The remaining water would moisten
the sugar particles, creating lumps.

So, it needs to go through a process
called spray-drying.

First, the syrup is turned
into a fine mist.

Then, the remaining water

content is driven out by a jet
of hot air, leaving a powder.

Next, the powder is mixed with oil,

so it will blend
evenly into fatty chocolate.

But it still needs to go through
one final process.

So, what is this?
Cherry, this is our bead mill.

Bead mill? That's right.

Giles has a sample of the oil mix
to demonstrate what's

happening inside the machine.

We've made the red beet
juice powder.

And we've got vegetable oil.

And we've put the two of
them together.

But as you can see...
Why have they separated?

The powder has sunk to the bottom
of a mixture because the particles
are too big.

And what we need to do is to divide
that down into tiny pieces,

small enough that it will
stay in the suspension of the oil.

So, we'll add these tiny ball
bearings into the mixture.

Look at... These are so weird!
They're like almost tiny pearls.

The aptly named "bead mill"

is loaded up with 175,000 of these
one-and-a-half-millimetre

diameter balls, which are made from
a hard, heatproof, abrasive ceramic.

This is a mixture now which
contains the balls and that's

rotating at 1,400
revolutions per minute

and that's gradually grinding
the size of the powder down from

around 16 microns to half a micron.

That's a hundred times thinner
than a human hair.

So, you use these almost like
a pestle and mortar. That's right.

How long does this process take?

It could take anything between
48 hours and two weeks, depending on
the pigments. Two weeks?! Yeah.

Because of their varying texture,
different fruits

and veg take different
times to mill.

It takes 72 hours before the beads
are sieved out of my beetroot mix

leaving behind a completely
natural colouring,

used in foods like smoky bacon
crisps, pink custard,

and chocolate!

So, here it is.

Is this it? Red gold.
This is the final product.

Look at... Wow!

Look at that!

I mean, it's a lot of work
to turn something pink.

Well, hello, there! May I? Please.

That's so tasty, but there's
definitely no hint of beetroot.

OK, I'm going to try one of these.

I love my job!

In York...

..it's just over 15 hours since
the start of production

and my finished bars, complete
with their natural green filling,

are rumbling
along from the Production Line...

..to Packing,

where I'm meeting Line Performance
Manager Simon Lindsey.

Simon, I tell you, I love packing.
I think it's got to be

one of my favourite bits. Show me
how you pack these up.

So, the bars we made earlier,
they're held in place by a vacuum,

like a reverse air hockey table.

Sucking it onto the conveyor?
Yeah, holding it nice
and firm in position.

But you'll notice on the wrapper,
we're a cold seal process,

only glue lines,
no heat to seal it, just pressure.

This process is called flow-wrapping
and doesn't use any heat to

seal the wrappers, which could
melt the chocolate.

And that is a perfectly wrapped bar.

There we go. How would you open it?
Honestly? Go for it.

I normally take a bite at the end
like that... Yeah.

..and then just rip it. Yeah.

So... That's bad though, right?
The correct way,

"peel and reseal".

The benefit of having a cold glue
line is that you can open

the bar... So, portion control,
Gregg.

What we don't want to do is
eat a whole bar in one go.

We can eat what we like...

..then we can seal the bar
back up, ready for later.

That may well and truly
revolutionise my life!

Yet another clever machine

that processes over
300 bars a minute.

Next, a robot places 15 wrapped
bars into each box.

And they're lifted onto a conveyor
belt, circling above our heads.

Where are the boxes going?
Off to dispatch. This way.

More robots place the boxes
onto pallets

and wrap them in plastic,
ready to leave the factory.

Nice! So, this is dispatch, Gregg.
Very good!

Right, go on, tell me. This is
where our lorries are loaded.

52 pallets go onto that lorry,
Gregg.

How many boxes on there?
Where's the numbers?

Each pallet contain 240 boxes.

That's 3,600 of our bubbly
bars per pallet.

Over 180,000 bars of chocolate
on that lorry, Gregg.

You don't store them anywhere?

You've got no storage of these
bubbly bars?

The lorry is filled,
it's taken away.

The next one's back up onto
the dock, ready to go.

Hang on a minute. So, how many
trucks are leaving here every day?

Three full lorry loads of bubbly
bars leave this site every day.

Well, how many individual bars
is that leaving the factory?

That is just over half a million
bars every day of the week.

But if you're not storing them,

that means you are dispatching them
as fast as we're eating them.

Pretty much. Yeah.

And if you laid them end-to-end,

those half a million bars a day
would stretch 50 miles.

That's from York to Grimsby!

York has a great history,
fine tradition of chocolate making

and this factory has been
here for a long time.

Do you feel yourself
part of that tradition?

Do you take pride in that? Yeah,
you've got street names, areas,

tourist attractions,

chocolate shops, all telling
the long history of York.

And you can smell it in the city.

You cannot get away from that
lovely smell of chocolate, Gregg.

And you're a part of that.
You're a big part of that.

Yeah, it's an absolute honour
to be part of that.

That's it, innit? Last pallet?
That is, last one full.

Thank you very much indeed.
No problem. That was great.

Now, you get on because the nation
needs its chocolate.

I'll make sure it gets out
straight away.

It's been just over 18 hours

since we took delivery
of our chocolate crumb, and now,

the finished bars are ready
to leave the factory.

Soon, people will be breaking
into their bubbly bars

across the UK and Ireland.

The factory makes six
different flavours

and peppermint is the most popular,

accounting for 60% of sales.

What I've seen here is
state-of-the-art engineering,

producing chocolate bars
on an enormous scale.

From precision mixing
and filling...

..to creating millions
of high-tech bubbles...

..there's more science
going into these bars

than I would ever have believed.

But of course, they're following
a tradition of chocolate making

that's been going on here
for over 100 years

and that is very, very impressive.

The factory has come a long way from
its first, early assembly lines.

But how did
we get from there to here?

Explore the history and the future
of the factory,

on an interactive timeline.

Go to...

..and follow
the links to The Open University.