Melt in the Mouth Food Factory

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Have you noticed how some snack foods seem to melt in your mouth?

Here are two of my favourites.

Cheesy puffs and chocolate-covered honeycomb.

But why do they melt in your mouth?

To find out, we're going to make our own from scratch.

We think we know these foods,

but how much do we really know about them?

OK, budge up there.

One, two, three, go!

Oh, yes!

Have a taste and tell me what you think.

Crispy at first and then it just dissolves in your mouth.

-What goes on in your mouth?

-It dissolves on your tongue.

-Do you like these honeycomb bars?

-Yes.

-Why?

It's the softness of the chocolate

and yet the hardness, crunchiness of the honeycomb centre.

Can you grab a piece of the honeycomb bar?

Why do you think it's so light?

It's obviously got air bubbles inside it, hasn't it?

When I was a kid, I used to get into trouble for playing with my food.

But now that's what I like doing most.

I love finding out what happens to the stuff that we eat.

But finding out what factories do to our food isn't easy.

So to copy the big boys, I've set up my own food factory here in this barn.

To help me discover what the masters of mass production do,

I'm going to need some factory workers.

Clocking on for today's shift are consumer champion Esther Rantzen

and her daughter Becca Wilcox, the Watchdog reporter.

But whose version of today's supermarket food

will go in the basket and whose will go in the bin?

LAUGHTER

Our shift at the Food Factory is about to begin.

MUSIC: "Rubber Biscuit" by The Chips

-Brilliant to see you. Thank you for coming.

-Our pleasure.

-Do you like chocolate?

-Puts me in a good mood.

-Fantastic. Becca?

-I can't say I do.

-How do you raise a child who doesn't like chocolate? Brilliant idea!

Well, it means more for me. THEY LAUGH

-I will eat it, especially if there's competition involved.

-THEY LAUGH

-This is what we're going to be making.

-Oh, wow! I haven't had this

since I was about 12.

Mm!

-Mm!

-Mm!

Now, what we need to do is find out what this strange centre is made of

and how they get all of the bubbles inside it.

-Wow!

-Too late to go home.

Making these melt-in-the-mouth snack bars

is much harder than it looks.

Becca's not going to be going home for a while yet.

-OK, you all set for this?

-Yep.

-Yes.

-Excellent!

-So your challenge is to make two rival bars.

-OK.

But using the same techniques that they use in a factory.

And then we're going to take your efforts outside

and offer them to some taste testers who will decide which one's best.

Those poor people!

HE LAUGHS

So, the whole journey...starts here.

-Ah!

-Ooh, yum!

-Meet your ingredients.

-Chocolate.

Lots of chocolate, obviously. It's a chocolate bar. Lots of sugar.

But then...we have some mystery ingredients.

-Oh!

-Strange gloopy, globby stuff.

And this...mystery white powder.

So the first task you've got is to make the honeycomb centre.

-Let's get to work.

-Indeed.

'It's not easy to unlock the secret of those honeycomb bubbles,

'so my two trusty factory foremen, Marty and Tod, are here to help.'

This really is chemistry. We've got to weigh the right amount of sugar,

-the right amount of syrup, glucose syrup.

-OK.

Add some water and boil that up in a pan.

-We'll put all the sugary stuff in there.

-OK.

And then we're going to use this beast...

-flame gun...

-Love it!

..to heat it up.

And then we'll do the chemistry.

-Do the chemistry? Just do the chemistry.

-Do the chemistry!

We're making an item of confectionary,

so of course there's a bucketful of sugar to melt.

And yes, we'll also need some clever chemistry.

Now, to get this honeycomb stuff right,

they need to mix up lots of sugar together with this stuff.

It's called glucose syrup. You really need that

to be able to get your honeycomb to set very, very hard.

This syrup is too watery

so they need to boil it to get rid of some of that water.

Come on, come on.

Yeah. Pour a bit out, Esther, come on.

Come on, stuff.

Esther and Becca have to heat up the sugar and glucose

to just the right temperature. This is really important

otherwise their munch bars won't have any crunch.

We need to get it up to the hard ball temperature.

-Which is?

-150 degrees.

It's where the mixture will take on a particular gloopiness.

-That's the technical term?

-Yes.

When the temperature reaches 150 degrees centigrade,

they can add the next ingredient.

And it's a bit of a surprise.

This is bicarbonate of soda.

It's the key to getting the bubbles in your honeycomb just right,

because when you heat this stuff up, it gives off gas.

Lots of it. Watch this.

Let's see what happens when I heat up the bicarbonate of soda.

Whoa!

LAUGHTER

-It went.

-It went.

When bicarbonate of soda gets hot,

it creates bubbles of carbon dioxide.

But it's not that easy to control this chemical reaction.

You've got your molten sugar at the perfect critical temperature. Start those production lines!

The big challenge facing Esther and Becca

is can they make these bubbles just right?

-All systems go now.

-Are you ready?

-Here we go.

-Here we go.

-Do you have to stir it?

-We've got to stir it.

Oh, look! It's going really fizzy-bubbly!

Watch out. I'm going to be pouring that in a moment.

Ooh!

-Shouldn't there be bubbles?

-Oh, there will. Just watch.

-The masterpiece!

-Chemistry over.

Becca's cock-a-hoop with her result.

But it hasn't gone so well for Esther.

What's happened?

Well, we think probably that most of the carbon...whatever it's called

-stuck to the bottom of the spoon.

-It's still there.

-It's still there.

So while I was expecting this massive eruption of bubbles,

-what we got was that.

-You don't know what's inside there.

If there's a fizz of bubbles underneath the surface,

-it might be salvageable. Good luck.

-Thank you.

Not a chance.

-Becca!

-I know!

-That looks brilliant!

-Are you impressed?

The big question is what's it like inside?

You've got these big bubbles on the top.

If they're inside, it won't be like the ones you buy in the shops.

-And that's what we're after.

-It's a slight worry.

-We'll only find out when we start cutting it.

-Well done.

Now they need to turn this bubbly swamp into bars of Crunch 'n' Munch.

OK, pretty good so far.

But now you need to cool it and cut it. And I want standardised shapes.

They've all got to be exactly the same size bars.

Because this is a factory line, not a kitchen, OK?

# Bow-bow-bow-bow

# Bow-bow, ooo-ooo-ooo-ooh. #

Will Esther and Becca be able to make a bar our taste testers can munch?

I'll leave them to it while I search for the secret

inside another melt-in-the-mouth snack.

Are you two fans of the cheesy puff?

We are fans of the cheesy puff.

-Quite light. Don't weigh you down.

-Crunchy at the same time.

They start off nice and crispy, then the moisture in your mouth melts them to nothing.

It's a melt-in-the-mouth sensation.

I think the way it dissolves or disintegrates

is what makes it different from other crisps.

Why do you think they make it so that they melt in your mouth?

So you want more.

But what are they made from?

And why do they melt in the mouth?

To melt down the secrets of cheesy puffs, I'm going to make my own.

Cheesy puffs are made out of this stuff, maize.

Grind up these kernels and you end up with this.

Eurgh! It's like eating sand.

So, how do you turn it...

into cheesy puffs?

Boil it up, maybe.

Nope.

Roast it?

Nope.

Fry it?

No!

To transform unappetising maize into light, airy cheese puffs,

they cook it in a way that no domestic kitchen can copy.

We're about to discover a bit of kit

which makes weird and wonderful food shapes possible.

Meet the extruder.

It was patented 70 years ago by a cattle-feed company.

The raw maize goes inside and a tightly-fitting spiral compacts it.

As the spiral turns, it forces the maize down towards the end.

And the force gets harder and harder and creates heat,

so much heat that when the maize

finally gets squeezed out of this tiny little hole here,

it's so hot that it cooks it and you get corn puffs.

But the spiral needs to spin very fast

to force the maize through the hole.

I'll never get up enough puff.

That's hard work. I need more power.

This should do it!

The output at the back of the tractor will power my extruder.

The spiral's up to speed

so if I ladle in the maize, I should get puffs out.

Look at them coming out! Oh, they're a little bit wiggly.

A bit more stringy than puffy.

That's disgusting!

It's like worms!

But now the shaft's getting hotter and the maize is going gooey inside.

It's beginning to puff just a little bit.

I can feel the heat off it. It's its own cooker.

Whoo! Ha-ha!

It's shooting them out.

Blimey! It's really fast!

As the hot, squidgy maize pops out,

the moisture turns to steam

and the maize magically puffs up.

It's a-maizing!

Look at that! That is absolutely brilliant!

Look! I've got puffs!

Maize is the only ingredient.

What really makes these melt-in-the-mouth snacks possible

is the machine.

It's time for quality control.

Some of them look a bit weird and gnarly.

Some of them are short and bally.

Some of them are...

a bit mad.

THAT is a brilliant corn puff.

Look at it! It's got the right shape.

Oh! Ah-ha-ha!

It's got the right texture.

Beautiful aerated little centre.

THAT is brilliant!

The puff is up to 90% air.

That's why they melt in the mouth.

The thing is...

..at this stage, they don't taste of anything

and that's cos they're naked corn puffs.

But wait till I coat them in this stuff.

Cheese-flavoured powder.

It's about 7% cheese.

And if I mix it with oil to make a paste,

it should stick to my puffs.

Got my corn puffs, I've got my flavouring.

In the factory, they put these together in a huge rotary oven

which tumbles them all around, heats them up

and coats the puff with all the flavouring.

I've got a tumble dryer.

Now the flavouring.

If this doesn't make them cheesy, I'll chuck my socks in as well.

After they're baked in this lovely cheesy paste,

they should be ready to eat. Take a look.

Fantastic! They're all covered with a little film of flavouring.

Not quite as cheesy and not quite as fluffy as the real thing,

but considering what it's been through, I'm well chuffed with that.

My very own melt-in-the-mouth cheesy puffs.

But only our taste testers can decide

whether they're as good as the shop-bought ones.

Dig in, grab yourself a handful of those.

What's the magic going on inside your mouth right now?

-It's quite plain.

-Ha!

-And what's the texture?

-Nothing.

-Nothing!

-Air.

-Air, yeah. It's mostly air.

-Is the texture right?

-Yes. I reckon so.

-I'll take that!

-It sort of melts in your mouth.

-That's exactly what I'm after!

# Bow-bow-bow-bow

# Bow-bow, ooo-ooo-ooo-ooh. #

Back in the barn, mum and daughter Esther and Becca

are making rival Crunch 'n' Munch bars.

The hot honeycomb slab has been cooled down

using some industrial-inspired ingenuity.

LAUGHTER

Oh, dear! Making Crunch 'n' Munch bars

is proving trickier than expected.

-This is what we meant to happen, is it?

-Yeah, this is good.

The honeycomb is now cold enough to cut.

But can they produce finger-shaped bars?

I think we can use a red-hot wire

that will just melt its way through the sugar.

-Brilliant. Am I going to do that?

-Yeah.

-Good.

Let's restart those production lines.

Tod's cunning plan is based on a car battery,

electric current and copper wire.

-OK.

-So no copying now.

Oh, wow!

The wire heats up and burns through the sugar.

Brilliant or bonkers?

Bonkers.

If at first you don't succeed, hit it with a hammer.

Yeah, it's not really working, is it?

SHE LAUGHS

Becca and Marty are taking a much more obvious approach,

a big saw.

SHE SCREAMS

Oh, no!

-Oh, no! Oh, no!

-It's cracking.

It's fine, it's fine.

If in doubt eat the mistake, no-one will know.

I'll allow a few extra minutes of production

for Esther and Becca to salvage what they can.

Let's see how well they've done in making the honeycomb centres for their chocolate bars.

Esther, Becca, bring 'em on over.

It's quality control time.

-You're smiling. You're smiling. That's a good thing.

-I am.

Can we actually extract some of the machinery to get to your...

Oh, there is some. Oh, brilliant! OK. OK.

That doesn't look very nice.

OK. So this is real serious quality control here.

THEY LAUGH

Oh, my good...

We're looking for uniformity here.

OK. 11.5, 12.

Esther...

Well, that one's seven.

That one's...

-Shall we taste them?

-Yes.

-What we need is a nice bit of crunch.

Lightness and crunch, I think.

SHE LAUGHS

Oh!

SHE GASPS What went?

It's all right, it wasn't my tooth this time! Crunchy.

Not very airy. But very delicious.

That's not bad. Looks a bit rubbish but not bad.

OK. Becca.

Ah, now you have pulled off something special there.

That does have a lightness that Mum really didn't achieve.

She has overdone the bubble.

I cannot believe you're criticising from there. Look at that!

Now what you need to do is pretty quickly get this honeycomb and enrobe it.

It's got to be covered in a beautiful layer of chocolate.

This is important, not just for the taste,

but because if you don't do it quickly,

this stuff is all going to go very gooey. OK?

Now I hate to sound bossy, but get to work!

HE SCATS

# Mm! Do that again! Bow-bow-bow-bow. #

While Esther and Becca work out how to finish their Crunch 'n' Munch bars

I'm off to discover how to make another melt-in-the-mouth favourite.

I've snuck into the secret research room

here at the Cadbury's chocolate factory in Bourneville.

In here, conditions are perfectly tuned

to concentrate on chocolatey-ness.

My job is to compare two different samples.

Mm-hmm.

OK, that one's much lighter, seems to be much more creamy,

and the chocolate flavour seems to melt really quickly in the mouth.

It floods your mouth with this sensation of chocolate.

So what's the difference between the two samples?

They're both chocolate but they melt differently.

Chocolate boffin Joe O'Shea knows the secret.

That's solid chocolate, you even heard it snap.

So the solid chocolate, when you're tasting it,

it melts very slowly in your mouth.

When you break open the second one you can see that it has

thousands and thousands of little bubbles on the inside.

The bubbles have very, very thin walls,

so when you bite through the bubbles

you get a very fast melt of the chocolate on your tongue.

That's what's unique about this bubbly chocolate.

But how do they get the bubbles into the chocolate?

Can the answer really be outside in the car park?

Come on, you can shake it better than that. Give it some welly!

HE GROANS

Now I want you to go over there, put it on the ground and open it.

-And this is a good idea, is it?

-Yes, it's a good idea.

HE LAUGHS

What you've got here is lemonade, which is water, essentially,

with dissolved gas, carbon dioxide gas inside.

It's already under pressure.

When you shook the bottle you put it under more pressure.

And that is exactly the same principle that we use

to get the bubbles into our chocolate.

Here at the factory, they dissolve carbon dioxide gas in the chocolate.

It makes it fizzy.

So this really is like the bottle of lemonade? It is fizzy chocolate?

What we've got in this pipe is chocolate

with gas dissolved in the chocolate.

It's like opening the bottle, the gas gets released

and you get beautiful bubbles formed in the chocolate.

So if it comes out as basically fizzy chocolate,

why doesn't a bar feel fizzy?

The gas is gone by the time you eat the chocolate.

So what you're feeling is the structure and the lightness that you get from the bubbles.

-Left behind from the fizzy foam.

-Yeah, yeah.

What's left when the chocolate's cooled isn't the carbon dioxide gas,

but the bubble it formed before it escaped.

Like your footprint left in wet sand, the shape is still there

but your foot is long gone.

These bubbles are the reason this chocolate melts faster on your tongue,

so it tastes more chocolatey.

# Bow-bow-bow-bow

# Bow-bow, ooo-ooo-ooo-ooh. #

Back in the barn, I've challenged Esther Rantzen

and her daughter Becca Wilcox

to make two rival Crunch 'n' Munch bars.

Now they've got to cover them in chocolate.

But they must work quickly to keep the crunch in the honeycomb.

Right, so we're about to pour the chocolate into the spray paint guns.

The honeycomb is then going to travel through

-on this little conveyor belt, get sprayed in this box...

-Yeah.

..and hopefully come out covered.

Go into the dry ice box, cool down. At the other end

we quickly pick them up and put them through again on the other side.

-Flip them, to double coat them?

-Well, just to coat the other side.

On a scale of one to ten, how confident are you?

I would say a really good six.

Perhaps Esther's more optimistic?

This is the bottomer, the roller.

Which does the bottom as the name implies.

Very good. Bottom roller.

Meanwhile I'm on the Portaloo pump.

The chocolate goes straight up the tube

and gushes down and this wonderful enrobement happens.

-Fantastic. Are you feeling confident now?

-Totally.

-This is a bit more Heath Robinsony, old-style British engineering.

-Heath Robinsony?

-Yeah.

This is the white heat of honeycomb enrobement.

-Cutting edge.

-Cutting edge.

While Becca and Esther make a few last-minute adjustments,

let's see why it's so important to cover the honeycomb in chocolate.

The chocolate coating on these honeycomb bars is delicious

but it's also there for a very practical reason.

The honeycomb is crunchy

because when it's cooked all the moisture is removed.

The thing is though, this honeycomb wants all of that moisture back.

Normally, if you leave them out,

it will find that moisture in the air around us.

I can show you by using a wallpaper steamer.

This'll speed things up a bit!

It's amazing, it's just disintegrating.

All those little beautiful bubbles...

just turning back into mush.

The only time you want that to happen is when you put one in your mouth

and the saliva all gets sucked up by that honeycomb and melts.

That's why it's vital to get the crunchy honeycomb middle

covered in chocolate, to keep the moisture out.

Becca, Marty, start your production line!

The choco paint sprayers look a bit mad-cap

but this is the method used by the makers of some posh chocolates.

But I'm sure the chocolate should spray onto the bars, not the box!

It's all falling apart at the seams. I'm getting covered in chocolate.

Turn them off!

Terrific!

SHE LAUGHS

Well, some chocolate came out. That's a start.

It just didn't go over the chocolate bar. Oh, it did a bit.

-It's beautiful.

-Look, enrobed.

-That is so funny.

-See?

-What more do you want?

-What a beautiful theory.

Do you think that needs a little bit of tweaking?

-Right, well...

-We're so close.

Esther and Tod want to create a curtain of chocolate.

They hope to rescue their earlier mishap by making bite-size snacks.

Well, your side of the factory is pumped with confidence. Ready?

-Yes.

-Start the production line.

It will be done. The chocolate, Tod.

You can start pumping.

It will be quite hard work, slow and sure.

And here we go, Niagara!

Esther's all pumped up with Tod's chocolate coating machine.

Oh, we're so good at this.

It's completely brilliant!

Can I just say?

I had no confidence in you, Tod, and I was completely wrong!

The bars aren't quite ready to wrap. The chocolate is still too soft.

They need to cool it fast.

Becca and Marty are close to calamity.

Their bars have frozen to their super-cooled box!

-Oops.

-Agh!

Fired up with the success of her chocolate-coating machine,

Esther's hoping to extinguish any chance Becca's bar might be best.

She's spraying frozen carbon dioxide everywhere!

Esther and Becca, your time is nearly up.

Can you please wrap up your honeycomb chocolate bars?

It's time for quality control.

OK. Let's give it a try. So Crunch 'n' Munch.

Oh, it's quite cold inside there.

Oh, my word.

It was looking quite disastrous earlier on,

but I think you've come good. That's not bad.

Oh, that's very sweet, because that looks terrible.

There's an element of rubbish to it, granted,

but these things are difficult to make.

OK. Let's see if it has a crunch to it.

-Argh!

-That's not bad.

-That is not bad.

That's not bad at all. Look at that.

That is not bad.

The question is what does it feel like in the mouth and how does it taste? OK.

-MUMBLES:

-Nearly lost another tooth there.

-Pardon?

He said it was wonderful and it wins.

Quite an even coating of chocolate. Pretty good.

Melts nicely in your hands.

So...Esther's.

SHE LAUGHS

-No, I am...

-And?

-These are really difficult to make.

-That's a much better covering of chocolate than Becca's.

-Thank you.

Pretty good. That's all I'm saying.

Now wish me luck.

THE BAR CRUNCHES

That was a very interesting noise. And still is.

He's learned. He takes it on the back teeth now.

It's delicious. But it's not me that's going to decide.

It's our taste testers. So grab those. Come outside.

Oh, dear.

APPLAUSE

Try this.

Do you happen to have your own teeth...still?

-What do you think?

-Really nice, perfect.

Perfect? Perfect

Harsh on the fillings for the older...

For the older muncher. I suggest sucking the chocolate off?

Sort of sugary, caramelly.

-That's right, yes.

-Is that what you intended?

-Definitely.

Here's something to take the taste away of that disaster earlier on.

I like the chocolate very much. It's good.

-It's actually quite impressive.

-I'm sorry, what did you just say?

-They're actually quite impressive.

-Did we catch that?

Esther, Becca, moment of truth.

What I want here is a show of hands

and what you're judging is not how good it tasted but how close it was

to the chocolate honeycomb bar you'd buy in the shops.

So first of all, a show of hands,

who preferred Esther's honeycomb chocolate bar?

One, two, three, four, five.

Hands up if you preferred Becca's chocolate bar.

Well, I'm really sorry to say it

but, Esther, your chocolate bar is going in the bin.

SHE GROANS

Which means, Becca, your chocolate bar goes in the basket.

Well done! Round of applause, guys.

That was great fun.

Unfortunately Esther didn't get enough bubbles in her honeycomb

but Becca's had the perfect chocolatey crunch.

Now, we all love the sensation

when snack foods magically melt in our mouths,

but as we've discovered, making cheesy puffs

and chocolate honeycomb bars can be really difficult.

Subtitles by Red Bee Media Ltd