How hot do you think curry cook in sauce has to be to last for two years?
Pretty spicy, I would say. Definitely spicy.
Do you reckon all ice cream is the same temperature?
Oh, no. If it's really, really cold, it's icy.
Ooh, there's nothing like losing your Flake!
Why is hot and cold so crucial to supermarkets and the way that they make our food?
Have you eaten these before?
Maybe. Do you think you'd have to heat them up or cool them down?
You don't dissolve it, no?
Ooh!
I'm going reveal the secrets behind some of your favourite foods by making them, Food Factory-style.
Every kitchen has a cooker and a fridge-freezer.
We'd be lost without them. But why do supermarkets rely on extreme temperatures to make our food ?
To find out, I'm going to go back to basics and set up my own factory production line in this barn.
It may look as though it's full of junk, but it's got everything I need
to discover the secrets of supermarket food.
But first, I'm off to the seaside.
Nothing better on a typical British summer's day than a cold ice cream.
Mmm!
Lovely. But there's so many to choose from
and in recent years, there's been an explosion in the ice cream aisles.
But a lot of us are happy with just one type of ice cream -
soft serve.
Right, guys, got some ice creams here, we've got a soft ice cream.
One that's a little bit harder. I want you to taste them and tell me which one is sweeter.
Yum!
This one. You think that one is?
That one. Why do you think it tastes sweeter? Is there honey in it?
Cos it's more processed? It's probably got more sugar in it.
If only it was that simple.
You better hurry up, it's melting!
It's the ice cream van classic.
Unlike the ice cream you scoop out of a tub, this stuff is made on the spot inside a machine,
usually out of a liquid ready mix or powder that the ice cream man adds water to.
But what's happening inside the machine to make it so soft?
And why does it seem sweeter than normal ice cream?
To find out, I'm going to make my own.
Here in the barn, I've got everything I need
to defrost the secrets of soft serve ice cream.
First, I want to have a look at the basic ingredients of ice cream.
You don't have to be a genius to work out it includes ice and cream.
Got some lovely cream in here.
In it goes,
some sugar to make it nice and sweet,
and I'm going to put in a few drops of vanilla essence.
That'll do it.
Right. Now it's time for the ice.
The ice comes from the water that's already in the cream.
I've just got to freeze it.
I could stick it in my freezer and stir it every so often,
but there's a much quicker way - liquid nitrogen.
This mega cold stuff is minus 196 degrees centigrade.
And all I've got to do to freeze my cream into ice cream is pour it in.
Right, here we go.
Ah, look at that.
So the liquid nitrogen is freezing the cream.
I've got to keep stirring it - it's important to get air in.
Without the air, I'd end up with rock hard frozen cream.
Look at it all billowing out of here.
It's like I'm making some sort of potion, I feel like Harry Potter!
Look at this!
That looks like ice cream to me. Let's have a little taste.
Nice and creamy, not too bad.
Bit space age for me.
So that's the quick way to make ice cream.
But you won't get many ice cream men making their 99s that way.
What they want is a cheap and easy way to make ice cream in the back of their vans.
They buy something called premix.
The ingredients of premix are a tad cheaper than you get in posh luxury ice cream.
Instead of cream, the premix uses long life skimmed milk.
Next, it's skimmed milk powder.
Give it a whisk as I put in.
Mix it all up nicely.
Next up, vegetable fat.
That often means palm oil.
It's in loads of things and it's proving controversial.
Palm oil plantations replace lots of rain forest.
Right, time for a bit of flavouring. Nice bit of vanilla.
Now, sugar. Now surprisingly, there's less sugar in this recipe
than there is in traditional ice cream. So how does that work?
In fact, your posh luxury ice creams can have DOUBLE the amount of sugar
that soft serve has.
It looks disgusting, but it smells lovely.
Slowly heat this mixture up.
It seems bonkers heating up ice cream.
But it's important to kill off any bugs in the premix
before it goes on the road in the ice cream van.
So with my premix prepared, I need an ice cream machine.
First, a box to put the ice in.
Then something for the cream.
I'm lashing together a drain pipe and a drill.
This may look like a mad contraption,
but it's based on what you find in the back of ice cream vans.
It's going to act as a freezing barrel.
I'll put the cream inside the tube and cover it with ice.
The spiral turns, mixing up the ice cream,
as it goes along here,
it should be forced out through my tap at the end.
That's the theory.
Later, I find out if my makeshift freezer really is as cold as ice.
At the opposite end of the temperature spectrum is curry.
It's one of Britain's favourite foods and we like it hot.
In fact, we get through nearly three quarters of a million jars of cook-in curry sauce every week.
But how do the supermarkets guarantee this spicy favourite
is still good to eat years after it's made?
How long do you reckon that will last in your cupboard?
About two weeks. Two weeks, yeah.
Three months. Three months? About a year.
Two years is the actual shelf life.
What do you think they do to it to make it last so long?
Seal it up. Seal it up?
Preservatives, artificial preservatives? Possibly.
Heat it. Heat it? But we eat a lot of curry.
I eat a lot of curry so it doesn't last that long, does it?
When you see food in a jar, you might think the jar's the secret
to keeping it fresh, but there's a lot more to it than that.
At this factory in Birmingham, they know what makes a good curry,
but how do they give it a long shelf life?
# I fell into a burning ring of fire... #
It's Gary Hoyle's job to make sure this curry sauce will still be safe to eat in two years' time.
Right, Gary, I love curry.
This smells amazing, what have we got cooking in here?
We've got a batch of Jalfrezi sauce.
Can I open her up? By all means, open that up.
I've got to say, I've been so excited about this. Look at that.
There you go. Right, look.
That is lovely!
I could do with a naan. A naan and a cold beer!
Cold beer, that's right!
In this factory, they cook curry like you would at home, but on an industrial scale.
Check that out for a tin of tomatoes!
All this curry you make here, now if I was to make this at home,
I'd have to eat it pretty quick, it'd go off quick, wouldn't it? It'd go off in a couple of days.
How do you make it last, do you put preservatives in it? Absolutely not.
We just cook it to a pasteurisation temperature, which helps kill most of the bugs.
They heat the sauce to 90 degrees centigrade for 10 minutes.
But that doesn't kill all the bacteria that could make you ill.
Why don't you just keep heating it hotter and hotter and hotter?
That would destroy the product.
You'd end up with a soup-like curry with no texture in there whatsoever.
That doesn't sound like my kind of curry.
As heat won't kill all the bugs, Andy needs another line of defence,
and it's something that's already in the curry sauce.
There's a lot of tomato in this Jalfrezi curry sauce
and that's what we've got here. Tomato is quite tart,
but that's because it contains acid?
Yes, and the acid helps preserve the product. How does that work?
The acidity means the bacteria can't grow.
How can you tell when you've got enough acid in the sauce? We analyse a sample.
Arnold's our process supervisor here. How you doing? Nice to meet you.
He'll analyse the sauce. OK?
I see Arnold's using the chemistry set you got for your birthday? That's right!
Too much acid and the sauce would taste horrible.
Too little and it wouldn't be safe to eat.
Look at that, that's it. Change.
Tell me, fellas, what happens if the sauce isn't right, if it hasn't got enough acid in it?
We have to make minor tweaks to the recipe, so we use some
of the natural ingredients that are already present in the sauce to increase the acidity slightly.
Based on the recipe that we have at the moment, there's lemon juice.
This stuff here? Yes, that stuff there.
That's concentrated lemon juice, is it?
Exactly. Let's have a little taste.
I think putting that in a curry would make it taste disgusting.
Just be careful with it, but you wouldn't taste it. Urgh!
THEY LAUGH
The key thing is we balance that out with other ingredients!
Believe me, you would not taste it. That is the worst thing!
Oh, that is so...concentrated!
Makes your lips smack, doesn't it?
You wouldn't want that in a curry sauce.
You wouldn't notice it, though.
You don't notice it, it's in there at low level, but it's only a very small tweak
in the amount of lemon juice that he adds to a 1,500-kilo batch.
So Arnold's like a wizard, he's like the potion master, getting it all just right.
Brilliant!
So the sauce is set to last for two years, but heat is still crucial as it's packaged.
The battle against the bacteria continues.
You can see all the steam coming off the jars.
Why are you putting the curry sauce in so hot?
Because hot curry sauce will kill any potential bugs that are in the jar.
Now when it comes to keeping curry sauce, it's not spicy heat that counts, it's the temperature.
Which means this stuff can last in your cupboard for up to two years.
But if you're a curry fan like me, well, it's not going to last that long. Can I have this one?
Yes. Thank you!
Back at the barn, I'm defrosting the secrets of soft serve ice cream.
I've built my own freezer,
a bit like the one you'd find in the back of an ice cream van.
And I've made my own creamy mixture, now all I've got to do is freeze it.
Getting the premix into the chamber's the easy bit.
Turning it into ice cream is going to be the hard bit.
In a normal ice cream van, they would chill all this down with an electric freezer.
But I'm going to use this, dry ice.
Carbon dioxide that's so cold...
it's turned into a solid.
Look at that, it's like Top of the Pops. Here we go. Pour it all in.
Right, that's all the dry ice packed in.
Now all I've got to do is to start turning that premix
so it doesn't freeze where it is right now.
Here we go.
I need to get air into the mix
to make sure my ice cream ends up light and soft.
# Freeze! #
So, I'm using a power drill to keep the spiral turning.
Now as the blade is going round and round, it's mixing all the premix up
and it's putting lots of air in there
and that's exactly what I want to make it nice and light.
Plenty of air bubbles.
Lots of air is the secret to making soft serve ice cream soft.
Believe it or not, around half of my ice cream will be fresh air.
Now I've started this, I haven't got any idea how long it'll to take.
I thought it'd be quick, I didn't think it would be all night long.
Although the dry ice is super cold, I only want my ice cream to go down to about minus five.
And that's the big difference with soft ice cream.
It's not as cold as ice cream you might have in your freezer, that's about minus 18.
There are two advantages to that.
Firstly, it's less of a shock in your mouth and secondly, it also tastes sweeter.
Bizarre as it may sound, when you eat something really chilly,
it stuns your taste buds.
That makes it harder for them to detect sweetness.
I'm not sure about the ice cream, but I'm getting freezing!
So even though soft serve ice cream has less sugar than traditional ice cream, it tastes sweeter,
because it's warmer.
Amazing!
Right...
Let's see what it's like.
Oh, no! Look. I've got it...
Ha, ha, ha!
I've got it coming out of both ends!
Oh, no! HE LAUGHS
Hoo-hoo-hoo! Let's try and fill this.
Look at that!
Well...
..the flavour's there, but I think mine's a bit of a flop.
We're not singing "Freeze A Jolly Good Fellow" yet,
my ice cream isn't cold enough, and my machine is on the blink.
I've got a bit of a problem here.
This end, really, really cold, this end, really hot.
I think my drill is beginning to burn out.
There's actually smoke coming off it. I'm so close.
My drill may have packed in, but I'm not giving up.
Time for a bit of elbow grease.
If I don't keep the cream turning, it will freeze solid.
That's lot of effort for one cone... of soft serve ice cream.
You'll need an ice cream after this, you're so hot and worn out!
# Work till you're muscle bound, all night long. #
I've waited long enough for this, I'm going to make sure I get a big one.
Right, there we go, that's it.
Look at that.
If I got that at the fair,
I'd be really pleased. That's my own...
soft serve...
ice cream.
Oh, and it tastes like the real deal as well. The texture's right.
You know, it's got all these lovely little peaks and it's not sagging.
That's brilliant.
But what a lot of effort for one ice cream!
There we go. My very own...
soft serve...ice cream.
Brilliant!
Later, I tried out my ice cream machine down on the farm. Bit runny.
Oh, lovely(!)
And once again, I was having some hot and cold problems.
Is it as good as the ice cream you get off the ice cream man on the beach? No.
Why not? Because it's all sloppy.
It's all sloppy!
What a mess you've made, haven't you? But what did it taste like?
Yummy. There's one problem with my ice cream, it melts too quickly.
But once I got my machine working properly... Thank you.
..everyone wanted seconds. How did the ice creams taste?
Lovely, really nice. Nice and sweet?
Yeah, really good. Just like one in a shop.
It's really good. The texture's nice as well.
You scoffed yours really quickly! You've got to when it's that good!
When it comes to extreme temperatures, ice cream and curry sauce are fairly obvious.
But there are some vegetables that need the big chill and a race against the clock,
to make sure they arrive in the supermarket in tip top condition.
After 80 days basking in the Scottish sunshine,
the leisurely pace of life is about to change dramatically.
It's harvest time for Alastair Ewan and his broccoli.
# Life in the fast lane. #
The race is on when it comes to harvest,
to make sure it keeps its freshness.
Right. Because broccoli's got a secret.
Oh, yeah, what's that, then?
You're actually eating the flower buds.
Seems hard to believe, but broccoli is a bunch of flowers.
This is like a field of roses. Fancy a few flower buds for tea?
Look at these. Look at that! Yeah.
So that is a broccoli plant, isn't it?
Yep, there we go. It's going to be a bunch of flowers eventually.
In fact, it is quite pretty, I could probably get away with givin this to my wife for Valentine's Day.
I think you've got no chance!
You'd never think the part of broccoli we eat is a mass of tiny flower buds.
And like a bunch of flowers, broccoli wilts really quickly.
This gives farmers a real headache.
Here's one that has been discarded and look at the difference
between that and that. That's been cut and left in the sun? Yeah.
There's a big difference. This one, if I shake, nothing happens.
This one, it's all over the place, like jelly.
Broccoli goes floppy within hours of being picked and that's no use to shoppers.
Rob Stockwell has got to make sure this crop lasts much longer.
Hello, Rob. Hi, Jimmy. How are you? Not too bad, thank you.
So what would the shelf life be on a bit of broccoli like this? It'd be about four days.
Two days in the supermarket, on the shelf and another two in your fridge at home.
What's the secret of keeping it nice and fresh like this?
The secret of this is all about timing.
As soon as we've cut it, it has to get into the chill as quick as possible.
It's a race against the clock.
Only by getting the broccoli icy cold fast can Rob give it four days' shelf life.
What does the chilling do to the broccoli? Basically, it slows the whole process down.
It means that the head keeps its moisture, keeps it fresh, keeps it crunchy.
So it extends the shelf life, because once you've cut it, basically, this is slowly dying.
So in a way, are you extending the suffering of broccoli?
No, I'm giving you extended pleasure!
# Daddy cool, daddy cool
# Cool daddy, cool
# Daddy cool, daddy cool... #
Well, Alastair, it's freezing in here, isn't it?
The temperature's set at about one degree.
Here's some broccoli that's been in here for two hours, it's not fully chilled,
I've got a thermometer here, you try it and see what it says.
Like you get at the doctor's. Usually it goes in your ear or your mouth. Not up your broccoli stem!
Now how quickly has it got to get to temperature?
I like it down below five degrees within a couple of hours and get it
right down within five or six hours to one to two degrees.
Look at that, that's dropping really quickly.
Well, that is 5.5 degrees Celsius,
which is amazing, but I am freezing, so I reckon, we need to get out.
Yes.
# Daddy cool, daddy cool... #
To make sure the broccoli is kept in tip top condition,
it's a race to the fridge and minutes saved on the farm
could give you days longer to tuck into your greens.
What do you reckon these are?
It is a food, is it? Yes. A very thin crisp.
A very thin crisp? Looks like a bit of plastic to me.
They do. Do you think you've eaten one of these?
I'd never eat one knowingly. No.
I reckon you've had them before. I haven't. I've honestly never seen one before.
Do you ever go to Chinese restaurants? These are prawn crackers,
but to go from this into this, takes a lot of heat!
And I'm not just talking about the heat in your deep fryer.
There's more to it than that.
To explode the secrets of this featherlight snack,
I'll need to draft in some heavyweight kit.
Now the best place to start with any food puzzle is on the ingredients label.
And the surprising thing is, prawn crackers actually contain prawns.
About 7% in these.
But what it doesn't tell you is how you turn them into the bizarreness that is a prawn cracker.
I'm starting with the traditional method.
All the ingredients are natural.
They've been making prawn crackers by hand in Asia for generations, so you'd think it would be quite easy.
First job I've got to do is puree my prawns.
Next I need to make a dough from tapioca flour and some water.
It's almost like wet chalk.
Right, that's my dry tapioca dough made...
..and I need to add it to my prawns.
Seems like a waste of good prawns, really.
The reason I'm using tapioca flour in my dough is because it has more starch than most other flours.
And starch is the magic ingredient in prawn crackers.
It's what makes them crunchy when you fry them.
It's really odd having a fishy dough.
But I'm a long way from turning these prawny sausages into crunchy crackers.
For the starch to do its job, it needs to be softened up, so I'm doing some steam cooking.
Let's pop these off.
Little bit sticky.
It's like a jelly baby's poo!
Looks so weird! It looks nothing like a prawn cracker.
However, if you leave it in the fridge for a couple of days...
..it looks nothing like a prawn cracker!
It's a less sticky alien sausage.
So after two days in the fridge,
the sausages have firmed up enough to slice.
But to have any chance of puffing up these discs into crackers,
they need to be much drier.
So it's into a low lazy oven for about four hours.
Prawn crackers certainly aren't a fast track snack.
Look at that...
they are really dry.
Right, first cracker, ready to go in.
The hot oil turns the tiny amounts of water left in the discs to steam.
Hee! Look at that.
And the steam forms tiny bubbles, which make the disc expand.
That is brilliant!
Mine are a little bit smaller, but look, unfolded brilliantly.
See all the tiny bubbles there? Fantastic, let's have a taste.
Mmm. Lovely crunch.
But they've taken me ages to make.
So it's no surprise food factories have hit on a way to make these much, much quicker.
Their trick is to make the crackers using less water, but with a massive amount of pressure and heat.
This should speed up the whole process.
This is heavy stuff. Might be a bit of overkill to make some small prawn crackers.
Instead of using this 20-ton hydraulic jack to change a tyre
on my tractor, I'm going to use it as a high pressure crusher.
It might look crackers, but I'm hoping it will
work some magic on the starch in my prawn crackers.
The ingredients this time are tapioca flour again,
prawn extract and just the tiniest splash of water.
Right, pop it all into my coffee grinder.
Give a quick whizz.
It's so dry that instead of a dough,
I'm left with this powder, full of starch.
But instead of steam cooking the starch, I'm going to use high pressure and heat.
This should melt and squash it together to make a prawn cracker.
Right, I'm going to put my mix into this little receptacle
and put a lot of pressure on it with this 20-ton hydraulic jack.
In the factory, they obviously don't use a hydraulic jack like this
This is something you'd lift a truck up with. They have a machine called an "extruder"
that applies a continuous pressure that grinds up all the starch.
I'm hoping this will do a similar sort of thing.
That's a lot of pressure. Now for a bit of heat.
I'm hoping this pressure and heat will melt the particles of starch
and leave me with a prawn cracker that's made in minutes instead of days.
I think we're there.
Let's see what we've got.
Don't have to do this in the takeaway, do you?
Look at that! It is absolutely amazing, really.
It doesn't look brilliant, needs a bit of tidying up, but you know what?
I'm really proud of that.
After all the pressure and all the heat, it's fused...
..almost like clear plastic. Incredible.
Of course the proof of a prawn cracker isn't in what it looks like.
It's what it does when you fry it.
Will it puff up?
This better work.
Right, in you go, hot oil.
Little bit nervous.
Come on. It's going to do it.
Woo hoo! God, that's really quick.
Tell you what, my prawn crackers don't hang about. Look at that!
That's what you call a lightning prawn cracker.
Unbelievable, boosh! Straight away.
Now that's a lot of work for one cracker.
Now if I ran a Chinese takeaway, I wouldn't give these away for free.
Now let's have a taste.
SHARP CRUNCHES
Did you hear that crunch? Oh!
That's brilliant, lovely crunch.
It's just a prawn cracker all over. What a success!
There we go, my very own prawn crackers.
From hot, hot curries...
That is the worst thing!
..to cold as ice cream...
I've got it coming out of both ends!
..I've turned up the heat on the temperature tricks of mass produced food.
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