Original subtitles

Ooh, look at this, absolutely handsome.

I love a Yorkshire pudding with my roast beef on a Sunday.

Excuse me.

And I love them too,

but mine never seem to turn out quite how I was expecting.

Come on, Cherry, you didn't actually think I made these, did you?

Delicious, chewy and crunchy,

Yorkies are a great British tradition.

And every year, we Brits buy more than 500 million

of these little frozen batter puddings.

And this is the best place to find out how this Sunday staple is made.

A 9.5-acre site dedicated to Yorkshire pudding production.

What an earth is that?

I'm Gregg Wallace...

Yay!

..and tonight, I'll be following the recipe...

I'm never this precise at home.

..and learning some cold, hard facts...

Woo-hoo-hoo. What you got is a merry go round for Yorkies.

..to find out how technology transforms five simple ingredients

into the perfect pudding.

I'm Cherry Healey,

and I'm learning how to make the perfect gravy.

And putting flour through quality control.

So, actually, it's thanks to these silos

that my family can have Yorkshire puddings on a Sunday.

And historian Ruth Goodman...

That looks so delicious.

..is discovering how roast beef

became part of our national identity.

When the French call us Les Rosbifs,

they don't mean it as a good thing,

they mean it as an insult, don't they?

They make a staggering 500 million Yorkshire puddings here every year,

and I'm going to find out just how they do it.

Welcome to Inside The Factory.

This is the Aunt Bessie's factory in Hull.

They've been making Yorkshire puddings here for nearly 30 years.

The 450-strong team also produces traditional goodies

like sponge puds, fruit pies and jam roly-poly.

Mm!

But today I'm learning how they make one of their bestsellers -

the frozen pack of 2½-inch glorious golden Yorkshires.

Yorkies are the heart and soul of the best meal of the week.

For me, they're the cornerstone of a great Sunday roast dinner.

And in tribute to this proud British tradition,

I'm starting in the traditional way - at the intake bay,

where I'm meeting Materials Manager Chris Laws

Hello, Chris. Hey.

Nice to meet you, Gregg. I don't want to get in your way, mate.

No, you're fine. Busy man.

Right. All starts here. Yeah.

Goods in. Intake, start of the process. What have we got?

We've got a 24-tonne tanker of flour.

What flour have you got in here?

Our flour actually classifies under the biscuit variety.

You've got cake flours, bread flours

and a biscuit flour sort of falls in the middle of them both.

What's particularly different from a biscuit flour than a bread flour?

A bread flour would be a lot higher in protein,

so it would naturally contain a lot more gluten.

You want less gluten?

Yeah. We need gluten for structure,

but not as much as a bread flour would be.

Right, OK. Do you want to see a sample?

Yes, please, please.

Is this honestly the flour that people would make biscuits with?

Yeah, yeah. Yeah.

That's where it gets its name from in the industry.

In milling terms, it's determined by protein level

and the variety of wheat the flour miller would make it from.

So it's soft wheats.

It's called biscuit flour, but it isn't sweet,

it's all about the texture when it bakes,

and soft wheat flour has the lower gluten content

needed to make good Yorkies.

I'm not sure we can buy biscuit flour in the supermarket,

so what's the closest to this?

The most comparable flour would be like a plain or all-purpose flour.

How much have we got on here? 24 tonne.

Roughly, how many Yorkies are you expecting to make with that?

Hopefully about 3.3 million Wow!

It's a lot, Gregg. That pleases me.

How do we get production started?

We need to unload this 24-tonne tanker, Gregg.

Come on, come on.

It'll take over an hour to pump the flour into this 40-tonne silo,

where it'll be kept till it's needed on the production line.

So, as I open the valve...

Yay!

..my Yorkshire pudding production begins.

They don't use any old wheat to make flour

that's good enough for Yorkshire puddings.

But how do you test its quality?

Cherry has been finding out.

CHERRY: In the UK we grow over 90% of the wheat we need,

with farmers harvesting around 14 million tonnes every summer.

But the quality can vary wildly,

depending on factors like the soil, pests and the weather.

To make exceptionally good Yorkies, you need exceptionally good wheat.

But how on earth do you know if your wheat is up to the job?

To investigate, I'm visiting one of the country's

biggest wheat stores.

Woldgrain in Lincolnshire.

During each summer's harvest, wheat is brought here

from farms up to 70 miles away, to be graded and stored.

Its manager is Dan Murphy.

Dan, I've seen some silos in my time,

but never this amount of silos.

I mean, you're like a silo breeding farm.

Yes, we have 60 silos,

and our total site capacity is 100,000 tonnes of grain.

What kind of wheat do you store here?

We store hard wheat and soft wheat.

At the factory, Gregg's taken a delivery of soft wheat flour for

his Yorkshire puddings, which comes in lots of different varieties.

The varieties of wheat have names given to them by the breeders. OK.

For example, Skyscraper, Illicit, Astronomer, Firefly.

And a truck full of Skyscraper has just arrived.

But before any delivery can be unloaded, it's tested to

establish the quality of the flour it will eventually produce.

So, first, our soft wheat sample is ground into flour.

Fill it up to the top? Yes.

OK.

Oh!

The flour from the Skyscraper wheat should be

suitable for the Yorkshire pudding factory, if it passes Dan's test.

There we go. Ooh, it's lovely and warm. Mm.

If it fails, it'll only be good for animal feed,

which means the farmer will be paid less for it.

We need to test that flour for something called alpha-amylase.

What on earth is alpha-amylase?

Alpha-amylase is an enzyme that turns the starches

within the flour into sugar.

This reaction is only triggered when wheat gets wet and germinates, which

is why it's vital that it's kept dry during and after the harvest.

We need starchy flour to give our Yorkshire puddings structure,

so every grain delivery must be checked.

We're mixing the flour sample with water to create a kind of batter.

Then you give it a really good shake.

I used to work in a bar. It's fine, I got this.

We're also testing an earlier delivery, to see which would

make the better Yorkshire puds.

Mine's the one on the left.

And then the whole lot goes into the Hagberg machine.

What is a Hagberg?

Well, the test was invented by a man called Mr Hagberg

from Sweden in the 1950s.

The machine tests whether the alpha-amylase

has affected starch levels in the flour.

It heats the mixture in the tube,

causing the starch molecules to absorb water and swell.

Then the plunger is allowed to fall through the dough just through

gravity, which then tells us the amount of starch left in the flour.

The more starch in the dough, the thicker it is,

and the slower the plunger will fall.

What do these numbers mean?

So, this is the Hagberg falling number.

It is literally the number of seconds it takes for the plunger

to fall through the dough.

Does my sample pass the test? My sample is 247.

We are looking for a falling number of over 200.

247, that is an ideal result for a soft wheat.

So, the other test tube got 86. What does that mean?

Yes, that wheat would only be suitable for animal feed.

My sample of Skyscraper has passed the test,

which means this load of wheat is the right stuff

for making the perfect Yorkshire pud.

And the lorry can be unloaded

into one of the specially designated soft wheat silos.

How high up are we?

We are now 70 feet off the ground.

Oh...I'm really, really trying not to look down. Ooh!

How much wheat is in there?

We have 5,000 tonnes of wheat in this one silo.

How many Yorkshire puddings do you think you could get

out of this silo of wheat?

The wheat in this silo is enough to make

around 416 million Yorkshire puddings.

How long can it stay in these silos?

Up to ten years... Wow! ..as long as it's kept dry and cool.

Inside the silo, the wheat grains are protected by their husks,

and cold air blown from the bottom prevents insects,

fungi, mould and bacteria from multiplying.

So actually, it's thanks to these silos that my family can have

Yorkshire puddings on a Sunday? Yes.

Well, let me just take my hat off to that.

When it's needed, the wheat is taken from the silos,

is milled to make flour, and sent to shops, bakeries and factories,

ready to make all our favourites, Yorkshire puds included.

GREGG: Back at the factory in Hull,

my soft wheat flour has been unloaded,

and Chris and I are heading from the intake bay...

..to the mixing room.

Oh, wow.

Although it's a hall full of high-tech,

the ingredients for the factory's Yorkshire pudding batter

are as simple as when I make it at home.

All we need is the flour that's just been delivered, plus eggs,

milk and salt.

Right, Gregg, this is where we make our batter.

So, we've got the egg coming in from outside,

and then we've got individual flour hoppers

which come from the main silo, which hold enough for one mix.

Can I lend a hand mixing?

Yeah, yeah. We've got a mixing vessel just up here. Show me.

Sometimes on a Sunday, I'll make a dozen Yorkshire puds,

but I'm guessing here, we're supersizing!

How many Yorkies do you get out of each batch?

Approximately 14,200.

And how many of these batches do you make in a day?

101.

Oh, wow!

101 batches times 14,000.

How many Yorkies is that?

About 1.4 million a day.

Wow, that is big production, isn't it?

It's massive, Gregg, it's massive.

Right, I'm happy to lend a hand.

Yeah, yeah, if you're up for it, yeah. Are you quick enough?

I'm eager. Yeah. I'm very eager, Chris.

What do we need first of all?

So, the first part of the mixing process is adding our liquids.

We've got 102 kilos of liquid egg,

a mix of whole egg and egg white,

plus 150 kilos of water.

Right, now what, Chef?

Now we've got to this point, you're good to add your dries.

The first dry ingredient is dried skimmed milk powder,

exactly 5.02 kilos.

Oh. Ah, you're going to have take some out now, Gregg.

That's very precise.

I'm never this precise at home.

But then, I suppose I'm not making a million at a time, am I?

You don't add fresh milk? No.

A dried milk powder has, like, an 18-month shelf life,

whereas fresh milk might have 10, 11 days.

So my Yorkshires at home sound exactly the same as yours.

Yeah. You've got egg, flour, milk and a bit of seasoning.

Exactly. It's just taking that home-made baked process

in your own oven and transferring it

on to a massive industrial scale.

And that means scaling up the next ingredient...

Right, that's on zero.

..from a pinch of salt to 1.2 kilos!

1.2, not 1.02.

Perfect.

So that's egg, milk and salt.

Just flour to add.

There you go.

How much flour gets added to that?

140 kilos.

Where do I get the flour in? If we just start the mixing process.

So, the top button on the left.

Yeah, and then drop your flour,

which is the bottom one.

MACHINE HISSES

With all four ingredients added, inside the mixer, the blade is

attached to a shaft that begins spinning

at 2,950 revolutions a minute.

At home, I would put in the flour first,

and then I would be adding my milk and my eggs afterwards.

You start off with liquid. Yeah, yeah.

And we mainly do that to avoid lumps in our process.

Apparently, you're more likely to get lumps

when you add liquids to dry ingredients,

so here, they do it the opposite way to me.

But let's face it, they are the experts.

We've got our wet and dry ingredients happily mixing.

How long are they going to mix for? Six minutes, Gregg.

We're looking for plenty of aeration.

So, we want trapped bubbles, which will help support

the structure of the Yorkshire pudding when it's cooked.

Unlike bread and cakes, Yorkshires don't use raising agents

like yeast or baking powder, but rely on just air

to give them their lift.

The revolving blade traps air in the batter to create bubbles.

And there's also an important reaction going on.

One of the key components in flour is starch.

So, as we mix, the starch molecules

sort of absorb water and thicken the mix.

That's why Cherry's grain test is vital, so the factory knows

that their flour has enough starch in it to make a lovely thick batter.

We've got a batter mix. Yeah. Where do I go now?

You need to go and see Harry on the production line.

Brilliant. Good stuff. brilliant. Thank you, Chris.

We've got nearly 400 kilos of batter for my batch,

and it's pumped from the mixing room...

..to depositing...

..where I'm meeting Harry Owen.

Hey!

Harry. Nice to meet you.

Gregg. What's your job here, my friend?

So I'm the process technician, so I cook the puddings.

Then I am in the right place.

And this is some place!

It's the heart of the factory,

the Yorkshire pudding production line, 150 metres long

with 310 scorching hot baking trays circling the line.

They're made of nonstick coated steel

and are formed of 60 individual pots,

the exact size of which is a trade secret.

And here at the oil depositor,

each tray gets its all-important coating of oil.

Wow.

How much oil going into each tray?

So, it's around 2g of oil going into each pot.

What oil is that?

So that's a rapeseed oil, that one.

Lower saturated fat and it's a more sustainable product for us.

Rapeseed oil also has a high smoking point,

so it can get really hot before it starts to burn -

important, as the best Yorkies are cooked at a high heat.

It's not unlike a sprinkler on a posh lawn.

A very posh lawn, yeah,

if you were sprinkling it with oil, yeah.

It's vital the oil doesn't cool down,

so as soon as the pots are oiled up...

..they get their batter,

less than two metres up the line

at the batter depositor.

What on earth is that?

That is just a tangled load of rubber tubes.

That's what deposits our batter into the trays.

So, if you just look down there,

you can see them pumping into it.

Yes, I can.

Oh, wow!

The batter comes straight from being thoroughly aerated in the mixer,

so it doesn't lose any of its all-important bubbles

as it passes through the 240 pipes,

which fill two trays at a time.

Why so many pipes? You've only got 60 holes in a tray.

We have two pipes per pot

and that's to get an even distribution of product.

Each pot gets 26g of batter.

So each pipe is 13g.

So we know we're going to get that consistency.

Wonderful. Wonderful, wonderful.

How do you know if one of those tubes has come disconnected?

Which it must do every now and again.

Usually, there's a big pile of batter on the floor.

Of course there is!

GREGG LAUGHS

What happens now? Into the oven?

Well, not until we've checked something really important.

Let me show you.

Right, what am I looking at, please?

So here, we're looking for what we call the halo effect.

So, if you look at each pot,

there's a little ring of oil around each bit of batter.

This halo effect you're talking about,

that is a little film of oil creating, like, a ring, like a halo.

Like a halo, yeah.

As soon as the batter goes into that hot oil,

it pushes the oil to the sides,

starts cooking the outside of the batter, but not the middle.

So, once we get into the oven, that's what gives us

that rise on the side, as the middle is starting to cook.

So, what happens if we don't get that halo effect?

If we don't see enough oil,

then we won't get that rise.

However, if there's too much and all you see is oil,

then it'll cook the middle at the same rate as the outside.

If you don't see a halo effect there,

we'll get something quite flat.

And if the oil covers all of it,

it will come up like a prawn ball.

It will be very stodgy indeed, yeah.

GREGG LAUGHS Brilliant, my friend, brilliant.

You know what cooking is?

It's science meets art.

Over 14,000 Yorkie pots

are forming an unstoppable batter battalion,

and are one step closer to taking pride of place

on top of a mouth-watering Sunday lunch.

But how did roast beef become the English national dish?

Ruth's been finding out.

Ooh, that looks... Can I have that rib of beef, please?

You can.

This is one of the few dishes for which we are internationally famous.

Indeed, many in France to this day still call us Les Rosbifs.

But how did this particular dish

become an indelible symbol of Britishness?

# When mighty roast beef was the Englishman's food

# It ennobled our veins and enriched our blood... #

Back in 1731, a popular ballad even celebrated

our pride in the national dish.

# And oh the roast beef of Old England

# And Old English roast beef. #

To find out more, I'm meeting food historian Ivan Day...

Hello! Hello, Ruth. Come in.

..at his home in the Lake District.

When the French call us Les Rosbifs,

they don't mean it as a good thing.

They mean it is an insult, don't they?

Just as we might call them froggies, you know.

it was jingoism between two nations who at that time were

really at each other's throats all the time.

So, what is the link, then, between roast beef and Britishness?

It starts at an early period of the 18th century

when we're at war with the French.

British farmers were improving their stock,

making their bullocks heavier, producing more lean meat,

and it became cheaper,

so it was more readily available to more people.

The agricultural revolution is... Starts in Britain.

Yeah, and it overtakes the French.

Yeah. There are diary entries of French people astonished at how good

English beef is, and you get the birth of this idea of John Bull,

who is a stocky yeoman farmer class.

The fictional comic character John Bull

first appeared in a satirical pamphlet printed in London in 1712.

He soon became a hugely successful symbol of Englishness,

the embodiment of the superior national character,

made strong on a diet of British beef.

A great contrast to a familiar enemy of the time - the French.

Here's our big and very grumpy-looking John Bull,

and then we've got this skinny Frenchman

with his frogs hanging up behind him.

It just says it all in one image, doesn't it?

So this is a traditional dish.

Roast beef had been around for centuries

and people had thought of it as fairly British before.

But at this point in the 18th century,

it becomes a political hot topic.

And it does become democratised, because it was always a bit

of a luxury meat but as farming improves, beef prices come down.

And in the towns, particularly,

you get butchers who can sell it to fairly ordinary people.

And also, you get certain festival things,

like coronations and jubilees,

they roast whole oxen on the street for the benefit of the poor.

They're getting a share of the national iconic dish.

So beef becomes supreme, it becomes king.

We're lucky to have this amazing rib of beef,

which we're cooking 18th-century-style, on a spit.

We've seen images of roasting spits set up over a fire,

but in reality, meat would have been cooked in front of it.

So in the 18th or 19th century, this isn't the way the poor were eating.

This is people with a certain amount of wealth.

You need a lot of fuel

and you need a certain amount of equipment to be able to do this.

Yeah. I mean, merchant class upwards, basically.

With the joint in front of the fire,

it's easy to keep it beautifully succulent.

So that's the beef, but what about its famous accompaniment?

So, how far back in history does the Yorkshire pudding go?

The first recipe doesn't get published until 1737,

and it's not called a Yorkshire pudding.

In this little book here,

there's a recipe for something called a dripping pudding,

and it outlines exactly the process that we're going to do.

And a slightly later author called Hannah Glasse,

a very famous cookery writer, she gives an identical recipe,

ten years later, and calls it a Yorkshire pudding.

There it is - "a Yorkshire pudding."

It wasn't until a bit later in the 18th, early 19th century

that it got paired with John Bull's beef as another emblem.

Yorkshire puddings got their name as they were a northern speciality.

This recipe is nearly 300 years old,

but the ingredients are the same as today -

flour, eggs and milk.

We've got to whip it up to a nice, smooth texture. No lumps.

I'm just going to very quickly pour it in. Nice, just gently.

Look at that! See the bubbles forming? Oh, yeah!

That's exactly what it should look like.

That looks so delicious!

Oh! Let's get it off and we'll put it over here.

Here we go. Look at that, eh? Oh-ho-ho!

Ooh-ho-ho! Yorkshire pudding and roast beef.

That looks good, doesn't it? That looks perfect, yeah.

So here we are,

part of a tradition that goes back centuries.

You can really see why this became a dish

that we were known for internationally.

So although the actual methods we've used for cooking

is utterly different from modern Britain,

yet this is still recognisably

the dish of the 21st century,

as well as it is a dish of the 18th century.

So, here's to roast beef, past and present.

THEY LAUGH

In Hull, we're now an hour and 21 minutes into production.

The factory's simple, traditional batter is pretty much

the same as Ruth's 300-year-old recipe.

But we're cooking our Yorkies in rapeseed oil, not dripping.

And instead of an open fire,

our puddings are parading into this massive conveyor oven.

It's a gas-fired monster,

wide enough to take five trays side-by-side,

and a staggering 53 metres long.

How long are our Yorkshire puddings in 53 metres of oven?

The oven lasts just under 14 minutes,

but it's split into four zones.

Is it equal times in each zone?

Yeah, so it's a continuous rolling belt.

So, it's in each zone exactly the same,

so it's just under three and a half minutes each zone.

Take me through the zones. Zone one is our pre-bake zone.

So it takes it from the ambient temperature up to 185 degrees.

Gas mark four, gas mark five.

It's in between the two, yeah, around there. Right.

Then we go into zone two, which is where we start bringing in

some real heat. So, we go up to 215 degrees in zone two.

And that is where that halo comes in important.

That's what gives us our rise. So zone two is our rise.

Inside the oven,

the halo of hot oil in the pots begins to cook

the outside of the Yorkshire pudding first.

As the batter heats, the air inside the bubbles expands,

enlarging them.

At the same time, liquid in the batter turns to steam,

expanding them further, causing the edges of the puddings to rise,

giving them their famous shape...

..before they continue their march through the oven.

Zone three is where we bring in our structure.

So what we don't want to happen is it to get through the oven,

and then they just collapse on themselves.

So it hardens the bottom and the sides that bit more,

so it keeps that structure and keeps that well in the middle.

So, what's zone four?

Zone four's all about colour.

It's all about getting that golden brown colour

that kind of we associate with Yorkshires.

It's cooking at home, isn't it?

Just by the tonne.

By the tonne, yeah.

Very impressive, very impressive.

Come on, we've got to see them coming out, haven't we? Can I?

Come on, then.

You explain things very well. Thank you.

Come on, where are they, the beauties?

There they are!

After just 14 minutes,

my Yorkshires emerge bronzed and beautiful.

That's a good sight, isn't it? Look at that.

I wonder how many Sunday roasts are on those trays.

Beautifully toasty.

Look at them.

That's a good sight. That's a lovely sight.

Whoa!

But the heat is considerable, isn't it?

Yeah. So, first things first,

I need you to stick them on for me.

What, they guard your arms?

Yeah, so they're a Kevlar sleeve,

so, yeah, they'll protect you from the heat of the trays.

This is where we do our spec checks

just to check that everything's right with the pudding.

Do you want to take a couple off?

Fresh out of the oven,

the Yorkshires are a blistering 95 Celsius.

Whoa!

Wow!

Every half an hour, ten Yorkies are picked for quality control.

First, the height check.

To make the grade, they've got to be between 60-68mm.

So, we're at 67mm.

Mate, bang-on! And...lovely.

So we are in spec.

But why would they be not the right height?

Well, so, because the egg and the flour are natural ingredients,

they're never the same.

So we need to make sure that, even though the recipe

is still the same and our oven is still the same,

that the ingredients are behaving as expected.

What do you do if they're not the required size?

We have a partnership with a charity that deal with food banks and stuff.

So, nothing really goes to waste.

Any other tests? Yeah, so the next thing that we have to do

is we have to check them visually,

and we're looking for the structure,

that we've got those sides hardened nicely

and we've got that nice fluffy interior.

Well, look, I can clearly see that that is crispy on the outside

and light and fluffy in the middle. There we go. Which is exactly

what we want, right? It's exactly what we're looking for.

Now what? Are you ready to taste one?

That is my particular forte. Right. Okey dokey.

Does it taste like a good Yorkshire?

Well, I don't think it should taste of anything.

What it should be is a texture, that's what I think.

We want a little hint of salt

and a little bit of an egg flavour in there.

You know, you're right.

A little hint of seasoning... Yeah.

..and almost like an essence of egg yolk.

Mate, that is cracking!

I have done a great job here, with your help.

There we go.

So now we need to get them out of the tins.

Do you want to come this way?

1,140 Yorkshire puds

emerge from the oven every minute.

And there's an ingenious solution

to getting them out of their tins.

So this, Gregg, is our de-tinner.

So if you just want to have a peep in there.

Ha!

GREGG LAUGHS

Is it blowing them off?

GREGG LAUGHS

That is genius!

No way, I never expected that.

It's blowing them off!

I just would have expected the tin to flip.

That is extraordinary.

It's like they're all racing to get off the tin!

Ready. Steady. Go!

And they're all charging down the ramp.

The de-tinning machine blasts compressed air at the puddings -

the equivalent pressure of 66 hairdryers.

I think that is proof of just how light Yorkshire puddings are.

Run away! Run away!

Because they're so light,

they don't damage each other as they land.

Where do the trays go now?

So, once they've been through here,

they go back down just to the oil unit that we started at.

And that's why when they get to that point, they're still hot.

And when the trays get back to the oil depositor,

the whole cycle begins again with the next batch of 14,000.

Now, Yorkies might be my favourite part of a roast dinner,

but the washing-up definitely isn't.

Ruth's been discovering

some long-lost cleaning tips from the past.

I'm going to let you in on a secret.

When it comes to pots and pans,

the old Tudor methods are just as effective

and rather more eco-friendly than anything we have today.

I'm at Athelhampton House in Dorset,

where I'm going to share some old-style washing-up techniques

with chef and food writer Roopa Gulati.

Roopa, hello! Hello!

Now, I know a lot about this particular history,

but chefs know all about dirty pans,

and Roopa's brought one from her own kitchen.

I'm going to show you how I normally clean it.

There's something that gives me great pleasure, when I see a pan

that's caked on, and then a bit of a scrub...

..and it's back to new again.

Sounds like I might have a bit of trouble persuading Roopa

that my historical techniques can rival her favourite scourer.

Although the pad goes back to the early 20th century,

the idea of using abrasion is a much older one.

Ah, I see. And I'd like to show you something,

if you'd like to come and have a look.

To demonstrate the secrets of washing-up Tudor-style,

we're heading for the garden.

So this is what I wanted to show you,

this weed, called horsetail.

And interestingly, some of the old traditional names

really give a clue as to how it was used.

It gets called "scourwort"!

As in scour?

This is from Gerard's Herball in 1597.

So, this is a Tudor text. Mm-hm.

And as he says, "the whole plant is also tough, hard,

"and fit to shave and rub wooden things."

So to clean wooden bowls?

And it works brilliantly,

because the plant, within its tissues,

makes little tiny flakes of silica.

It's making a scouring thing within the tissues.

Horsetail, or scourwort,

is a common weed found in gardens across the country.

The silica in its leaves and stems is a hard chemical compound

also found in rocks and sand.

So, what I've got here are a couple of wooden bowls.

Now, they've had porridge in them,

which, as we all know, really sticks. Yes.

It's a challenge and a half. So let's start with a bowl.

Just a little bit of water.

But it is coming off!

Just lifts it straight off.

That's incredible.

Those little tiny bits of silica are really tiny

and that means they get into every nook and cranny in the wood. Yeah.

Silica, derived from quartz, is still used

in some modern scouring powders.

I am so impressed.

Give it a rinse. Get rid of the leaves.

Get rid of the leaves and I'm done! And then you're done.

It is nature's scouring pad.

Wooden plates weren't the only tableware to clean

in the Tudor kitchen.

After a feast, with platters of meat piled high,

someone had to tackle the pots and pans.

So, a big pan full of grease.

So for that, we need the magic ingredient,

which is this stuff here. What's that?

Well, this is wood ash.

It's straight out of the fire.

So you're saying you can clean all that grease... Yeah.

..with a little bit of wood ash from the grate?

Wood ash from the grate.

Now, within it is this chemical, potassium hydroxide.

It's going to cut grease,

and it's going to kill bacteria.

So I can pop a bit of wood ash in.

Then I need a bit of hot water...

..just to sort of activate it.

And you can see already, the heat starts to melt the ash. Yes.

Potassium hydroxide can be corrosive,

but this small amount of wood ash and water

forms a very mild solution.

You can see the way it's cutting through the grease.

That is the chemical starting to do its thing.

And the horsetail comes into its own again. Look at that. Yeah.

Potassium hydroxide is an alkali, and when it's mixed with

the fatty acids of the grease, it creates a simple form of soap.

It also acts as a disinfectant

by destroying the cell walls of fungi and bacteria,

and is still used in some modern cleaning products.

Who would have ever thought?

That's heaps better than it was.

Age-old technology.

This method of using ash was global.

The only reason it changes is that we run out of wood ash.

And why did we run out?

It's all about cooking fires, about changing over from wood to coal.

In 1570... Yeah. ..Queen Elizabeth is on the throne,

Queen Elizabeth I, the last of the Tudors.

We're still a wood-fired nation.

Within 30 years...

..London has become a coal city.

As the population of the city grew,

the high demand for firewood made it more expensive,

so Londoners turned to cheaper coal to burn in their fireplaces...

..meaning no more wood ash.

And then what happens? Well, then, you have to use soap.

Before that, nobody bothered with soap. No, you didn't need it.

Even today, the old washing-up method could still come in handy.

If I was to go camping, and you've forgotten your washing-up liquid,

and all the rest... Perfect! And it can be as hygienic as anything,

because the wood ash is not only cutting the grease,

it is destroying bacteria.

Works a treat. It looks clean.

It is clean. And it's even sterile.

And eco-friendly, too. And eco-friendly, too.

Back at the Yorkshire pudding factory in Hull,

we're two hours and 15 minutes into production.

My batch of Yorkies are hot out of the oven.

But we're making frozen puds,

so in just three minutes,

they travel by conveyor from de-tinning

to the freezer...

..where Harry's waiting with some cosy-looking kit.

Now, then, Gregg, I need you to pop that on for me.

That looks ominous. It does.

There we go, Gregg. Oh! Whoa-ho-ho!

Well, the contrast between out there and in here

couldn't be more different, could it?

What is it in here, minus what? About -30, yeah.

We're always told not to put hot food in a freezer.

We are, yeah. There's a bit of a difference between our freezer

and kind of a domestic freezer.

This one is a lot bigger and a lot colder.

What's a domestic freezer, about -20?

It'd be around about -18, -20, something like that, yeah.

Why are they going round and round?

So this is a spiral freezer. We use it for a couple of reasons.

It saves space on the factory floor, for a start.

And we can get an airflow that we need

to really blast freeze those puddings.

What temperature do you need to get them down to?

So we need to get them down to -18 degrees.

And how long does it take to get them down to that?

So the freezer in total is 16 minutes.

So they go from about 95-98 degrees

when they exit the oven, to -18 at the end of the freezer.

So why do you freeze them so quickly?

If you think of freezing as kind of freezing it in time,

and it means that the puddings just don't deteriorate at all, really.

Freezing the Yorkies doesn't just make it convenient for us at home.

It also means they can be made to the traditional recipe

without any preservatives.

By freezing them, the factory extends the shelf life

by up to a year.

What you've got is a merry-go-round for Yorkies,

that's what you've got there, mate.

We have a 14-tier merry-go-round.

The 14 tiers can hold over 18,000 Yorkshire puddings at a time,

all working their way up the spiral freezer.

Look, I was really hot, and it might surprise you to know

that I'm really, really cold. Can we get out of here?

Yeah, we'll get out.

Oh, my glasses have steamed up!

My Yorkshires exit the top of the freezer

and are carried away by a vibrating belt that removes excess oil

and stops them sticking to each other.

And now they're frozen, we need to pick up the pace...

..so the Yorkies travel along 25 metres of conveyor

to the packing area,

where I'm meeting packing technician Zara Williamson.

This is where the magic happens with the Yorkshire puddings.

GREGG LAUGHS

Is that right?

What's this machine doing?

So this is dropping ten Yorkshire puddings into a bag at the bottom.

Always ten? Yes.

And is there a specific weight that needs to be in the bag?

We're aiming for 190g.

Ten Yorkshire puddings in a bag always weighs 190g?

Yes. So what do you call these metal cups?

Hopper heads. And how many hopper heads on each machine, then?

There's 16 hopper heads on each machine.

The perfect Yorkie weighs 19g,

but although they're made from the same amount of batter,

they can differ in weight by a gram or two.

So, the multi-head weighing machine uses delicate weigh cells

inside the hoppers to find ten puddings

that add up to exactly 190g.

So if one's 20, it's looking for another one that's 18?

Absolutely. Brilliant! Brilliant, brilliant!

If one's 19, it's looking for another one that's exactly 19?

Yeah, that's right. And is that doing this all the time? Yes.

So to me, it just looks like they're falling through the holes.

ZARA LAUGHS

But it's weighing them all up.

it's actually a crucial part of the job.

How fast is it doing it?

Super fast. It's 8,100 bags an hour.

That's mind-boggling.

Over a tonne an hour.

Why did you need to do it so quickly?

So the Yorkshires don't thaw.

So, over a tonne of frozen Yorkshire puddings every hour,

perfectly weighed, perfectly bagged in tens? Yes.

Can I see what happens to them down there?

Yeah, 'course you can.

Hidden inside the bagging machine,

135 plastic bags are filled with ten Yorkies every minute!

So this is the sealing machine.

So this is sealing the top and the bottom of the pack.

There's two clamps on the jaws, which are hot, which are sealing

the bottom and the top end.

Grab a bag and I'll show you.

That's funny because the bag's, like, frozen,

but the top and the bottom are almost hot. Yeah.

And we also have an air pocket at the top of the seal,

which allows air to escape.

Ah! So when we're packing them into the boxes,

we can pack them nice and neatly...

Brilliant! ..and they don't get damaged.

The air pocket lets air out when pressure's applied to the bags,

so they don't burst if squashed.

And it doesn't let air back in again,

because the pressure is the same outside and inside the bag.

Are these ready to go in a box now?

Just one more test. Follow me.

What are we going to do?

We're going to cook them. Well, you're going to cook them.

Why are we testing them? We've already tested them once.

Because we need to make sure that they taste as good as they did

when they came out of the oven.

Obviously, they've been frozen,

so we need to make sure they taste the same.

Because the Yorkshires have already been cooked,

they just need five minutes to heat through from frozen.

Excellent.

EGG-cellent!

ZARA LAUGHS

Well, if anything, they've got an even better colour.

Nice and crispy.

Not at all greasy.

I'll give you this.

I can't tell the difference between when they were cooked

before they were frozen and cooked after they're frozen.

And that's what we want.

So, well done, you. And you. Well done, you.

Well, yeah, they were going to be perfect, weren't they? They were my batch!

I had all confidence.

Of course, a perfect Yorkshire pudding is nothing

without the perfect sauce.

So, Cherry's finding out how to become a gravy guru.

CHERRY: There's nothing worse than slaving for hours over a roast dinner

only to have an epic gravy fail.

It's lumpy, it's thin,

it's salty, it's oily,

and it's a bit of a mood dampener on a Sunday.

To prevent another gravy catastrophe,

I've invited food scientist Barbara Bray to lunch.

Barbara... Hi! ..perfect timing! I need your help, come in.

I'm hoping her knowledge of molecular gastronomy

will transform my Sunday roast.

One thing I do know is that my meat needs to rest.

And while it's doing that, it's the perfect time to prep our sauce.

First up, the stock,

and I'm really hoping there's a short cut.

You can do it the traditional way,

where you're boiling bones of beef and vegetables

for four hours and reducing it right down, or...

BOTH: Or...

..we can use the help of science...

Hooray! ..and have ready-made stock.

It has taken all the components of what we would have had

in a traditional stock, but it's a dried powder

or it's a stock pot.

The short-cut stock cube is made by dehydrating ingredients

such as meat, vegetables and herbs,

with the resulting powder formed into a cube or jelly pot.

But we're after an extra hit of flavour,

so we're adding roasted carrots, onions, garlic and celery.

We've used a high heat

and that's caused something called caramelisation.

So, you can see there that the vegetable's gone really brown.

That's actually the result of something called pyrolysis.

What is pyrolysis?

Pyrolysis is when you're using really high heat

to induce caramelisation.

What happens is the sugars are stimulated into this chemical

reaction, and the browning reaction starts to happen.

In our gravy, we want those rich flavours, the nuttiness

and the toastiness that we get from that caramelisation.

We're putting them straight in

and the flavour will infuse out into the liquid.

That helps us impart intense flavours into our gravy

in a fraction of the time that we would have done

with a traditional stock.

While the meat's been resting,

its connective tissues have relaxed,

and most of the fat and moisture has been reabsorbed by the muscle fibres

of the meat, which means this joint should be tender and succulent.

The remaining fat and moisture in the pan

provides another layer of flavour for our gravy.

What we're going to do is just separate the liquid from the fat,

because we don't want our gravy to be too fatty.

Are there any, like, tricks of how to get rid of it?

Pop a couple of ice cubes into the dish,

and the ice will reduce the temperature.

And animal fat, when it gets cool, it solidifies,

and it makes it easier to catch the fat.

Oh, look at that!

You're coating the ice cube with fat.

Yes. Oh, listen, this is the best trick ever.

I'm going to use this so many times.

Next job is to deglaze the pan.

We're going to take a cup of hot stock,

add it to the pan to loosen the residue

that contains that beautiful rich flavour.

The good bits. The good bits!

Just like when we roasted the veg,

the flavour-packed good bits result from caramelisation,

as simple sugars in the meat juices brown in the pan.

It's still a bit soupy, Barbara.

We need to thicken it. How do we do that?

So, what we do is we take wheat flour,

and we add some of the fat that we scooped out of the pan,

and we put it on a high heat.

And the purpose of doing that is to get rid of that raw gluten flavour.

This mix of flour and fat is called a roux.

And heating it to remove the raw flour flavour

is known as cooking it out.

It'll start to smell a bit more like a cooked flavour.

And then you'll see the colours change,

so it'll become darker and darker - what's called the Maillard reaction.

And that is the interaction between the amino acids from the protein

and the sugar molecules.

And that's what releases those fantastic flavours.

And in order to get the good consistency, you're now going

to keep topping it up with hot water.

The Maillard reaction deepens the colour of the roux

and gives it a toasty smell and flavour.

It's also responsible for the flavour,

colour and smell of meat roasted in the oven.

When combined with the caramelisation of the roasted veg,

both these chemical reactions will give our gravy layers of flavour.

We're now going to thicken the stock.

Pop the roux into the stock pot and we'll set up a process

that's called gelatinisation, which is where the starch in the flour,

which has lots of little molecules of glucose in a chain together,

starts to swell and absorb that moisture in an irreversible manner.

And that's what's creating this jelly-like substance.

So, it's getting really lovely and thick,

just that kind of gravy texture that you want.

It is time. Are you ready?

Thanks to science, we might just have the perfect gravy!

But to give it the definitive seal of approval,

I've invited a most discerning critic.

Barbara, can I introduce you to my mother, the gravy connoisseur?

Hello, nice to meet you.

So, we have worked pretty hard to create the ultimate gravy,

but really, we'll never know

until you tell us whether we have achieved it.

I do like that. So, this is delicious.

It's just got so much flavour.

It's velvety smooth.

It just is such a fantastic complement to the meat

and the vegetables.

Thank you for all your amazing tips.

Cheers, everyone! To the glue that holds roast dinners together...

Cheers! ..the gravy. Hooray! Cheers!

At the factory in Hull,

we're over two hours and 44 minutes into production...

..and these Yorkshire puds are nearly ready for some of that gravy.

My batch of 14,000 Yorkies are made

from the same simple, traditional recipe as home-made.

There's just a lot more of them!

I'm with packing technician Zara,

following the puds through the factory

to the boxing station.

And there are no high-tech robots here.

They're packed by hand, the old-fashioned way.

So shall I grab a box or what? Yep. Let's do it.

So how many have I got to put in?

So we want ten in a box.

One, two...

You've got to act fast, Gregg. We don't want them to thaw out.

..five, six...

Oi!

This is where the air pocket comes into play.

I see, as you squeeze them down, so the air comes out,

so you can get them in nice and flat. Yeah.

Without that, you wouldn't get ten in a box.

You wouldn't get ten in, no.

You can clearly feel the air

coming out of the bags.

The Yorkies could defrost in just 20 minutes,

so it's a speedy process.

But thanks to the perfect amount of air in the bag,

we're in no danger of damaging them.

So how fast are we doing this?

We're packing 12 boxes every minute...

Give me a box, give me a box! ..which is 720 boxes an hour.

I'm good at this.

This is a job cut out for me, this is.

Look at that, look. Look at that. Excellent.

Brilliant. Absolutely outstanding job, Wallace.

Give me a box! Give me a box! Come on!

You're holding the line up!

ZARA LAUGHS

It's absolutely brilliant.

Wow, look at that.

I reckon you're burning calories with this. This is a workout.

Agh! They're piling up!

They're piling... That's why we've got to be quick!

They're piling up! Quick!

We'd better go. Look, it's piling up. Quick, just get out.

Just blame me.

Left to the experts, it takes just 12 minutes to box up

my batch of over 14,000 Yorkies.

Still frozen, they're sent straight from the boxing station

to the final leg of their journey - dispatch.

Yes! So is that my batch?

That is your batch, yeah.

How many pallets do you get on a truck?

56.

And do you know how many boxes that is?

So there's 45 boxes on a pallet,

which is 216,000 Yorkshire puddings.

Ooh, good numbers! Good numbers!

And so how many times does a truck leave your factory?

So we have roughly about 16 lorries every single day.

So how many individual Yorkies is that?

About 1.4 million.

That means in the UK, we're eating more than a million Yorkies a day?

Yeah. Even if you account for people like me,

that have five or six at a time? Yeah!

It's just two hours and 56 minutes since the production clock began...

..and the temperature-controlled lorry is filled,

and my batch of 14,200 frozen Yorkies

are heading out of the factory.

The Yorkshire puddings are sent to retailers all across the UK

and the Republic of Ireland.

We munch on them all year round,

but eat more in December than in any other month.

Like a lot of people, I buy ready-made Yorkshire puddings,

but what's impressed me here is, despite the massive scale,

it's not unlike making your own at home.

The mixer may be a monster,

and the oven a lot bigger...

Whoa!

..and hotter,

but the ingredients and process for making these British classics

are as simple and traditional as at home.

it's just this factory's production is supersized!

I had no idea just how much we loved our Yorkshire puddings.

They make 500 million of them every single year.

That is staggering!

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.