0:00:04 > 0:00:08How often do you stop and really think about your food?
0:00:08 > 0:00:11Look at all this lovely fat and sugar. Yummy.
0:00:13 > 0:00:17Do you ever wonder why you eat what you eat,
0:00:17 > 0:00:20what cooking does to food...
0:00:20 > 0:00:21Delicious.
0:00:21 > 0:00:24..or what effect it has on your body?
0:00:24 > 0:00:26I trained as a medical doctor
0:00:26 > 0:00:28and I'm absolutely obsessed by nutrition
0:00:28 > 0:00:30and the hidden chemistry of food.
0:00:30 > 0:00:34So, I've teamed up with botanist James Wong to explore food,
0:00:34 > 0:00:37each of us coming from very different perspectives.
0:00:37 > 0:00:39Truly delicious.
0:00:39 > 0:00:41Together, we have taken over
0:00:41 > 0:00:43the country's leading food science lab...
0:00:45 > 0:00:48..to deconstruct some of our favourite foods...
0:00:48 > 0:00:50It's all sunk to the bottom.
0:00:50 > 0:00:53..and to reveal some truly remarkable secrets.
0:00:53 > 0:00:58I want to find out what effect food has on us and our biology,
0:00:58 > 0:01:00right down to the molecular level.
0:01:02 > 0:01:04As a botanist, I am fascinated
0:01:04 > 0:01:08by the massive diversity of edible plants on our planet.
0:01:08 > 0:01:10I'm going to put them under the microscope
0:01:10 > 0:01:15to discover exactly how their biology interacts with our own.
0:01:17 > 0:01:19So, join us, as we seek out
0:01:19 > 0:01:22the most remarkable food stories on the planet
0:01:22 > 0:01:26and reveal the hidden science of our food.
0:01:37 > 0:01:41Flavour makes our food delicious.
0:01:44 > 0:01:49Each flavour is a potent combination of aroma and taste molecules.
0:01:52 > 0:01:56Get that combination right and food tastes heavenly.
0:01:58 > 0:02:00But what is taste?
0:02:02 > 0:02:04Thai cuisine is particularly good
0:02:04 > 0:02:07at exciting our full range of taste receptors...
0:02:08 > 0:02:10..on one plate.
0:02:11 > 0:02:15So, this is a Thai stir-fry and I'm very fond of Thai.
0:02:15 > 0:02:17There is...
0:02:19 > 0:02:23..a bit of fried chicken, lemon, garlic,
0:02:23 > 0:02:27onion - a real sort of explosion of taste.
0:02:27 > 0:02:31And it's really strange to think that all these sensations
0:02:31 > 0:02:34which are going on in my mouth at the moment
0:02:34 > 0:02:37are generated by five simple tastes.
0:02:37 > 0:02:40'In front of me, I've got liquids containing chemicals
0:02:40 > 0:02:42'that will trigger these different tastes.
0:02:42 > 0:02:44'I have no idea which is which.'
0:02:46 > 0:02:47Salty. That's definitely salty.
0:02:49 > 0:02:50Sweet.
0:02:55 > 0:02:59That is sort of bitter, a bit like coffee. And this...
0:03:01 > 0:03:03..is similar but more lemony and makes your mouth pucker up.
0:03:03 > 0:03:05This is sour.
0:03:08 > 0:03:11And this one is really hard to describe.
0:03:11 > 0:03:15This is the taste that has been most recently discovered.
0:03:15 > 0:03:17This is umami.
0:03:17 > 0:03:20The word "umami" is a derivation
0:03:20 > 0:03:24of the Japanese for "a pleasant, savoury taste".
0:03:24 > 0:03:29And it is very, very strange to think that every taste sensation
0:03:29 > 0:03:33you ever have will consist of one or more of these tastes.
0:03:36 > 0:03:40The sensations happen here, on the surface of the tongue.
0:03:42 > 0:03:45Our tongue holds around 4,000 taste buds.
0:03:45 > 0:03:49Inside them are the five taste receptors.
0:03:51 > 0:03:55In humans, this is where the taste begins
0:03:55 > 0:03:58and in this programme, we'll show you how the food we eat
0:03:58 > 0:04:00dazzles each of these receptors.
0:04:02 > 0:04:04But why these five tastes?
0:04:04 > 0:04:08And why is it that some combinations taste vile
0:04:08 > 0:04:10and some taste utterly delicious?
0:04:12 > 0:04:15'We're going to travel the globe, in search of the foods
0:04:15 > 0:04:18'that are particularly good at stimulating each taste...'
0:04:18 > 0:04:20JAMES LAUGHS
0:04:20 > 0:04:22..and in the process,
0:04:22 > 0:04:27uncover how evolution underpins our relationship with food.
0:04:39 > 0:04:42To learn about the most unusual taste,
0:04:42 > 0:04:44I've come to an extraordinary celebration
0:04:44 > 0:04:49of our most popular fruit, which is rich in umami.
0:04:49 > 0:04:51CROWD HUBBUB
0:04:51 > 0:04:53I'm here, in southern Spain,
0:04:53 > 0:04:58with about 20,000 other people to celebrate the tomato.
0:04:58 > 0:05:01CROWD HUBBUB
0:05:01 > 0:05:04THEY CHANT IN SPANISH
0:05:11 > 0:05:16Welcome to La Tomatina and the world's biggest food fight.
0:05:18 > 0:05:20It's been running for over 70 years
0:05:20 > 0:05:23and it's thought it started with a street fight.
0:05:23 > 0:05:25It was so much fun,
0:05:25 > 0:05:29the locals decided to do it again the next year and the next.
0:05:29 > 0:05:32As well as making a perfect food missile,
0:05:32 > 0:05:35tomatoes carry a heavy punch of umami.
0:05:35 > 0:05:39The trouble with being at the back is you get hit a lot.
0:05:41 > 0:05:43But what exactly is umami
0:05:43 > 0:05:47and why does it have such a powerful hold over us?
0:05:49 > 0:05:52The answer lies inside the tomatoes.
0:05:53 > 0:05:57'To get at the umami, I'm going to blitz them,
0:05:57 > 0:06:01'then spin them at high speed in a centrifuge,
0:06:01 > 0:06:06'filter, then finally stir and simmer to concentrate the taste.'
0:06:08 > 0:06:11After all that boiling down, this is all that's left
0:06:11 > 0:06:14and it no longer smells tomatoey at all
0:06:14 > 0:06:17because those volatile flavours have been boiled off.
0:06:17 > 0:06:19And this stuff...
0:06:22 > 0:06:24..doesn't taste tomatoey either.
0:06:24 > 0:06:28It tastes salty, earthy, meaty.
0:06:30 > 0:06:33What my tongue is sensing is a chemical known as glutamate.
0:06:33 > 0:06:35It's an amino acid,
0:06:35 > 0:06:39a type of molecule derived from protein in the tomato.
0:06:39 > 0:06:43Whenever you get a glutamate molecule in food,
0:06:43 > 0:06:45it triggers that umami taste,
0:06:45 > 0:06:49fuelling a desire for more umami-rich food.
0:06:50 > 0:06:53It's our love of the glutamate in tomatoes
0:06:53 > 0:06:56that has made them such an important crop for this region.
0:07:06 > 0:07:10HORN BLARES
0:07:10 > 0:07:13BELL TOLLS
0:07:16 > 0:07:20It's found here, in the ancient oak forests of south-west Spain...
0:07:22 > 0:07:26..home of the chunky local pig known as the "pata negra".
0:07:31 > 0:07:35These pigs roam freely, foraging whatever they can find.
0:07:35 > 0:07:38But their favourite treats are the acorns
0:07:38 > 0:07:41that fall from the oaks every winter.
0:07:43 > 0:07:47And it turns out that pigs and acorns are a match made in heaven.
0:07:48 > 0:07:53Together, they make the most delicious and most expensive
0:07:53 > 0:07:57umami-packed ham in the world - Iberico ham.
0:08:01 > 0:08:04HEN CLUCKS
0:08:04 > 0:08:06It's early morning in January.
0:08:08 > 0:08:12Acorn season is coming to an end and Juana Marquez is preparing
0:08:12 > 0:08:15for one of the most important events of her year.
0:08:18 > 0:08:23In this part of Spain, the annual killing of a pig is a major event.
0:08:23 > 0:08:25It is known as a "matanza",
0:08:25 > 0:08:28and it involves the gathering of an entire family.
0:08:28 > 0:08:33THEY SPEAK IN SPANISH
0:08:44 > 0:08:46PIG SQUEALS
0:08:50 > 0:08:54For Juana's pig, it's as respectful a death as you could hope for.
0:08:55 > 0:09:00It will take the family the entire day to turn 150 kilos of pig
0:09:00 > 0:09:03into enough meat to keep them going all the year.
0:09:06 > 0:09:09But butchering is only the prelude to transforming this meat
0:09:09 > 0:09:14into an incredibly powerful umami-tasting explosion.
0:09:17 > 0:09:20The secret to the intense umami taste begins
0:09:20 > 0:09:23with the extraordinarily thick layer of fat...
0:09:25 > 0:09:29..which comes from the acorns the pigs enjoyed in life.
0:09:33 > 0:09:38The acorn fat from the local oak trees is rich in oleic acid,
0:09:38 > 0:09:41the same fatty acid that's found in olives.
0:09:44 > 0:09:48That's why the locals refer to the pigs as "olives with legs".
0:09:51 > 0:09:55Walking olives that can eat up to ten kilos of acorns a day.
0:10:03 > 0:10:07Most hams end up here, in the darkness of an Iberian cellar.
0:10:08 > 0:10:14This is where biochemistry kicks in and the exquisite umami taste forms.
0:10:15 > 0:10:18The surface of the ham is under constant attack.
0:10:18 > 0:10:22Microbes and oxygen in the air react with the fat on the outside,
0:10:22 > 0:10:24making it yellow and rancid.
0:10:26 > 0:10:28But the meat within is protected.
0:10:29 > 0:10:34The acorn-fed fat layer is so thick it can keep the meat air-free
0:10:34 > 0:10:39for up to three years, much longer than any other ham.
0:10:40 > 0:10:44This allows the natural chemistry locked inside the flesh to unfold.
0:10:49 > 0:10:51The meat starts to cure.
0:10:53 > 0:10:56Over the years, naturally occurring enzymes
0:10:56 > 0:10:58break the proteins in the meat down
0:10:58 > 0:11:01into their basic building blocks - amino acids.
0:11:03 > 0:11:05One of these is the all-important glutamate,
0:11:05 > 0:11:09the molecule responsible for the taste of umami.
0:11:11 > 0:11:14The longer meat cures, the greater the build-up of the glutamate
0:11:14 > 0:11:17and the stronger the taste will become.
0:11:19 > 0:11:25And time is exactly what its thick, fatty case provides each ham.
0:11:25 > 0:11:27By the end, these hams have 50 times
0:11:27 > 0:11:31the glutamate levels of fresh meat...
0:11:31 > 0:11:34HE PLAYS GUITAR
0:11:34 > 0:11:37..making them the world's finest, meatiest,
0:11:37 > 0:11:41most delicious umami-tasting hams.
0:11:48 > 0:11:52It's a taste prized by charcuterie connoisseurs the world over.
0:11:52 > 0:11:55But there's a biological reason
0:11:55 > 0:12:00why we are drawn to the umami flavour of glutamate.
0:12:03 > 0:12:05So, the reason... Mm!
0:12:05 > 0:12:07..why this ham is so delicious
0:12:07 > 0:12:12is because glutamate is one of the building blocks of protein.
0:12:12 > 0:12:14And protein is essential to the building
0:12:14 > 0:12:17and running of every cell in our bodies.
0:12:17 > 0:12:21THEY SING IN SPANISH
0:12:26 > 0:12:29So, what the ham is really saying to me is,
0:12:29 > 0:12:33"Eat me because I will make you big and strong."
0:12:33 > 0:12:36THEY SING IN SPANISH
0:12:41 > 0:12:45And the way it sends that message is, of course, via my taste buds.
0:12:49 > 0:12:52As food enters the mouth, it meets the tongue,
0:12:52 > 0:12:57a seething landscape of muscle, covered by spiky papillae.
0:12:57 > 0:13:01These help move each mouthful of food around.
0:13:03 > 0:13:07As it swirls across the tongue, the food comes across larger,
0:13:07 > 0:13:11dome-shape papillae, and here, we find the taste buds.
0:13:13 > 0:13:15The glutamate enters each bud,
0:13:15 > 0:13:17where it encounters the five taste receptors.
0:13:19 > 0:13:22But the glutamate molecule has a distinctive shape
0:13:22 > 0:13:26that can only activate the umami receptor...
0:13:27 > 0:13:30..sending a signal to the brain that tells us,
0:13:30 > 0:13:34"Mm, that mouthful of food is rather delicious."
0:13:36 > 0:13:39We're hardwired to enjoy the taste of umami
0:13:39 > 0:13:42because it signals the protein we need to build our bodies.
0:13:44 > 0:13:46But we can't survive on protein alone.
0:13:54 > 0:13:58We would grind to a halt without a ready supply of energy.
0:13:59 > 0:14:01So, we have another taste receptor
0:14:01 > 0:14:03that fires off whenever it encounters the chemicals
0:14:03 > 0:14:06that give us a quick energy hit.
0:14:08 > 0:14:09Yum!
0:14:09 > 0:14:11When you bite into a strawberry,
0:14:11 > 0:14:14if you had to pick one word to describe its taste,
0:14:14 > 0:14:16you would probably pick "sweet",
0:14:16 > 0:14:20and that's how our bodies detect the amount of sugar that's in fruit.
0:14:20 > 0:14:24'But sugar and nature seldom comes on its own.
0:14:24 > 0:14:27'It's usually balanced out by another taste -
0:14:27 > 0:14:30'the taste of acid.'
0:14:30 > 0:14:32I'm going to show you that,
0:14:32 > 0:14:35with a fantastically geeky piece of kit here.
0:14:35 > 0:14:42This is a pH meter and it detects how acid solutions are.
0:14:42 > 0:14:46Now, I've got some distilled water here.
0:14:48 > 0:14:49OK.
0:14:50 > 0:14:53And pretty much instantly, bam.
0:14:53 > 0:14:56As I was hoping for, pH 7.
0:14:57 > 0:14:58Perfectly neutral.
0:14:58 > 0:15:00On the other end of the scale,
0:15:00 > 0:15:05I've got this stuff over here - some hydrochloric acid.
0:15:06 > 0:15:09Exactly what I was hoping for. This is pH 1.
0:15:09 > 0:15:12You've got pure water on one end, which is 7,
0:15:12 > 0:15:16and hydrochloric acid as 1, about as acidic as it gets.
0:15:16 > 0:15:18'So, let's test a range of fruit...'
0:15:18 > 0:15:20Let's get some of that juice out.
0:15:20 > 0:15:25'..to find out where they fit on the scale, starting with a strawberry.'
0:15:26 > 0:15:28Yeah, it's going down.
0:15:28 > 0:15:30For something most people describe as sweet,
0:15:30 > 0:15:32this is pretty acidic stuff.
0:15:33 > 0:15:35Look at that. 3.5.
0:15:38 > 0:15:40Right there.
0:15:40 > 0:15:41'The pH meter is measuring
0:15:41 > 0:15:44'the number of hydrogen ions in the fruit,
0:15:44 > 0:15:48'which defines the acidity of each sample.
0:15:48 > 0:15:50'Take a watermelon.'
0:15:50 > 0:15:55Watermelon juice is relatively non-acidic.
0:15:55 > 0:15:575.5, over there.
0:15:58 > 0:16:01'These hydrogen ions trigger our sour receptors,
0:16:01 > 0:16:03'so the sour, let's say, in orange,
0:16:03 > 0:16:05'is actually the taste of acid.'
0:16:05 > 0:16:07Unexpected.
0:16:07 > 0:16:103.5 again.
0:16:10 > 0:16:12'Last up, grapefruit.'
0:16:13 > 0:16:15Huh, 3.52.
0:16:17 > 0:16:19So, this is quite odd.
0:16:19 > 0:16:21All this fruit is the same pH,
0:16:21 > 0:16:27yet people describe strawberries as tasting sweet,
0:16:27 > 0:16:29despite having a similar amount of acid.
0:16:29 > 0:16:34Strawberries have a cunning ability to hide their acidity,
0:16:34 > 0:16:37which begs the question, why produce it in the first place?
0:16:48 > 0:16:52The reason is actually down to a beautiful bit of evolution.
0:17:02 > 0:17:05Strawberry plants have specifically evolved
0:17:05 > 0:17:10this sweet, succulent fruit here to encourage animals to eat them.
0:17:10 > 0:17:12And that's because,
0:17:12 > 0:17:16when these seeds pass through the digestive tract of an animal,
0:17:16 > 0:17:20they're deposited, with a bit of fertiliser, far and wide,
0:17:20 > 0:17:22helping the strawberries' empire grow.
0:17:24 > 0:17:27The thing is, that only works when the seed is fully mature
0:17:27 > 0:17:31and ready to sprout. Until that point, they're not sweet at all.
0:17:31 > 0:17:35In fact, they're packed full of acid, making them taste sour.
0:17:35 > 0:17:37It's an animal deterrent.
0:17:42 > 0:17:45The mild acidic solution from the unripened fruit
0:17:45 > 0:17:49washes over the tongue, stimulating the sour receptors.
0:17:57 > 0:17:59The brain interprets this taste as unpleasant
0:17:59 > 0:18:03and a sign that the food could be spoiled or unfit to eat.
0:18:05 > 0:18:10It's a biological reaction that plants use to their own ends.
0:18:12 > 0:18:16A taste strong and repellent enough to put most animals off.
0:18:17 > 0:18:19'But just at the right moment,'
0:18:19 > 0:18:22when the seeds have matured and are ready to grow,
0:18:22 > 0:18:25it needs to mask this acidity to make it more palatable.
0:18:27 > 0:18:29All the acid is still there,
0:18:29 > 0:18:32but the fruit becomes flooded with sugar,
0:18:32 > 0:18:34produced when hormones from the seeds announce
0:18:34 > 0:18:36they're ready to be eaten.
0:18:36 > 0:18:39The sugars react with other plant molecules
0:18:39 > 0:18:43and make attractive red pigments that say, "Eat me."
0:18:45 > 0:18:47I know you're not supposed to eat them till you've paid, but...
0:18:48 > 0:18:52..that's the point. They are irresistible.
0:18:56 > 0:18:57So, everyone's happy.
0:18:57 > 0:19:01The plant, having sacrificed some sugar, gets its seeds spread...
0:19:05 > 0:19:09..and, in return, the diner gets a sugar reward.
0:19:14 > 0:19:16But the strawberry is sneaky,
0:19:16 > 0:19:20because we may not be getting as much sweet sugar as we think.
0:19:23 > 0:19:27I love strawberries and I also love blueberries.
0:19:27 > 0:19:32But which has more sugar in it? Well, going on taste alone...
0:19:35 > 0:19:38..I'd have said it's the strawberry. But am I right?
0:19:38 > 0:19:43What I'm going to do is squeeze a few of these,
0:19:43 > 0:19:46get a few drops of juice out.
0:19:48 > 0:19:52That's the blueberry done. Now to do a strawberry.
0:19:56 > 0:20:00Now I'm going to use this thing, which is called a refractometer.
0:20:00 > 0:20:03What happens when light passes through any liquid is it gets bent,
0:20:03 > 0:20:07and the more sugar there is in that liquid, the more it gets bent.
0:20:10 > 0:20:13First to be tested for sugar is the blueberry juice.
0:20:15 > 0:20:21And then I can look at the light and I can see a number.
0:20:24 > 0:20:29This gives me the number 13. So, that's 13 for the blueberries.
0:20:29 > 0:20:32Let's do it again with the strawberry.
0:20:38 > 0:20:40Wow, that's surprising!
0:20:40 > 0:20:43Er, that is about 8,
0:20:43 > 0:20:47which means it's nearly half as much sugar per gram
0:20:47 > 0:20:51as there is in the blueberries. I am genuinely surprised by that.
0:20:51 > 0:20:55So, why is it that a strawberry tastes so sweet
0:20:55 > 0:20:57but it doesn't actually contain that much sugar?
0:20:57 > 0:21:00Well, part of the secret of its success...
0:21:00 > 0:21:02HE INHALES ..is its smell.
0:21:05 > 0:21:08Surprisingly, strawberries have altered the way they taste
0:21:08 > 0:21:10using the power of smell.
0:21:12 > 0:21:14Because, alongside the molecules
0:21:14 > 0:21:17that give strawberries their characteristic aroma,
0:21:17 > 0:21:21there lurk other smells with a more crafty purpose.
0:21:23 > 0:21:2836 molecules that seem to boost our taste sensation around sweetness.
0:21:28 > 0:21:31The aroma deceives our brain into thinking
0:21:31 > 0:21:34we're getting a lot more sugar than we actually are.
0:21:37 > 0:21:40Despite the fact that I now know that an awful lot of the sweetness
0:21:40 > 0:21:43I think I'm experiencing in my mouth is actually coming from stuff
0:21:43 > 0:21:48that's going in nose, it hasn't diminished my pleasure at all.
0:21:48 > 0:21:51I still find strawberries deliciously sweet.
0:21:54 > 0:21:56It's a clever trick.
0:21:56 > 0:21:59By boosting how sweet its fruit seems to be,
0:21:59 > 0:22:01the plant needs to give away less sugar,
0:22:01 > 0:22:04while still encouraging us to spread its seeds.
0:22:06 > 0:22:09Food scientists are really interested in discovering
0:22:09 > 0:22:12just how strawberries do what they do,
0:22:12 > 0:22:15because if they could replicate that trick with other foods...
0:22:17 > 0:22:20..then they could produce stuff which tastes satisfyingly sweet,
0:22:20 > 0:22:23but which has far less added sugar.
0:22:39 > 0:22:41Our sense of taste is not just about attracting us
0:22:41 > 0:22:43to what's good to eat and when.
0:22:48 > 0:22:52It's also evolved ways to help us avoid foods that can kill us.
0:22:58 > 0:23:00Take the seeds in fruit.
0:23:00 > 0:23:04Even a few crushed cherry or plum stones can produce
0:23:04 > 0:23:09enough cyanide in the gut to cause paralysis, liver and kidney damage.
0:23:12 > 0:23:17Rhubarb leaves contain the same chemical used to make bleach.
0:23:20 > 0:23:23And uncooked, just five raw kidney beans
0:23:23 > 0:23:26contain enough phytohaemagglutinin
0:23:26 > 0:23:30to bring on vomiting, nausea and diarrhoea.
0:23:36 > 0:23:37Here, in Peru,
0:23:37 > 0:23:41there's an everyday food you might not expect to be a threat.
0:23:46 > 0:23:49Eating is a dangerous business.
0:23:51 > 0:23:53The world is full of things
0:23:53 > 0:23:56that look like they could be interesting to eat.
0:23:58 > 0:24:00But some things might not be such a good idea.
0:24:06 > 0:24:11Take the potato, for instance. Is it friend or foe?
0:24:14 > 0:24:18'The potato plant originated in South America,
0:24:18 > 0:24:22'but most of these wild potatoes would have been left well alone
0:24:22 > 0:24:25'because of their intensely sharp, bitter taste.'
0:24:25 > 0:24:30Potatoes belong to the deadly nightshade family,
0:24:30 > 0:24:34which is packed full of species that are super, super toxic.
0:24:34 > 0:24:38And a toxin that's found in potatoes is called solanine.
0:24:38 > 0:24:42It tastes incredibly bitter. Bad idea to do what I'm doing but...
0:24:45 > 0:24:48I barely punctured this with my teeth
0:24:48 > 0:24:52and already a bitter bloom is going throughout my mouth
0:24:52 > 0:24:54that makes me want to spit it out instantly.
0:24:54 > 0:24:57That's my sense of taste telling me instantly,
0:24:57 > 0:24:59"This is not good for you. Get rid of it."
0:25:02 > 0:25:08Bitter has a crucial role to play in our survival. It's a warning sign.
0:25:11 > 0:25:14Your sense of taste is really a complex chemical detector
0:25:14 > 0:25:18that allows healthy good-for-you foods in and keeps toxic things out.
0:25:21 > 0:25:25The potato plant uses this to protect itself from being eaten.
0:25:27 > 0:25:30See all this green blush over the surface?
0:25:30 > 0:25:33That's evidence it's started to grow and produce solanine.
0:25:33 > 0:25:36They generally are packed in young growing tips
0:25:36 > 0:25:38to help protect the plant even more.
0:25:38 > 0:25:42So, I'm going to try this sprouted potato and it should be even worse.
0:25:45 > 0:25:47Oh, it's... Why did I do that?
0:25:50 > 0:25:53Because the consequences of eating a poison can be so deadly,
0:25:53 > 0:25:58we have 25 types of bitter receptor, all on the lookout for toxins -
0:25:58 > 0:26:01about 20 more than we have for sweet.
0:26:03 > 0:26:07Cos sweet is nice, but bitter can be deadly.
0:26:08 > 0:26:10Can I spit this out? Sorry.
0:26:13 > 0:26:16So, if the original potatoes were poisonous,
0:26:16 > 0:26:20how come the humble spud has become such an important part of our diet?
0:26:22 > 0:26:25Surprisingly, we have the Inca to thank.
0:26:29 > 0:26:32It was in places like here,
0:26:32 > 0:26:34in the mountains of the sacred Incan valley,
0:26:34 > 0:26:38where the poisonous solanine was gradually bred out.
0:26:40 > 0:26:43You know, when people talk about the Inca,
0:26:43 > 0:26:49they tend to mention lost cities and temples and gold,
0:26:49 > 0:26:56but all of this has nothing to do with power or status.
0:26:56 > 0:27:01Everything you see here only exists to grow crops.
0:27:01 > 0:27:04And king amongst them? The potato.
0:27:13 > 0:27:17But for some people who live on the very edge of existence,
0:27:17 > 0:27:21the battle to tame the poisonous spud is still being fought.
0:27:24 > 0:27:29Martin Calisaya and his family live here in this village,
0:27:29 > 0:27:314,000 metres high in the Andes.
0:27:32 > 0:27:35Their lives depend on the potato.
0:27:35 > 0:27:38Almost nothing else will grow at this altitude,
0:27:38 > 0:27:41so spuds provide virtually all their nutrition
0:27:41 > 0:27:45and they grow a huge variety to survive in this harsh environment.
0:27:54 > 0:27:57But even with 100 different varieties,
0:27:57 > 0:27:59a hard frost could spell disaster.
0:28:03 > 0:28:07As a precaution, they grow the hardiest known potato in the world,
0:28:07 > 0:28:10one that can survive even the toughest winter.
0:28:12 > 0:28:14The only downside?
0:28:14 > 0:28:18They're bitter, poisonous and inedible,
0:28:18 > 0:28:21packed full of deadly solanine.
0:28:22 > 0:28:26The incredible thing is, the people from the Andes have developed
0:28:26 > 0:28:31an ingenious technology that turns poison into dinner.
0:28:36 > 0:28:38The trick is to freeze-dry the potatoes
0:28:38 > 0:28:42to remove the toxins and so they can be stored for years.
0:28:44 > 0:28:48In order to get maximum freeze factor, the Quechua need to find
0:28:48 > 0:28:53the very coldest spot and that means going right up there.
0:29:03 > 0:29:07Once a year, the Calisaya family haul their crop
0:29:07 > 0:29:10of inedible, bitter potatoes to a site
0:29:10 > 0:29:14that's 300 metres higher than their village,
0:29:14 > 0:29:17ready to begin a food processing technique
0:29:17 > 0:29:20that dates back around 2,000 years.
0:29:28 > 0:29:30HORSE WHINNIES
0:29:33 > 0:29:38At 4,300 metres, we reach the corral,
0:29:38 > 0:29:41where the potatoes will be processed.
0:29:47 > 0:29:50- BREATHLESSLY:- Growing potatoes the traditional way
0:29:50 > 0:29:53is incredibly labour-intensive.
0:29:53 > 0:29:56But here, you've got to haul this stuff up a mountain
0:29:56 > 0:30:01and, in this thin air, even just the act of spacing them apart,
0:30:01 > 0:30:04so frost gets to them, is killing me.
0:30:10 > 0:30:13At night, the temperature plummets.
0:30:17 > 0:30:22Ice crystals form throughout the potato, rupturing the cell walls.
0:30:25 > 0:30:29This allows the poisonous solanine to leach out.
0:30:35 > 0:30:39After a night out in sub-zero temperatures,
0:30:39 > 0:30:42these guys are frozen solid.
0:30:45 > 0:30:49Up to 80% of the deadly solanine is produced close to the skin,
0:30:49 > 0:30:52and the treading process breaks the skins
0:30:52 > 0:30:54enough to allow an escape route for the poison.
0:30:59 > 0:31:03During the day, when the scorching sun is high in the sky,
0:31:03 > 0:31:04the potatoes begin to thaw.
0:31:07 > 0:31:10With the cell walls ruptured and the skins broken,
0:31:10 > 0:31:14water leaches out, carrying the deadly solanine with it,
0:31:14 > 0:31:19leaving a dried, shrivelled product, known as "chuno".
0:31:21 > 0:31:23This is it. This is the end result.
0:31:23 > 0:31:28And, OK, they might not look irresistible, but this is magic.
0:31:28 > 0:31:33In this form, they can be stored for a decade and still be eaten.
0:31:33 > 0:31:35It is the ultimate in food security.
0:31:40 > 0:31:44So, even if the winter destroys the bulk of their crop,
0:31:44 > 0:31:48Martin and his family will be sure to have enough food.
0:32:11 > 0:32:14The flavour's great. It's kind of floury, like a chestnut,
0:32:14 > 0:32:19like a roasted chestnut, but with kind of smoky, oaky richness to it.
0:32:19 > 0:32:20I've got to say...
0:32:26 > 0:32:29The Quechua have learnt to outsmart
0:32:29 > 0:32:33the incredible bitterness of poisonous potatoes,
0:32:33 > 0:32:37and they've also helped all of us enjoy mash and chips.
0:32:38 > 0:32:41Thanks to them, nearly all the bitter solanine
0:32:41 > 0:32:46has been bred out of the humble spud over hundreds of generations.
0:32:58 > 0:33:00Our sense of taste, then,
0:33:00 > 0:33:03is far more than just about what we enjoy when we eat.
0:33:10 > 0:33:14It's actually a powerful survival mechanism.
0:33:19 > 0:33:21Our sense of taste evolved to guide us
0:33:21 > 0:33:25through a very different world to the one we live in now.
0:33:25 > 0:33:28It was a world where things that tasted sweet were good for us,
0:33:28 > 0:33:30because they gave us instant energy,
0:33:30 > 0:33:32and where things that were bitter were often bad,
0:33:32 > 0:33:34because they might be poisonous.
0:33:34 > 0:33:38In the modern world, of course, it's often the other way round.
0:33:38 > 0:33:40There's another really important taste,
0:33:40 > 0:33:43which is also often confused by the modern world.
0:33:43 > 0:33:47It is a taste which is both an invitation and a warning.
0:33:47 > 0:33:49It is salt.
0:33:53 > 0:33:55We're so used to the taste of salt
0:33:55 > 0:33:59that we sometimes forget just how weird it is.
0:33:59 > 0:34:02Let me show you something which is really quite surprising.
0:34:02 > 0:34:05I'm going to whizz up some coffee.
0:34:05 > 0:34:07BLENDER WHIRRS
0:34:09 > 0:34:11Bit of boiling water.
0:34:13 > 0:34:18I've got a fresh brewed coffee here. Let's give it a go.
0:34:22 > 0:34:24And that is really quite...bitter.
0:34:26 > 0:34:28'This time, I'm going to add a pinch or two of salt
0:34:28 > 0:34:30'to the coffee grounds.'
0:34:36 > 0:34:38Let's give it a go.
0:34:42 > 0:34:45Now, that's quite strange, because that's very different.
0:34:45 > 0:34:47The bitterness has been removed.
0:34:47 > 0:34:50It doesn't actually make it pleasanter, I have to say.
0:34:50 > 0:34:54It just makes it very different because, oddly, what is happening
0:34:54 > 0:34:59is that the sodium in the salt is blocking the bitter receptors.
0:35:02 > 0:35:06And so, it really doesn't taste anything like as bitter as it did
0:35:06 > 0:35:09which, for me, is a shame because I actually like bitter coffee.
0:35:09 > 0:35:12But if you don't, then this is a very neat trick.
0:35:13 > 0:35:16And it's this ability to make food more palatable,
0:35:16 > 0:35:21more delicious, that gives salt such a powerful hold over us.
0:35:22 > 0:35:27And we've also evolved a liking for salt because it's essential to life.
0:35:44 > 0:35:48Billions of years ago, life evolved in the oceans.
0:35:53 > 0:35:56Exactly HOW it began, no-one knows.
0:35:57 > 0:36:00But, as the first simple cells took shape,
0:36:00 > 0:36:04they entrapped a little bit of the salty water inside themselves.
0:36:06 > 0:36:12Today, every cell in our bodies still carries a little salty water,
0:36:12 > 0:36:16a distant echo of our ancient origins in the sea.
0:36:18 > 0:36:20Sea water might taste terrible
0:36:20 > 0:36:26but the taste of a little bit of salt has this universal appeal.
0:36:26 > 0:36:29We like it because we need it.
0:36:29 > 0:36:32Salt is vital for life.
0:36:35 > 0:36:37This biological need has driven us
0:36:37 > 0:36:43to coax salt out of the ocean for thousands of years,
0:36:43 > 0:36:47transforming landscapes, like this corner of Brittany.
0:36:49 > 0:36:53Over time, this salt marsh has been painstakingly sculpted
0:36:53 > 0:36:57into a vast network of evaporation ponds.
0:36:59 > 0:37:05Sophie Bonnet-Questiot is one of 250 salt farmers,
0:37:05 > 0:37:09each tending to their own network of ponds, called a "salina".
0:37:12 > 0:37:18It's the traditional way because it has started in the 9th century.
0:37:18 > 0:37:20The technique is really the same.
0:37:22 > 0:37:24When the tide is high,
0:37:24 > 0:37:29sea water flows 5km from the ocean into a reservoir.
0:37:29 > 0:37:33It's then channelled through a patchwork of ponds,
0:37:33 > 0:37:36each just slightly lower than the last.
0:37:38 > 0:37:40As the water moves down from one pond to the next,
0:37:40 > 0:37:42it becomes more concentrated,
0:37:42 > 0:37:45until it's ten times as salty as it started.
0:37:47 > 0:37:52And then, from the briny water, salt crystals emerge.
0:37:53 > 0:37:57I'm collecting very famous salt of Guerande...
0:37:59 > 0:38:02..that is crystallising at the bottom of the pond,
0:38:02 > 0:38:04directly on clay.
0:38:06 > 0:38:09The highly-prized, beautiful, crystalline flakes of salt
0:38:09 > 0:38:12contain more moisture than common salt,
0:38:12 > 0:38:16which means the taste lingers for much longer.
0:38:19 > 0:38:21And being unrefined, other minerals,
0:38:21 > 0:38:24like calcium and magnesium chloride,
0:38:24 > 0:38:26give it a more complex flavour.
0:38:28 > 0:38:30It's the taste of the sea.
0:38:37 > 0:38:41And this is it. This is the end result.
0:38:42 > 0:38:44After billions of years,
0:38:44 > 0:38:48our bodies still rely on the same basic chemistry
0:38:48 > 0:38:51that evolved in those first blobs of life in the sea.
0:38:59 > 0:39:03Inside the body, salt controls the amount of water in each cell.
0:39:05 > 0:39:08Where there's more salt, water will go.
0:39:10 > 0:39:13It's a process called osmosis.
0:39:13 > 0:39:16It makes cells swell and shrink.
0:39:17 > 0:39:20Elsewhere, the sodium in salt is crucial
0:39:20 > 0:39:22for the functioning of our nerves.
0:39:26 > 0:39:30It's the movement of trillions of sodium ions in our brain
0:39:30 > 0:39:35that allows us to think, move and sense the world around us.
0:39:42 > 0:39:46And these sodium ions also interfere with our taste buds...
0:39:49 > 0:39:52..not just bitter,
0:39:52 > 0:39:53but sweet too.
0:39:56 > 0:39:58As well as the finest salt,
0:39:58 > 0:40:03Brittany is also home to caramel au beurre sale - salted caramel,
0:40:03 > 0:40:06that stuff that's taken the world by storm over recent years.
0:40:06 > 0:40:12We are hardwired to love sugar and hardwired to love salt, separately.
0:40:12 > 0:40:15But when you put them together, something magical happens.
0:40:17 > 0:40:22The sodium in a tiny amount of salt actually makes sugar taste sweeter
0:40:22 > 0:40:26because, alongside our regular sweet receptors,
0:40:26 > 0:40:29we also have some additional receptors that are only activated
0:40:29 > 0:40:33when both sugar and salt are present.
0:40:33 > 0:40:35So, for the maximum sweet sensation,
0:40:35 > 0:40:38seek out the salty taste combinations
0:40:38 > 0:40:41found in ice cream, sweets, chocolates and, of course,
0:40:41 > 0:40:46in the gooey liquid filling inside a thin French pancake -
0:40:46 > 0:40:48a crepe.
0:40:50 > 0:40:53It's not polite, but it's delicious.
0:40:55 > 0:40:57Salt,
0:40:57 > 0:40:59bitter,
0:40:59 > 0:41:01sweet,
0:41:01 > 0:41:02sour
0:41:02 > 0:41:04and umami.
0:41:06 > 0:41:08Together, these five tastes form
0:41:08 > 0:41:12the foundation of our experience of food.
0:41:18 > 0:41:20Because we put food in our mouths,
0:41:20 > 0:41:24we tend to think of all the action happening there, on the taste buds.
0:41:24 > 0:41:26But, in fact, when we experience food,
0:41:26 > 0:41:29we also see it and critically...
0:41:29 > 0:41:31HE INHALES DEEPLY ..we smell it.
0:41:31 > 0:41:35And it's all of that which adds up to what we call flavour.
0:41:35 > 0:41:38COWS MOO
0:41:41 > 0:41:46Curiously, flavour isn't just about taste. It's also about the nose.
0:41:46 > 0:41:49And around this part of the world,
0:41:49 > 0:41:53there's a kind of food that's defined by it's nose - cheese.
0:41:54 > 0:41:58Which is odd, because most cheese starts out life the same way,
0:41:58 > 0:42:00smelling of almost nothing.
0:42:00 > 0:42:03COWS MOO
0:42:03 > 0:42:06So, this is where it all begins.
0:42:07 > 0:42:10And for someone who's used to knowing
0:42:10 > 0:42:12cows on packets in supermarkets,
0:42:12 > 0:42:14it's a dose of reality for me.
0:42:17 > 0:42:21To make cheese, lactic acid is added to fresh cow's milk
0:42:21 > 0:42:22and it's allowed to curdle.
0:42:24 > 0:42:28Then the fragile curds are put into moulds where the whey runs off.
0:42:28 > 0:42:32- You can take more cheese. - OK, bigger scoops.
0:42:34 > 0:42:36Yes, very good.
0:42:36 > 0:42:39'These curds will become the finished cheese,
0:42:39 > 0:42:43'but it begins with very little taste and no smell.
0:42:44 > 0:42:46'And yet, from this beginning,
0:42:46 > 0:42:50'the French produce more than 400 different kinds of cheese...
0:42:53 > 0:42:55'..each with their own unique flavour.'
0:42:57 > 0:42:59Oh, whoa!
0:42:59 > 0:43:01That's intense.
0:43:01 > 0:43:03It's like a furry animal.
0:43:05 > 0:43:10So, how do all these distinctive cheeses end up being so different?
0:43:10 > 0:43:12Well, more than anything else,
0:43:12 > 0:43:16the flavour of each cheese is determined by the way it smells.
0:43:18 > 0:43:21Take a bit of cheese, cover up your nose,
0:43:21 > 0:43:24and even now I can't smell anything, but I can still taste.
0:43:26 > 0:43:29This comte, which is normally incredible,
0:43:29 > 0:43:32it's kind of like eating a salty candle.
0:43:32 > 0:43:35You have this waxy texture, you have a bit of salt,
0:43:35 > 0:43:39a bit of bitterness, but it's like eating in black and white.
0:43:39 > 0:43:42- HE INHALES - And it's incredible.
0:43:42 > 0:43:44The second you uncover your nose,
0:43:44 > 0:43:47this rush of complexity and flavour comes back.
0:43:47 > 0:43:49It's like eating in technicolour.
0:43:49 > 0:43:53The massive difference between the thousands of different types
0:43:53 > 0:43:56of cheese on the planet is all about smell.
0:43:58 > 0:44:01This simple experiment reveals the powerful effect
0:44:01 > 0:44:04that smell can have on the flavour of food.
0:44:04 > 0:44:08'And to better understand how each cheese arrives with its own pong,
0:44:08 > 0:44:13'I'm in Burgundy, where they produce one particularly notorious cheese.'
0:44:14 > 0:44:18It's the cheese known as the king of cheeses,
0:44:18 > 0:44:23Napoleon's favourite and one of the world's smelliest.
0:44:23 > 0:44:26There are stories that this stuff smells so bad
0:44:26 > 0:44:29that it was actually banned from the Paris Metro.
0:44:29 > 0:44:31Nice(!)
0:44:32 > 0:44:37'It's a soft rind-washed cow's cheese and it's called Epoisses.
0:44:39 > 0:44:44'So, what's responsible for making its uniquely powerful smell?
0:44:46 > 0:44:50'For it to develop, the embryonic cheese needs salt,
0:44:50 > 0:44:52'it needs time and it needs bacteria.
0:44:54 > 0:44:57'Each cheese starts its journey of transformation
0:44:57 > 0:44:59'with a specific type of bacteria.
0:45:02 > 0:45:05'But it's how these young cheeses are treated next
0:45:05 > 0:45:07'that creates their flavour and texture.
0:45:09 > 0:45:12'With Epoisses, the rinds are regularly washed
0:45:12 > 0:45:16'with water-down pomace brandy, made from the skins, seeds
0:45:16 > 0:45:19'and stalks of grapes left after winemaking.'
0:45:19 > 0:45:23- It's very fragile.- Yeah. - So, you take it slowly.- OK.
0:45:23 > 0:45:27'The brandy imparts some of its own flavour to the cheese
0:45:27 > 0:45:29'but, most importantly,
0:45:29 > 0:45:32'it affects which bacteria thrive on the cheese.'
0:45:39 > 0:45:44One kind of bacteria is called Arthrobacter arilaitensis,
0:45:44 > 0:45:48which builds long chain molecules that make the rind go orange.
0:45:52 > 0:45:55Another is Brevibacterium linens,
0:45:55 > 0:45:59and these break down the proteins in the cheese into smaller molecules,
0:45:59 > 0:46:02including stinky, sulphur-based compounds
0:46:02 > 0:46:05that give cheese its funky, sweaty aroma.
0:46:07 > 0:46:11It's closely related cousin, Brevibacterium epidermidis,
0:46:11 > 0:46:14can be found growing on human feet,
0:46:14 > 0:46:18giving them THEIR funky, sweaty aroma.
0:46:33 > 0:46:35Voila.
0:46:36 > 0:46:37Ooh!
0:46:40 > 0:46:43They weren't kidding about the way it smells.
0:46:45 > 0:46:48It's intense, it's kind of sulphur-like.
0:46:48 > 0:46:52It's kind of an instant flashback to the rugby socks
0:46:52 > 0:46:56I left in a PE kit once in school for a whole week.
0:47:00 > 0:47:06'Volatile aroma molecules from cheese or feet float into the air
0:47:06 > 0:47:08'and get sucked up into your nose.
0:47:09 > 0:47:13'Each smell compound stimulates a unique combination of receptors
0:47:13 > 0:47:16'that allow us to identify the smell.
0:47:18 > 0:47:22'In the case of Epoisses, it's the smell of stinky feet
0:47:22 > 0:47:25'and it's not particularly pleasant or appetising.
0:47:27 > 0:47:33'So why, if it smells so bad, would anyone put it in their mouth?'
0:47:38 > 0:47:39But...
0:47:41 > 0:47:45..when you eat it, something magical happens.
0:47:45 > 0:47:47The aroma compounds are released in your mouth
0:47:47 > 0:47:50and they waft up the back of your nose
0:47:50 > 0:47:53and they're detected there by the same smell detectors.
0:47:53 > 0:47:56But weirdly, your brain perceives them as very different
0:47:56 > 0:47:58from if you were to smell forward
0:47:58 > 0:48:00and sniff them up the front of your nose.
0:48:03 > 0:48:05It's called backward smelling.
0:48:07 > 0:48:09Rather than simply smelling the pong,
0:48:09 > 0:48:12the brain now combines the smell with the creamy taste
0:48:12 > 0:48:16it's experiencing on the tongue at the same time.
0:48:16 > 0:48:19This combination of taste and smell
0:48:19 > 0:48:21'has a dramatic effect
0:48:21 > 0:48:25'on how we perceive a particular odour molecule.
0:48:25 > 0:48:29'And for the full effect, always eat the rind,
0:48:29 > 0:48:32'since this is where many of the smells lie.'
0:48:32 > 0:48:33This stuff...
0:48:34 > 0:48:39..no longer is pungent and kind of animalic, like your body.
0:48:39 > 0:48:44It's suddenly sharp, garlicky, eggy.
0:48:44 > 0:48:48It's just warming, comforting deliciousness.
0:48:57 > 0:49:00This is the full flavour experience.
0:49:02 > 0:49:06Only by combining taste and backwards smells in our brain,
0:49:06 > 0:49:10so we unlock the food's full flavour potential.
0:49:16 > 0:49:19Breathe normally in there.
0:49:19 > 0:49:23'We may have only five types of taste receptors on our tongue,
0:49:23 > 0:49:25'but our noses are packed
0:49:25 > 0:49:28'with around 400 different smell detectors.
0:49:28 > 0:49:33'I'm testing how good my smell detectors are by sniffing aromas
0:49:33 > 0:49:37'extracted from a mystery meal, one of the nation's favourites.'
0:49:37 > 0:49:39Whoa, that one's strong.
0:49:42 > 0:49:45This one, for some reason, is making me think of wet mackintoshes.
0:49:47 > 0:49:50'The twist is, I'm not going to eat even a spoonful.'
0:49:50 > 0:49:52Quite aromatic.
0:49:52 > 0:49:56'Instead, I'm inhaling wafts of the individual aroma molecules
0:49:56 > 0:49:58'that make up this mystery meal.'
0:49:58 > 0:50:01It smells almost faecal. I'm trying to work out what it is.
0:50:01 > 0:50:03That's weird.
0:50:05 > 0:50:07Almost aniseedy.
0:50:09 > 0:50:12Smells a damp basement smell.
0:50:14 > 0:50:16Not like you can say that's lemon or that's...
0:50:18 > 0:50:20..pine cone or...
0:50:22 > 0:50:23They're sort of spicy.
0:50:23 > 0:50:26'It's only when all the smells are brought together
0:50:26 > 0:50:30'at the end of the test that I can finally hazard a guess.'
0:50:32 > 0:50:34- Would you like to smell this one? - OK, yeah.- Yeah.
0:50:36 > 0:50:37Whoa, that's strong.
0:50:37 > 0:50:41So, that is definitely curry and it smells like...
0:50:41 > 0:50:45- Is that chicken korma? - Yes, exactly.
0:50:45 > 0:50:51We broke down all the aroma components of this curry
0:50:51 > 0:50:54and you smell them one after the other.
0:50:54 > 0:50:56- And I couldn't put them all together.- Yeah.
0:50:56 > 0:51:00There are many spices so you can get many spicy notes, many meaty notes.
0:51:00 > 0:51:05- Some strange notes, like rose, like potato.- OK, yeah.
0:51:05 > 0:51:08- And the pigsty.- Maybe it was the pigsty I was smelling
0:51:08 > 0:51:10- at the beginning.- Sweaty. - Yeah.- Yeah.
0:51:10 > 0:51:14Very, very odd, having them as distinctive things
0:51:14 > 0:51:16and then trying to add them up to something.
0:51:16 > 0:51:18I would never, ever have guessed that was chicken korma.
0:51:18 > 0:51:21And yet, when I smell that, I know straightaway it's chicken korma.
0:51:21 > 0:51:23- It just smells like it.- Yep.
0:51:23 > 0:51:26It's one of the things I'm quite familiar with. Yeah.
0:51:29 > 0:51:33This experiment reveals how our noses help us enjoy food.
0:51:37 > 0:51:40Rather than singling out individual notes...
0:51:41 > 0:51:46..all the individual aromas come together to form one unified,
0:51:46 > 0:51:50instantly identifiable and delicious pong.
0:51:57 > 0:52:01Using just 400 different smell receptors...
0:52:02 > 0:52:04..our noses are so powerfully tuned,
0:52:04 > 0:52:07that it's been estimated we can identify
0:52:07 > 0:52:09a trillion different smells.
0:52:12 > 0:52:14Like pizza,
0:52:14 > 0:52:16roast chicken
0:52:16 > 0:52:18or an oak-aged Bordeaux.
0:52:26 > 0:52:30In our search for evermore delicious and satisfying things
0:52:30 > 0:52:32to indulge our senses,
0:52:32 > 0:52:35we've created extraordinary processes
0:52:35 > 0:52:40that alter the taste, texture and aroma of our food.
0:52:43 > 0:52:47But one has profoundly changed the course of civilisation.
0:52:48 > 0:52:52It has transformed our experience and our enjoyment of food.
0:52:52 > 0:52:54It is, of course, cooking.
0:52:58 > 0:53:02There's evidence our remote ancestors began cooking food
0:53:02 > 0:53:05at least 400,000 years ago.
0:53:06 > 0:53:10And from the start, they were unwittingly triggering, in our food,
0:53:10 > 0:53:13one of the most complex chemical reactions on Earth.
0:53:15 > 0:53:18Now, this is a truly wonderful piece of meat.
0:53:18 > 0:53:22It's a local speciality, known as "bistecca Fiorentina".
0:53:22 > 0:53:25In its raw state, like this... HE INHALES
0:53:25 > 0:53:27..it really doesn't smell of anything very much.
0:53:27 > 0:53:29But put it on the grill over there,
0:53:29 > 0:53:32something truly wondrous will happen.
0:53:32 > 0:53:36It's called the Maillard reaction, named after a Frenchman,
0:53:36 > 0:53:39but I prefer to call it the "science of the sizzle".
0:53:44 > 0:53:48- Fantastic. You don't put salt? - No, no.- No?
0:53:48 > 0:53:51- No, no.- Oil?- No, nothing.
0:53:53 > 0:53:56The key to unlocking the flavour in the meat
0:53:56 > 0:54:00is the smells that will be generated by the Maillard reaction,
0:54:00 > 0:54:04and you can actually see it happening right before your eyes.
0:54:10 > 0:54:12So, all this lovely brown stuff you can see over here,
0:54:12 > 0:54:15that is the results of the Maillard reaction.
0:54:18 > 0:54:20It starts off simply enough.
0:54:20 > 0:54:23In the intense heat, the building blocks of protein,
0:54:23 > 0:54:25the amino acids,
0:54:25 > 0:54:28react with naturally occurring sugars in the meat.
0:54:28 > 0:54:31And the beauty of the Maillard reaction is that,
0:54:31 > 0:54:34once it kicks off, everything goes completely crazy.
0:54:39 > 0:54:42The reaction becomes more and more complex
0:54:42 > 0:54:46and intensifies as the products of each reaction
0:54:46 > 0:54:48get involved in their own reactions.
0:54:50 > 0:54:53Eventually, the whole thing cascades wildly
0:54:53 > 0:54:56and generates thousands of different molecules.
0:55:03 > 0:55:06Lots of lovely aroma molecules that I am now...
0:55:06 > 0:55:09HE INHALES ..hungrily hovering up.
0:55:14 > 0:55:17Smells absolutely fantastic now, I have to say.
0:55:17 > 0:55:19Complete transformation from that piece of meat, as it was,
0:55:19 > 0:55:23- to what it is now. - Ora, sale grosso.
0:55:26 > 0:55:28- Oil.- OK. Olive oil, splash on.
0:55:34 > 0:55:36- It's perfect.- Perfect.- Perfect.
0:55:43 > 0:55:45And it's not just about meat.
0:55:47 > 0:55:49Baking bread,
0:55:49 > 0:55:51roasting coffee,
0:55:51 > 0:55:54frying onions and garlic.
0:55:57 > 0:56:00If it smells good when you cook,
0:56:00 > 0:56:03the secret chemist inside you is actually analysing
0:56:03 > 0:56:06the results of a Maillard reaction...
0:56:10 > 0:56:15..a reaction so complex it takes a whole textbook to describe it.
0:56:15 > 0:56:17THEY CHEER
0:56:24 > 0:56:26Our understanding of food
0:56:26 > 0:56:31and how it seduces our senses is deepening all the time.
0:56:33 > 0:56:36In the past, when eating the wrong thing could be a threat,
0:56:36 > 0:56:40our senses guided us to swallow what was nourishing
0:56:40 > 0:56:43and to spit out what might harm us.
0:56:45 > 0:56:46'For modern humans, though,
0:56:46 > 0:56:50'taste is no longer merely a guide to survival.
0:56:53 > 0:56:55'Today, we transform food in ways
0:56:55 > 0:56:59'our ancestors would never have recognised...
0:57:00 > 0:57:03'..to create combinations that stimulate our eyes,
0:57:03 > 0:57:06'noses and all our taste buds...
0:57:07 > 0:57:11'..to create the ultimate mouthful of flavour.'
0:57:11 > 0:57:13THEY CHEER
0:57:13 > 0:57:18These days, taste is mainly about pleasure, the enjoyment in food.
0:57:18 > 0:57:22And it's that enjoyment which brings communities and families together.
0:57:22 > 0:57:26It's because we really understand what makes food work
0:57:26 > 0:57:29that we're able to create unusual combinations,
0:57:29 > 0:57:31really make our taste buds zing.
0:57:33 > 0:57:37Next time, we explore why we have food on the brain.
0:57:38 > 0:57:43We discover how it ignites powerful, irresistible cravings in us...
0:57:43 > 0:57:45That is truly delicious!
0:57:45 > 0:57:47..and sometimes disgust,
0:57:47 > 0:57:50why we welcome pain
0:57:50 > 0:57:54and have learnt to love the hottest food on the planet.
0:57:57 > 0:58:00Can science affect your perception of food?
0:58:00 > 0:58:02How instinctive are you?
0:58:02 > 0:58:04To find out more about the foods you eat,
0:58:04 > 0:58:07go to the BBC website on the screen
0:58:07 > 0:58:10and follow the links to the Open University.