Original subtitles

♪ MTV ♪

[upbeat pop-rock music]

We are a nation of snackers.

Over the next 24 hours,

we will get through 1/2 a billion crisps.

- That takes over 17 million potatoes a day

grown and harvested on UK farms like this one in Hampshire.

Tonight, we'll reveal

just what it takes to produce crisps

on such a mind-boggling scale.

As we give you a rare look

inside the largest crisp factory on Earth.

I'm Gregg Wallace.

Bring her in!

And tonight I'll join the race to keep up with demand

for our favorite snack.

That's a packet of crisps?

[laughs]

How does it do it that fast?

I'll meet the supertasters testing every new flavor.

There is a sourness.

What, like curd?

It's a bit like baby sick.

- And reveal the tricks this factory uses

to keep your crisps fresh.

In every bag of crisps is a bag of nitrogen?

I'm Cherry Healey.

That smells really good.

And I'll discover the secrets of the perfect crisp potato.

Why are they so dark?

- Because they have a lot of sugar

which has caramelized.

- And the surprising ways your brain can be tricked

into tasting something that's not there.

It's really tricky.

- I thought I knew a lot about crisps.

- Historian Ruth Goodman uncovers

who really invented the crisp.

- We are gonna have to rethink crisp history.

- I love this! I wanna ride down this in a kayak!

We spend more on crisps than anywhere else in Europe.

- Every day over five million packets of crisps

fly out of this one factory.

It's an incredible feat of logistics and engineering.

- You'll never look at a humble packet of crisps

in the same way again.

- Welcome to "Inside The Factory."

[upbeat music continues]

[word thudding]

[majestic rock music]

- This is Walker's in Leicester,

the biggest crisp factory in the world.

The crisp has gone through something

of a gourmet revolution over the last few years

and you can now get all sorts of posh flavors

from langoustine and lemon

to white Stilton and cranberry relish.

But tonight, we are following the nation's biggest seller,

cheese and onion.

Which is a bit of a disappointment to me

because I'm very much a prawn cocktail man.

More than 40% of the crisps eaten in Britain

come out of this one factory.

It runs around the clock, seven days a week.

But whether they are making ready salted

or something a bit more exotic,

the 24-hour production process begins on the farm

with the right spud.

Almost all crisps produced in the UK

are made with British potatoes.

The most popular varieties are Markies,

Lady Rosetta, and Hermes.

[upbeat music]

The process of making our crisps starts here

on the Hampshire potato farm of Gavin Janaway

whose family have been growing crisp spuds since the 1970s.

These will be going to the crisp factory

later on today.

- Have they just been dug or have they been in store?

- No, these have been in store now

for about six months.

- We keep them at the right temperature,

the right humidity with fresh air going in there

because a potato is a living, breathing thing.

You know, we've gotta try

and keep it happy and keep it warm

so it produces a good crisp.

- How do you know when they're growing in the ground

that they are gonna be perfect for the crisp?

You can't tell.

- Well, to try and help us tell, Gregg,

we've got our own little frying facility on-site here,

our little potato lab.

And we take samples from the field

throughout the growing season

and throughout the storage season

and we take them through there and we test them

and we actually fry them ourselves.

So, I do my own little "MasterChef,"

a little cooking myself, a little bit of salt and pepper,

just the right seasoning.

We test them to make sure they're right for the factory.

If they're not ready when we fry them at the field,

we just give them another couple of weeks

and a bit of sunshine and everything

will help them mature.

[bouncy upbeat music]

- At any one time, Gavin could be storing as many

as 160 million potatoes on his farm.

When they get the order through from the factory,

the potatoes are fed into one end of a production line

which can sort, wash, and load 27 tons of spuds

onto a truck in less than 45 minutes.

[potatoes clattering]

Here we go. A nice big crate of British spuds.

How long before that lovely spud

becomes a cheese and onion crisp?

- That could be a cheese and onion crisp

within six hours.

[upbeat indie-rock music]

- This is where our crisp production line starts.

So, we're now just looking for anything that's green

or has got damage on it or maybe a little shoot on it,

anything that may affect the quality.

- So, take the sprouts off. - Something like this.

This is damage that's been done through harvesting,

so that's mechanical damage, that comes out.

- There's another one. - That comes out.

Yeah, you won't beat him, he's too quick.

He's the fastest one here. Nobody beats Gregosh.

It doesn't surprise me

the best one here is called Greg.

[Gavin laughs]

How often are you set up like this?

- This is set up all year round.

So we load any day of the week all year round.

- Hey, a green one! I got that before Gregosh.

How many potatoes on a lorry load?

There's 27 tons.

So I think that works out

roughly 200,000 of packets of crisp

in one lorry load.

How many lorries go out?

- A busy day would be 10 lorries.

So that means on a busy day

you send out two million bags of crisps.

Yeah.

[potatoes clattering]

[forklift beeping]

[upbeat indie-rock music]

Have to admit,

I find potato shopping a little bit daunting.

There are so many different varieties

and I never know which one to buy.

In fact, there are more than 230 varieties

of potato grown in the UK.

About half of those will end up in your produce aisle

but the other varieties

are used to make everything from frozen waffles to vodka.

But which variety makes the perfect crisps?

To find out, I'm heading to potato HQ,

the National Agronomy Center in Cambridge,

where James Fowler is a spud expert.

- Ready to go in? - It's ready to go.

Here we go.

- We're going to have a crisp fry up

but with three very different varieties of potato.

I've brought some Maris Peers,

a waxy new potato great for salads,

some King Edwards,

a more floury potato perfect for mashing,

and James has got this one.

You won't have seen this one,

Cherry, it's a specialist crisping variety

we're investigating at the moment.

We think it's gonna make good crisps.

- It's brand-new? - Yeah.

It's a revolutionary potato.

The first obvious difference is the shape.

Crisping varieties should be predominantly round.

Not long like this Maris Peer.

If they're too small, the crisps are too small

and the bags look half empty

and also there's a lot more peeling waste

when you process them.

[upbeat pop music]

- But the differences are more than skin deep.

When it comes to making crisps,

there are three key parts of a potato,

water, which makes up about 80% of the average spud,

starch, and tiny amounts of natural sugar.

Using a hydrometer, you can tell how much water there is.

My two potatoes are about 80% water

but a good crisp potato has only 75%.

The less water, the better

because you need to get rid of almost all of it

to make a crisp.

Now the fun bit.

Now we fry all three potatoes in exactly the same way.

The water is boiling off.

- And that's what's causing all this steam?

That's right.

- If there's more water in a potato

when it goes to the factory, you get more steam.

And fewer crisps.

- That's not what you want if you're making crisps.

But when it comes to making light, golden crisps

on an industrial scale, the biggest enemy is sugar.

Wow.

Why are they so dark?

- Because they have a lot of sugar

which has caramelized and produced the dark color.

- The King Edwards have less sugar

and so are noticeably lighter.

Finally, we fry the specialist crisp potatoes

at the same temperature as the other two.

Not only do they cook much faster,

they look completely different.

- They look better. - Wow!

So those are much more familiar.

- Well, less sugar. - Less sugar.

- Less sugar, there's no color development.

- The subtle differences of potatoes

might not matter much

if you're just having a fry up at home

but for the nation's biggest crisp makers

making tens of millions of them every day,

the science of spuds is everything.

[munching] Mmm!

[upbeat electro-rock music]

Yeah!

Come on, bring her in!

How many potatoes have we got on there, do you know?

- There's about 200,000 potatoes on average.

- And how many trucks like that come in every day?

- We get about 25 every single day,

24 hours a day.

So, that's about five million potatoes every day.

How many potatoes

in one standard packet of crisps?

- Well, we're using about five million potatoes every day

and we're making about five million packets every day.

That's a packet of crisps?

Dead right.

- I love this. I absolutely love it.

Potatoes are much more delicate than they might seem

and can easily bruise.

So, the best way to get 200,000 spuds off a lorry?

Float them off.

Fire her up! Let's go!

[water rushing]

Yay!

That's a fair amount of water there, old son.

They basically flood the compartment of the truck

and the potatoes just come out with the water.

Exactly right.

But that now is a very wet potato.

I mean, that is gonna start to deteriorate.

You can't keep potatoes in water.

- No, so, time is of the essence but in 35 minutes,

it's gonna be in a packet of crisps.

- Just over half an hour and you turn that into crisps.

I can't make chips in that time.

[water splashing]

[upbeat pop-rock music]

[potatoes rattling]

When you're dealing with five million potatoes a day,

you need an efficient way of peeling them.

And here, in the world's biggest crisp factory,

they have to peel more than 2,000 every minute.

To do that, you need some hardcore potato peelers.

[potatoes whooshing]

- We're using a thing called abrasion peeling here.

Something that your grandma

actually might've had in her kitchen.

We're spinning the potatoes round against a rough surface,

a little bit like sandpaper,

and just removing a small amount of that peel

to leave a clean potato ready for the next process.

- That's quite an aggressive rumble.

You cannot only see it, you can feel it under your feet.

How do you know you've peeled them all properly?

Because even if I do half a bag of potatoes,

sometimes I might miss a bit.

- We've got a whole series of digital cameras here

and they are looking at every single potato.

- It photographs every single one?

Every single one.

To the side here, you can see what looks a little bit like

a piano keyboard, a series of fingers.

If we get a bad potato coming through,

you'll hear a gust of air

[machine thuds]

and that will kick that potato out,

that will be rejected.

That's a bit nuts, mate.

[machine thuds]

[laughs] How does it do it that fast?

[machine thuds]

My potato is about to be sliced and fried

and turned into a crisp.

A process that will be repeated five million times today.

But who first did it? Who invented the crisp?

That's a question Ruth Goodman's trying to answer.

And it's not as simple as it sounds.

- [gentle upbeat music] - [birds chirping]

If you speak to Americans,

they will tell you that they invented the crisp in 1853.

And that it's down to a man called George Crum,

a chef who was working in a country club

in New York state.

The story goes that the chef Crum

had a particularly difficult customer,

a wealthy industrialist,

who kept sending his chips back saying they weren't thin enough.

George got so fed up in the end

that he decided to make the chips

so thin that they would be inedible

and then he covered them in salt.

Much to his surprise, the customer loved them.

So much so, that he put them on the menu.

But for me, there's something fishy about this story.

We've been cooking potatoes for 200 years

before the Americans claimed to have invented the crisp.

Surely we'd come up with a similar recipe before then.

[gentle rock music]

To get to the bottom of this mystery

and find out once and for all who invented the crisp,

I'm meeting food historian Regina Sexton

to plot the history of the humble crisp.

- The potato is in England by the 1580s, the 1590s,

is looked upon as an exotic thing.

So, it's something desirable,

a plant for people to have in their gardens.

Gradually, potatoes

moved from being just a specimen plant

to become something that we started to eat

and by the 18th century,

they had become the staple of the Irish poor.

Soon they were eating an astonishing

12 to 14 pounds per person per day.

I can hardly even lift that.

That is a huge amount of potato.

It is.

But that's it.

That's the only thing you eat all day?

Yeah.

- As Britain's population exploded in the 19th century,

the potato became a culinary mainstay.

One of the most popular Victorian cookery books

was William Kitchener's "The Cook's Oracle,"

first published in 1817.

- This book, in fact, was a bestseller in its day.

- Really? - I love this.

"The vegetable kingdom affords no food more wholesome,

"more easily procured, easily prepared

"or less expensive than the potato."

- It's packed with potato recipes

including one that's quite familiar.

"Potatoes fried in slices or shavings."

- Now, that's a really interesting recipe

if you read through it.

"Fry them in lard or dripping

"and keep moving them until they are crisp."

Crisp.

- What date did you say this was?

- 1817. - 1817.

So, that's quite a bit before 1853

when the Americans say

they invented the crisp, isn't it?

Yes, it is.

So, if we cook this

and it really turns out to be a crisp,

then we are gonna have to rethink crisp history.

I think we might have to.

[upbeat folk-rock music]

The only way to find out

if this really is the very first recipe for crisps,

36 years before it was claimed

that George Crumb invented them in America,

is to try out the recipe for ourselves.

So, "Peel large potatoes.

"Cut it into little slices about 1/4 of an inch thick."

- Lard to go in there. - Yeah.

- "Put it on a quick fire." A fairly hot fire.

They look like they're cooking nice.

They've gone pale, they're rising to the top.

- Excellent. - Bubbling like crazy.

- "Keep moving them till they are crisp."

- Oh, that's puffing up a little bit there.

Smells lovely.

- "Take them up and let them drain in your sieve."

Okay. "A very little salt sprinkled over them."

Yeah.

- They smell like crisps, don't they?

- They do, yeah. - [laughing]

More salt. [munching]

It looks like a crisp. It smells like a crisp.

It tastes like a crisp. That is a crisp.

So, would you say that the invention of the crisp

is definitely before the American story?

Certainly.

If you do this recipe,

you produce fried slices of potatoes

that are certainly crisp.

- So it looks like us Brits really did invent the crisp.

[upbeat pop music]

- Back at our factory in Leicester,

our potatoes have been cleaned and peeled

and are now heading for the knife.

The first step is to make sure they're all the right size.

So, what we've got here are our potatoes

and they're getting presented

across the top of this screw deck.

And as you can see,

the smaller ones are falling through,

they don't need cutting, they're already the right size.

But there's a few that are coming through.

They're a little bit bigger

and they are heading for the guillotine.

So, we're gonna cut those potatoes in half.

- So the French peasant small potatoes

are falling through the holes,

the aristocracy is going across the top here

to meet Madame Guillotine.

Can you tell in a bag of crisps

whether you have got crisps that come from a hole

or a cut potato?

- I'm gonna let you into a secret,

which is if you look at those crisps,

if it's got a straight edge,

it's been halved on a machine like this.

- I'll have a look when I get home.

Very good.

- So, now we've got the right size,

are they gonna be sliced?

We're ready to slice.

How long have you got left?

You've got about 20 odd minutes left.

[upbeat pop-rock music]

Next, my spuds take the conveyor belt

up to some of the fastest potato slicers on Earth.

Inside these machines, there is a drum

spinning at very high speed.

When the potatoes are dropped into the drum,

the centrifugal force flings them to the outside

where an average potato is cut into 45 slices

in around 0.2 of a second.

Wow!

That's unbelievable!

It's all done by eight hardened steel razor blades

which constantly need changing

and that job falls to Sudhir Raval.

That's incredibly ingenious.

As that spins really fast, the potatoes...

But they stay on the outside of the drum.

That's right.

And as they turn round, they... Wow!

There are 33 slicers throughout this factory

and they get through almost 2,000 blades every day.

You never actually touch the blade,

you use the magnet.

I wanna be the razor blade salesman here.

[upbeat pop-rock music]

Can I check my slices?

- Yes, we can do. - I've done a good job there.

The slices are constantly checked

to make sure they're being cut

to precisely the right thickness.

[upbeat rock music]

Then they're off.

Racing down a giant river of potato.

[water rushing]

I love this. I wanna ride down this in a kayak.

- Now, the water you can see here is milky

and that's because it contains starch.

The starch has come out of the action

of cutting the slice.

Water taking the starch out.

Another spray of water to wash more starch out,

another bath to get the starch out,

and another spray.

And that is to stop them being so starchy

that they stick together as a clump.

Is that right?

Absolutely right.

- I can guarantee they're the right thickness.

I've been up there changing the blades and measuring them.

What you can see here, they go through the hairdryer

and what we are looking for

is we talk about the slices dancing a little bit.

So they're bouncing around

and that means there's just the right amount of air pressure

to just dry that slice out just enough.

- Now my slices are ready to be fried.

The factory has seven mammoth industrial fryers

running 24 hours a day.

They're filled with a blend of rapeseed oil

and sunflower oil trucked in from southern Europe.

All major crisp manufacturers in the UK

now use sunflower oil instead of traditional cooking oil

as it contains less saturated fat.

What temperature? Am I allowed to ask?

So, it's around 180 degrees C

but we'll move that up a little bit

and down a little bit according to the potato.

So, we'll make adjustments to the temperature

and also to the time.

It's around three minutes

but we'll adjust it according to the product.

- So, those potatoes, that I watched come in,

you will adjust the temperature

to cook those differently to the others?

Exactly right.

As they fry,

the water inside our potato slices is boiled off

and replaced with some of that oil.

An individual bag of crisps

has just over 1/2 a tablespoon of oil in it,

which means these fryers are getting through

tens of thousands of liters of oil a day

and need to be topped up continuously.

That is the most crisps I have ever seen in one place

and I've been to a few parties.

These haven't got a flavor on yet, have they?

- Nothing. - No. Nothing at all.

This is pure unadulterated crisp.

- I've never had a pure unadulterated crisp.

- Would you like to go fishing for crisps?

I'm gonna test your knowledge.

What's special about that crisp?

Oh! That's been cut.

Yes!

You've been paying attention.

Hot crisps.

You've never tasted better.

Lovely crunch.

Needs a little bit of salt, mate.

I don't suppose you've thought of that.

[upbeat indie-rock music]

Back in Leicester,

we're a little over four hours into the process.

My crisps have just come out of the fryer

and before they can be seasoned,

they have to be inspected.

Every single one of them.

Tell me how you can look at every single crisp.

- Inside here you can see the bright light

and we have a digital camera

which is inspecting every single crisp

- passing the crossing. - How fast is that going?

- That machine is handling 450 crisps every second.

And then the machine is making a decision to say,

"Yes, it's good," or, "No, I'm gonna reject it."

It's using a fine jet of compressed air.

Hang on, hang on, hang on!

At 450 crisps a second,

the machine is taking photographs

and then directing a jet of air

to knock them off the production line?

Exactly right.

I can see the crisps dropping

but they look like they're just falling.

They're actually being knocked off

by a computer-directed jet of air.

That's James Bond, that is.

And there's an evil genius sitting somewhere

that devises all this?

Is he's stroking a white cat?

[Simon laughs]

So, this is all about color.

So, it's looking for a color

that you wouldn't want in the bag.

As Cherry discovered earlier,

if a potato contains too much sugar,

that sugar will caramelize as it's fried

giving the crisps a brown color.

But it's kind of not fair, is it?

Because some farmers' batch of potatoes

might have less reject crisps than others

or am I getting, like, too pernickety?

- Well, we would love all our farmers

to produce great quality

so we recognize that.

So, for the best potatoes, we pay a quality bonus.

- So every batch of potatoes that come in, mine as well,

all right, everybody gets it,

the farmer knows what he's gonna get.

But if they get less rejects, they get a bit more?

- Exactly. Because we're making a few more bags of crisps.

- I bet mine were perfect. You can pay me in cash.

[Simon laughs]

[upbeat indie-rock music]

My potato slices have been dried, fried, and scrutinized

and now they're finally ready to be flavored.

They travel on a system of vibrating conveyors,

which is the only way to move crisps quickly

without breaking them,

and eventually arrive at one of 23 giant seasoning drums.

Welcome to seasoning.

- That aroma is instantly recognizable

to anyone who's ever opened a bag

of cheese and onion crisps.

That's quite incredible.

What's happening exactly?

- What you can see before you is this drum

and what we're using the drum to do

is to gently tumble those crisps

so that we get a perfect coating of the seasoning

on both sides of the crisp.

You can see behind, we've got a powder.

So we're dropping it, sprinkling it across the crisp.

- So, when I open a packet of crisps,

what percentage of it now is potato

and what percentage is seasoning?

What's the ratio?

- Yeah, well, in the case of cheese and onion,

we put about 6% of cheese

and onion seasoning on our crisps.

- I love the fact... Can you kneel a little bit?

'Cause I like having my crisps served on a silver tray,

still warm.

That's a flavor and a texture

that I've actually grown up with.

You know what I fancy now though, don't you?

Is a pint of beer.

[Simon laughs]

The time between now

and getting them in a bag must be crucial.

Absolutely.

So, from here to a bag is only about three minutes.

It's a crisp superhighway, isn't it?

[upbeat indie-rock music]

They get through more than 450 boxes of seasoning

every day in this place.

It's all made off-site by large seasoning houses.

But what surprised me is that almost every new crisp flavor

this factory comes up with starts off as a real dish,

cooked by a real chef here in the factory.

Ben Barlow is in charge of the development kitchen.

He's invited me in to taste some of the dishes

his team are cooking up

as they develop new crisp flavors.

- A lot of the flavor actually is the batter.

I'm helping him develop

a new cheesy beans on toast flavor.

Make one that you wanna eat

and I'll make one that I think the public will wanna eat.

- All right. What are they, chef?

They are homemade ones.

I wanna put a little bit of Parmigiano on it.

It can take over a year to develop

and launch a new flavor.

It all starts with Ben and his team

cooking up dozens,

sometimes hundreds, of variations

and then trying to identify the subtle flavor difference

in each one.

Here we go. So this is ours.

We start breaking it down, and that's what we do here.

We break it down into each of its taste components

and then try and recreate that on a crisp.

Actually, start thinking about cheesy beans on toast,

it's quite complex.

Just describe to me the flavor journey.

So, what are you getting first?

What's starting to come through second?

For me, first of all,

the unmistakable smokiness of paprika.

Then, after that, straightaway we're into the fruity richness,

almost sweetness, of the beans.

Yours did have a cheese flavor, mine didn't.

Once Ben's decided

which version of cheesy beans on toast is right,

he then needs to have that flavor produced

on an industrial scale

by Europe's largest seasoning houses.

But first, he has to describe the specific taste

he wants them to create.

- I wanna say, "Right, I wanna taste the beans first,

"I then want some toast and butter coming through,

"and then I want it to finish with cheese."

[gentle pensive music]

At the seasoning house,

a team of food scientists use a complex combination

of mainly natural and some processed ingredients

to match the flavor Ben's described.

Once they've got it right,

it's produced in vast quantities

in 2 1/2 ton mixers and trucked back to the factory

where, in total, they get through more than

10 tons of seasoning a day.

But before Ben's new flavors get anywhere near the public,

they have to get past a panel of supertasters.

- So, if we taste sample E again.

- Cheese note there, isn't there?

- Yeah. - Feels like black pepper.

- There's no burn, is there? - That's quite smoky.

- Every day, a group of hand-picked

specialist crisp tasters meet to sample new flavors

and check the existing ones are up to scratch.

Hello, guys.

- Hi, there. - Mind if I join you?

- Not at all. - What are we doing?

- We are looking at developing a new flavor today.

R&D want some feedback, so let's get straight into it.

If we taste sample A first.

Getting quite a strong tangy note.

- Cheese. - Perhaps cheese.

That's definitely cheese,

but that's quite mild

and it hasn't got the tang of a cheddar.

- Okay, so, what are the key differences

between samples A and B?

- Heat. - Heat and spices.

- You're right, it's got a spice finish.

Stays on your tongue.

- There is a sourness, isn't there?

- A dairy sourness - A dairy sour.

What, like curd?

- It's a bit like baby sick. That butyric acid sort of thing.

- Well, either you've tasted baby sick

or you were a baby a little while ago.

I mean, I don't know how you're getting that.

[upbeat music]

Any new flavor, even a new potato variety,

has got to get the okay from this team

before it goes any further.

So, there are some very influential

tongues in this room.

Is this your job?

This is my only job, yeah.

- And are you proud when you go to a party

and people wanna know what you do?

- I am very proud, yes. - [all laughing]

- Is there any chance your palates

can kind of, like, run out?

- Yeah, I think as you get older--

Can change.

- Your taste buds change, definitely.

- So, the guys are monitored constantly to make sure

that they can still taste at the highest possible level.

Thanks for your years of service,

but I'm afraid your palate is all washed out.

We've got you a watch.

[all laughing]

We were gonna have a party, but what's the point?

You can't taste the food.

These professional tasters are able to identify

the most subtle of flavors,

but, as Cherry is discovering, our experience of food

depends on a lot more than just taste.

- [birds cawing] - [upbeat pop-rock music]

- Have you ever wondered why fish and chips

taste so much better by the seaside,

why a whisky always tastes better by the fire,

or why wine you drink in France just doesn't taste as good

when you get home?

Charles Spence is professor of experimental psychology

at Oxford University

and his research has helped uncover the answers.

I'm hoping you can tell me why fish and chips

taste so much better by the seaside.

Our brain, all the time,

is picking up information from around us

and using it to infer what we think we're tasting

and how much we think we're enjoying it.

So, if we're eating those fish and chips by the seaside,

then you would imagine

there's the smell of the salty sea air,

maybe the sound of the seagulls.

Making the leap that the sea is just there,

that fish is fresher.

It's all really happening up here in our head.

And as your brain combines all the senses

and glues them together

in ways that the science is just starting to reveal.

[upbeat electro-pop music]

- Professor Spence uses innovative lab experiments

to investigate just how our taste is influenced and confused

by our other senses.

Now we are going to test them out

in the real world

to find out what happens when we eat crisps.

Here, in the pubs of Brighton,

we've got no shortage of unsuspecting subjects.

Would you do us a massive favor and eat crisps?

Yeah.

- First, we're going to take away

people's sense of smell

to see if they can still identify the flavor

of a beef crisp.

Can you smell anything?

Can you give me a... [sniffing]

- I can't open my nose. - Nose at all. Perfect.

What flavor do you think they are?

It's really tricky.

[Charles laughing]

Are they a bit oniony?

This is so weird.

[upbeat electro-pop music]

- What would you say the flavor was?

Maybe bacon, I think.

I'd say chicken.

Cheesy, cheese and onion.

- It tastes just like cardboard, no taste.

Take your nose clip off.

I know, it's beef and onion.

- Can you tell the real flavor is?

It tastes beefy.

- Beef, roast beef. - Yes!

So, did you notice a significant change

after you could smell?

- Yeah, it was completely different, yes.

- No one we asked could determine the flavor,

proof that smell is fundamental to taste.

- We think we're tasting things,

we experience the taste of the crisp in our mouth,

but, in fact, maybe as much as 75% to 95%

of what we think we're tasting is really coming from the nose.

Every time you swallow,

a little bit of the volatile aromas

that we've made in our mouth

are kind of pushed out of the back of the nose.

[sniffing]

And that is what we think of as taste

but it's really smell.

[upbeat indie-rock music]

- The next surprising experiment aims to show

that our enjoyment of crisps

can be somehow influenced by what we hear.

- Gonna get you to put some headphones on.

- Can we convince people that identical crisps

have different crunchiness?

- Close your eyes and put your hand out

and we'll give you the first one.

- They need to rate the crunchiness

on a scale of one to 100.

- 60, maybe. - 60? 50?

- On the second identical crisp,

Professor Spence now uses a computer

to increase the volume

of the high-pitched sounds in the crisps crunch

being fed into the headphones.

- I think crunchier. - Crunchier.

How much crunchier?

Hmm, quite a bit.

So maybe a 90.

- That's crispier, I think. About 90.

90?

- 90. - 90.

Like, an 80 or 90.

- Ooh. Okay. - So significantly crispier.

- Are you surprised to know that both of those crisps

are from the same packet, both exactly the same freshness?

- I thought I knew a lot about crisps

but obviously not.

[laughs]

- Professor Spence's studies show on average

subjects believe it's around 15% crunchier

when the sound is manipulated.

It did make a big difference.

- The noise crisps make when you eat them

gives our brain information.

Subconsciously we associate the crispier crisps

with being more appetizing.

Think we're tasting the crunchiness

between our teeth and in our mouth,

but in fact, all the time,

our brain is picking up the sounds of crunch or crackle

and those sounds are very informative

about what we're actually tasting.

Every time we crunch into something,

our ears hear those sounds,

and depending on the frequency spectrum,

how loud the crunch,

we use that to infer how crisp, how fresh the food is.

- From these experiments, it's clear that smell

and sound are critical to our taste.

So, next time you eat a crisp,

stop to think about how many different senses

are influencing your enjoyment of it.

Or not. You gave me a stale one.

[upbeat music]

[upbeat folk-rock music]

- It's been less than 4 1/2 hours

since my potatoes were sitting on the farm in Hampshire.

They've been peeled, fried, seasoned,

and now they just need to go in a bag,

which presents the next challenge for this factory.

How do you fill a bag with an exact weight

when no two crisps are identical?

The answer lies in one of the craziest rooms I've seen.

[upbeat whimsical music]

Julie Biddles is responsible for filling

hundreds of thousands of bags of crisps an hour.

This is quite an extraordinary room.

Yeah. Very good, isn't it?

- I don't think anybody ever would have seen

anything quite like it, ever.

How many of these things are there in here?

There's 118.

118 of these individual...

And tell me, is each one of these little buckets

with the numbers on, is each one of these a bag of crisps?

No.

It's a weighing machine and it will use

three to four combinations to make one bag

but you might have a little bit in each one

to make up the 25 grams.

- Inside this little bucket now it's being weighed

and then a computer will choose a combination

of four of these to make up one bag.

- Whichever the best combination is to make that weight.

- And the computer will quickly add up

how many of those buckets makes a 25-gram bag

and shoot them down.

- 30 milliseconds it takes to calculate the weight

and then it will drop it.

- Every time we hear a click, that's another bag of crisps.

That's a bag.

[upbeat whimsical music]

- And people must be eating them

at the same pace as you're making them.

So, every second, a bag of crisps is being eaten.

[machinery whirring]

- 24 hours a day, seven days a week.

- We are a serious nation of crisp munchers, aren't we?

[upbeat indie-rock music]

The instant they are weighed,

the crisps drop through the bottom of the machines

into waiting bags below

and it's all happening hundreds of times a second.

[upbeat indie-rock music]

I wouldn't have believed this was possible

if I hadn't seen it myself, but less than 30 minutes

since my potatoes were sitting on the back of a truck,

they're now crisps in a bag.

But before that bag is sealed,

there's one last surprising thing to be added.

So, is that air you've pumped into there then?

- What we've got inside the bag there is nitrogen.

- That keeps it fresh. - Really?

- There's two main constituents of air.

One is oxygen, fantastic, it keeps you alive,

but it's the enemy of food.

It would make our crisps go stale.

The other thing, which is the majority of air,

is a thing called nitrogen.

We put nitrogen in the bag

and that's the reason you get that fresh taste

every time you open a packet.

- Every bag of crisps is a bag of nitrogen, is that right?

- It's a bag of crisps full of nitrogen.

- I'm taking for granted that's safe, right?

- Perfectly safe. It's all around us.

- So, oxygen deteriorates food, right? I get that.

Got it.

But nitrogen doesn't,

it will kind of keep it in suspended animation.

- Stable, yeah. It preserves it for longer.

- What would happen if you didn't flush nitrogen through?

What would happen, do you think, if you just flushed air into it?

To try and answer this question,

Simon's got two bags of crisps, both three months old.

- Do you think I will know the difference?

One is a standard bag that was filled with nitrogen

and the other was filled with normal air

to see if I can spot the difference.

[gentle rock music]

There's not a great deal of discernible difference.

- The best way to tell is using your nose.

- There's a difference. - There's a difference.

- Much. There's a difference in the smell, most certainly.

That, actually, that one does smell of oil.

[Simon chuckles]

And that one smells of cheese and onion.

But they're both crisp.

I mean, they're both crisp and they both taste okay.

But I'll give you it, that one smells of oil.

Well, we're passionate about crisps.

We notice the difference

and we care about the difference.

[upbeat indie-rock music]

- As well as helping to preserve the crisps,

the nitrogen also acts as a cushion

to protect them on their journey to the shop's shelf.

It's been less than 4 1/2 hours

since I saw the spuds being loaded into a truck

and now my crisps are heading for distribution.

They've got to move more than five million bags of crisps

all over this gigantic site every day,

so forget about conveyor belts.

[upbeat electro-rock music]

Welcome to the crisp monorail.

This computer-controlled system snakes through

the factory's distribution center

connecting the packing hall with the loading bay.

The distribution center is monstrous,

more than 37,000 square meters,

larger than the Houses of Parliament.

And from the control room,

Chris Neville can track every single packet.

From this nerve center here,

we can see all the pallets moving around the site,

which ones are going to which customers,

and we can also track the vehicles.

This truck is going to a customer

and do you see the blue arrows?

It should arrive in about 40 minutes.

- The trucks not only deliver crisps to supermarkets,

many will also then collect potatoes

on the way back to the factory

and Chris knows where they are at every stage.

So just take a potato, right?

One potato.

From the moment it leaves that farm's gate,

all the way down to here,

and then through every process

and then back out again as a cooked and flavored crisp,

all the way out to the shop where I can buy it,

you track it minute by minute.

Correct, yes.

George Orwell predicted this.

[majestic rock music]

On average, a truck loaded with crisps

will leave this distribution center

every six minutes.

From the factory in Leicester,

they'll be delivered all over the UK,

where the biggest crisp eaters are in the northeast.

And amazingly,

some will even make it to the Costa del Sol

to satisfy the ex-pat market.

Raw potatoes that were on a farm just this morning

could be being eaten as crisps as soon as tomorrow.

It is quite remarkable

that you can put a simple potato in one end of a factory

and it'll come out as a sealed, flavored bag of crisps

the other end of the factory in just 35 minutes.

Not only that,

the engineering and the precision

that you need to do it five million times a day.

But do you know what really surprises me?

It's that we actually eat that many crisps.

Right, I've done my training,

the only thing left is to load my crisps

on the back of a truck.

Chocks away, Ginger!

[majestic rock music continues]