0:00:04 > 0:00:08'How often do you stop and really think about your food?'
0:00:08 > 0:00:11Look at all this lovely fat and sugar.
0:00:11 > 0:00:13Yummy.
0:00:13 > 0:00:16'Do you ever wonder why you eat what you eat,
0:00:16 > 0:00:18'What 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 > 0:00:28I trained as a medical doctor and 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 > 0:00:41..together we have taken over
0:00:41 > 0:00:43the country's leading food science lab...
0:00:45 > 0:00:49..to deconstruct some of our favourite foods...
0:00:49 > 0:00:50It's all sunk to the bottom.
0:00:50 > 0:00:54..and to reveal some truly remarkable secrets.
0:00:54 > 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 > 0:01:06As a botanist, I am fascinated by the massive diversity
0:01:06 > 0:01:08of edible plants on our planet.
0:01:08 > 0:01:11I'm going to put them under the microscope to discover
0:01:11 > 0:01:14exactly how their biology interacts with our own.
0:01:17 > 0:01:19So join us as we seek out
0:01:19 > 0:01:23the most remarkable food stories on the planet
0:01:23 > 0:01:25and reveal the hidden science of our food.
0:01:41 > 0:01:43We humans are peculiar.
0:01:43 > 0:01:45We eat foods no other animal would eat.
0:01:51 > 0:01:55On average, we spend 67 minutes a day eating.
0:01:56 > 0:01:58Which, over a lifetime,
0:01:58 > 0:02:01adds up to nearly three and a half years at the table...
0:02:03 > 0:02:06..but we spend even more time thinking about food.
0:02:08 > 0:02:12When we're hungry, food begins to dominate our thoughts
0:02:12 > 0:02:15and, of course, our brains.
0:02:15 > 0:02:18And what's remarkable is we're beginning to understand exactly
0:02:18 > 0:02:22why certain foods create such cravings in us all.
0:02:23 > 0:02:25In this episode
0:02:25 > 0:02:28we'll be revealing how food really works on your brain,
0:02:28 > 0:02:33why we find some foods unbelievably delicious and delightful,
0:02:33 > 0:02:36but why others, well, they're quite frankly disgusting.
0:02:38 > 0:02:43This is the science that explains why food has such tremendous power
0:02:43 > 0:02:45over us and our behaviour.
0:02:53 > 0:02:57To start, how can we get a measure of how much our brains love or hate
0:02:57 > 0:02:58a particular food?
0:03:01 > 0:03:04Rather than eat, I'm going to use sight and smell alone to measure
0:03:04 > 0:03:09something we can't stop ourselves producing when we're around food -
0:03:09 > 0:03:10saliva.
0:03:10 > 0:03:15So, what I've got here is a little swab and it weighs 0.68g.
0:03:15 > 0:03:16Put that in there...
0:03:16 > 0:03:19and I've got what I'm told is a delicious meal underneath here
0:03:19 > 0:03:21so let's have a look.
0:03:21 > 0:03:23It doesn't smell delicious, I have to say.
0:03:23 > 0:03:25Oh, God! That's revolting.
0:03:25 > 0:03:28HE COUGHS It looks completely rancid,
0:03:28 > 0:03:30I have no idea what it is.
0:03:30 > 0:03:33'This is actually a delicacy in China.
0:03:33 > 0:03:36'It's a preserved egg called a century egg.'
0:03:36 > 0:03:40It reeks of ammonia and hydrogen sulphide, the smell of rotten eggs.
0:03:42 > 0:03:44So what will the saliva test reveal?
0:03:44 > 0:03:48In theory, the more I like the food, the more I should salivate.
0:03:49 > 0:03:52So, let's see what effect that has had on my...
0:03:52 > 0:03:53saliva.
0:03:56 > 0:03:590.88, so it's gone up a little bit.
0:03:59 > 0:04:01I think that was in anticipation of something
0:04:01 > 0:04:04which turned out to be utterly revolting.
0:04:04 > 0:04:06I'm not producing much saliva.
0:04:06 > 0:04:09I really don't want to eat this.
0:04:09 > 0:04:10Right.
0:04:11 > 0:04:14Dish number two, which I am also told is delicious,
0:04:14 > 0:04:16although by now I'm deeply suspicious.
0:04:18 > 0:04:19Smells better anyway.
0:04:19 > 0:04:21OK, what is it?
0:04:21 > 0:04:23And it is chocolate cake, hurrah!
0:04:26 > 0:04:32Now, yeah, that smells nice and I can feel those...
0:04:32 > 0:04:35saliva flowing. Let's see if that has any measurable effect.
0:04:35 > 0:04:40Yeah, we are up to 1.83 this time, so lots of saliva there.
0:04:41 > 0:04:44For one of my favourite foods, chocolate,
0:04:44 > 0:04:46I produced about six times as much saliva.
0:04:47 > 0:04:53So this shows just how much the look and smell of food alone can fire up
0:04:53 > 0:04:56our brains and juice up our salivary glands.
0:04:56 > 0:04:59But why do we do it?
0:04:59 > 0:05:03Well, producing saliva helps us start digesting our food the moment
0:05:03 > 0:05:05it reaches our mouths.
0:05:05 > 0:05:10And that's because saliva contains digestive enzymes.
0:05:10 > 0:05:14And it's perhaps no surprise that I drooled over chocolate because the
0:05:14 > 0:05:17chemistry of chocolate makes it the world's most craved food.
0:05:24 > 0:05:29We Brits eat an average of almost 7.5 kilos of chocolate every year.
0:05:32 > 0:05:35The mere sight of it may be triggering feelings of desire
0:05:35 > 0:05:36in your brain right now.
0:05:42 > 0:05:46But just how does it create such strong cravings?
0:06:08 > 0:06:12I've come to Peru to discover how we transform chocolate from raw,
0:06:12 > 0:06:15bitter beans into bars of deliciousness.
0:06:18 > 0:06:21I want to understand exactly why we crave it so much.
0:06:33 > 0:06:36It's especially strange because in its raw state
0:06:36 > 0:06:39the cocoa plant is not at all what you might expect.
0:06:44 > 0:06:47Wow! Look at that.
0:06:47 > 0:06:51You break open this thick husk and you've got sticky ivory pulp
0:06:51 > 0:06:52that is...
0:06:52 > 0:06:54It is truly delicious.
0:06:54 > 0:06:59It has this incredible tropical flavour that's halfway
0:06:59 > 0:07:03between lemonade and a custard apple, if you've ever had that,
0:07:03 > 0:07:05sweet, acidic, sticky.
0:07:07 > 0:07:09I'm sorry for being gross, but...
0:07:10 > 0:07:14The bit that chocolate's made out of is the bean on the inside,
0:07:14 > 0:07:16if you were to spit it out.
0:07:16 > 0:07:21It's amazing that anyone thought that beneath sticky, sweet,
0:07:21 > 0:07:22delicious flesh,
0:07:22 > 0:07:26the rock hard super-bitter bean on the inside could make good eating.
0:07:29 > 0:07:31The processing of chocolate begins
0:07:31 > 0:07:33as soon as the pods are off the plant.
0:07:36 > 0:07:38They're left to ferment in their own juices...
0:07:39 > 0:07:43..where naturally occurring yeast breaks down sugar into alcohol
0:07:43 > 0:07:46which, in turn, helps remove the bitter alkaloids from the beans.
0:07:48 > 0:07:52Then the beans are dried and they're still raw and quite bitter,
0:07:52 > 0:07:54nothing like the chocolate we know and love.
0:08:02 > 0:08:03What happens next will soon get
0:08:03 > 0:08:06my grey matter crackling with excitement.
0:08:07 > 0:08:10The beans are put in a kind of oven.
0:08:10 > 0:08:12What this does is it roasts the beans
0:08:12 > 0:08:15and that's really key to bringing out that kind of
0:08:15 > 0:08:20toasty, warm, characteristically chocolaty flavour.
0:08:20 > 0:08:22120 degrees, there they go.
0:08:25 > 0:08:28All this processing creates hundreds of new chemical compounds
0:08:28 > 0:08:30in the chocolate beans.
0:08:32 > 0:08:36And it's converting the otherwise odourless compounds into volatile
0:08:36 > 0:08:40aroma-bearing ones, which begins to explain chocolate's popularity.
0:08:42 > 0:08:46The roasted bean's still got these very fine thin shells on.
0:08:47 > 0:08:51They're going in here and you can actually see all the shells
0:08:51 > 0:08:56wafting up and, for the first time, you can suddenly smell chocolate.
0:08:56 > 0:08:58It's...
0:08:58 > 0:08:59Oh, it's good. It's really good.
0:09:04 > 0:09:09The comforting aroma of chocolate actually comes from 25 different
0:09:09 > 0:09:11smell molecules,
0:09:11 > 0:09:15like 3-methyllbutannic acid
0:09:15 > 0:09:17and dimethyl trisulphide.
0:09:18 > 0:09:21And the weird thing is, on their own,
0:09:21 > 0:09:24they're more reminiscent of body odour and cooked cabbage.
0:09:25 > 0:09:28But with so many types of molecules
0:09:28 > 0:09:31wafting out of the cocoa beans and assaulting our noses,
0:09:31 > 0:09:33our brains just can't separate them out.
0:09:34 > 0:09:39Instead, one combined glorious smell emerges, delicious chocolate.
0:09:44 > 0:09:46But aroma is just part of the story.
0:09:53 > 0:09:56Cocoa beans are incredibly rich in fat,
0:09:56 > 0:10:00roughly like 50%, and if you take a whole bunch of them and squish that
0:10:00 > 0:10:04fat out and get it to cool down to room temperature, you get this.
0:10:04 > 0:10:06This is cocoa butter.
0:10:08 > 0:10:12Cocoa butter is just one of many different types of fat,
0:10:12 > 0:10:14each with unique characteristics,
0:10:14 > 0:10:17which create pure pleasure when teamed with the right food.
0:10:19 > 0:10:22Imagine toast without butter,
0:10:22 > 0:10:25frying without oil
0:10:25 > 0:10:28or ice cream without, well, cream.
0:10:29 > 0:10:32Fat transforms our enjoyment of food and for good reason.
0:10:34 > 0:10:37Before agriculture, fat was a critical source of energy
0:10:37 > 0:10:39to our ancestors.
0:10:39 > 0:10:43So our brains may well have evolved to reward us with feelings
0:10:43 > 0:10:44of pleasure when we ate it.
0:10:47 > 0:10:52And we now know exactly where in the brain this pleasure is felt -
0:10:52 > 0:10:56regions like the lateral hypothalamus and the amygdala.
0:10:59 > 0:11:03We've even seen that the higher the level of fat in a food,
0:11:03 > 0:11:05the more active these parts of the brain become.
0:11:08 > 0:11:12Now, there's one national delicacy almost guaranteed
0:11:12 > 0:11:14to fire up your brain -
0:11:14 > 0:11:16Cornish clotted cream.
0:11:16 > 0:11:21It's a whopping 60% fat, the creamiest of all creams.
0:11:22 > 0:11:24But it may not have originated in Cornwall at all.
0:11:36 > 0:11:38I've come to Afyon in Turkey
0:11:38 > 0:11:41in search of the origin of clotted cream.
0:11:42 > 0:11:46It's one of the richest, most melt-in-the-mouth dishes in the world.
0:11:49 > 0:11:53But I'm also here to discover just why this type of fat has such
0:11:53 > 0:11:55a powerful effect on our brains.
0:11:56 > 0:12:01The fat I'm interested in is made from the milk of these animals -
0:12:01 > 0:12:02water buffalo.
0:12:05 > 0:12:09To make the creamiest fat, you need extremely rich milk,
0:12:09 > 0:12:11and to make that, water buffalo
0:12:11 > 0:12:13need to eat something pretty extraordinary.
0:12:22 > 0:12:25These are the poppy fields that surround Afyon.
0:12:29 > 0:12:32At the height of summer, the seed heads are harvested for the legal
0:12:32 > 0:12:35production of opiate-based medicines like morphine.
0:12:36 > 0:12:40What's left behind becomes fodder for the buffalo.
0:12:40 > 0:12:42Hi there.
0:12:42 > 0:12:45Along with hay, this is what these buffalo are eating.
0:12:45 > 0:12:48It's what's left over when they've taken the poppy,
0:12:48 > 0:12:52they've extracted the opium and sent it off to be turned into morphine
0:12:52 > 0:12:54and other painkillers
0:12:54 > 0:12:56and this is really what remains.
0:12:56 > 0:12:59Now, there's not going to be any opiate left inside it but it's said
0:12:59 > 0:13:02to be extremely nutritious
0:13:02 > 0:13:05and the reason they feed it to buffalo is it's said
0:13:05 > 0:13:07to add to the flavour, but particularly the sort of...
0:13:07 > 0:13:09the richness, the fatness,
0:13:09 > 0:13:11the oiliness of the milk.
0:13:14 > 0:13:16There you go.
0:13:17 > 0:13:18Oh, blimey!
0:13:20 > 0:13:25The poppy is packed full of natural oils and fats and some of this
0:13:25 > 0:13:27ends up in the buffalo's milk.
0:13:27 > 0:13:29Let's give it a go.
0:13:29 > 0:13:31HE GROANS
0:13:31 > 0:13:32Nothing.
0:13:32 > 0:13:34Sorry about that.
0:13:34 > 0:13:35Yeah, OK.
0:13:36 > 0:13:38HE LAUGHS
0:13:38 > 0:13:40I think I'll leave it to you.
0:13:41 > 0:13:44The milk produced by buffalo is extremely rich
0:13:44 > 0:13:46and has twice the fat of cow's milk.
0:13:47 > 0:13:51So here we go. That's the product of a bit of hard work - not by me,
0:13:51 > 0:13:53I have to say.
0:13:54 > 0:13:58This rich, oily milk will be turned into an ancient version
0:13:58 > 0:14:01of clotted cream called kaymak.
0:14:01 > 0:14:04- Merhaba!- Merhaba.
0:14:04 > 0:14:06This is where the magic happens, is it?
0:14:07 > 0:14:10Milk has a very particular chemistry.
0:14:11 > 0:14:13It's mainly fat and water,
0:14:13 > 0:14:16which together form what's called an emulsion.
0:14:17 > 0:14:22The fat is dispersed throughout the water in tiny globules.
0:14:22 > 0:14:25When it's heated, some of the water is evaporated off,
0:14:25 > 0:14:27leaving a higher concentration of fat.
0:14:28 > 0:14:32These globules become sticky and some bind together to form
0:14:32 > 0:14:34a delicate mesh on the surface.
0:14:36 > 0:14:40It's now a matter of letting it stand and gently cooking again until
0:14:40 > 0:14:41it's ready.
0:14:45 > 0:14:47Now, this is a very traditional way of making clotted cream and,
0:14:47 > 0:14:51in fact, it's pretty much how they make it down in Devon and Cornwall
0:14:51 > 0:14:54and that is perhaps because there is a link.
0:14:54 > 0:14:58It's said that the Phoenicians around 2,000 years ago
0:14:58 > 0:15:00brought this technique from this part of the world.
0:15:00 > 0:15:02They went to Cornwall in search of tin,
0:15:02 > 0:15:04what they left behind was clotted cream.
0:15:06 > 0:15:10So the great Cornish delicacy could have started life here in Turkey.
0:15:14 > 0:15:19This is kind of the end product, right? You stick your hands in.
0:15:19 > 0:15:21She's invited me to stick my hand in as well. OK.
0:15:21 > 0:15:23I have washed my hands, I promise you.
0:15:27 > 0:15:30So it's, erm, like sort of the finest soap.
0:15:30 > 0:15:33You can imagine sort of, you know, washing in it almost.
0:15:33 > 0:15:36It's got a very lovely sort of silky texture to it.
0:15:36 > 0:15:38OK, so I think...
0:15:38 > 0:15:42'Kaymak is 60% fat, three times that of single cream.
0:15:42 > 0:15:46'The way it feels on the tongue drives our brains wild.'
0:15:47 > 0:15:51So what is it that kaymak has that other foods are missing?
0:15:53 > 0:15:57Why is it so much more seductive than, say, butter?
0:15:59 > 0:16:03The way that kaymak is made obviously determines its structure
0:16:03 > 0:16:07and its structure in turn will influence what it feels like
0:16:07 > 0:16:09in my mouth, so let's give it a go.
0:16:10 > 0:16:12Oh, it's very smooth and creamy.
0:16:12 > 0:16:15I can feel it flowing across my tongue.
0:16:17 > 0:16:21The ease with which something flows is also known as its viscosity
0:16:21 > 0:16:23and that is something you can measure.
0:16:28 > 0:16:32This machine is a rheometer.
0:16:32 > 0:16:36It accurately measures viscosity at certain temperatures and pressures.
0:16:40 > 0:16:43And viscosity turns out to be the secret behind why
0:16:43 > 0:16:46kaymak is so good to eat.
0:16:48 > 0:16:52What is really striking about this graph is the collapse here at around
0:16:52 > 0:16:5624 degrees, when it goes from being sort of thick and solid and turns
0:16:56 > 0:16:59into a liquid. We did the same test with another fat,
0:16:59 > 0:17:02in this case it was butter and, as you can see there,
0:17:02 > 0:17:07butter begins to change at around 24 degrees but it's a much more gradual
0:17:07 > 0:17:11change and that may help explain why butter is not one of those things
0:17:11 > 0:17:14you like to take out of the fridge and sort of wolf down.
0:17:18 > 0:17:24Kaymak melts and flows more quickly over the tongue than butter,
0:17:24 > 0:17:26making it feel smooth.
0:17:27 > 0:17:28Dig in!
0:17:28 > 0:17:32'And it's this smoothness that our brains respond to,
0:17:32 > 0:17:35'via special receptors on our tongues.'
0:17:35 > 0:17:36Some kaymak.
0:17:40 > 0:17:42If you take a close look at your tongue,
0:17:42 > 0:17:47you'll see it's covered with lots of little bumps called papillae.
0:17:47 > 0:17:48On the surface of these papillae,
0:17:48 > 0:17:52you have taste receptors, but you also have touch receptors.
0:17:53 > 0:17:56Now if you eat something which is fat,
0:17:56 > 0:18:00then that fat contains tiny little globules which are so small,
0:18:00 > 0:18:02only a few microns across,
0:18:02 > 0:18:07that your touch receptors don't perceive it as different particles,
0:18:07 > 0:18:10they just see it as one thing, smoothness.
0:18:13 > 0:18:16Since fat triggers touch receptors on the tongue,
0:18:16 > 0:18:20you might think that the signals end up in the touch region of the brain.
0:18:26 > 0:18:27And indeed they do.
0:18:27 > 0:18:32But the signals also go to the area for taste so, oddly enough,
0:18:32 > 0:18:38the brain perceives the feel, the texture of fat as a taste,
0:18:38 > 0:18:43which helps explain why the texture of some fats is so important when
0:18:43 > 0:18:46it comes to creating these wonderful feelings
0:18:46 > 0:18:48in the pleasure centres of our brains.
0:18:48 > 0:18:50Thank you very much. Bye-bye!
0:18:58 > 0:19:03Chocolate, too, can drive the pleasure centres of our brains wild
0:19:03 > 0:19:06with its creamy, high-fat content.
0:19:08 > 0:19:10But until the 16th century,
0:19:10 > 0:19:12we wouldn't have given it a second thought.
0:19:16 > 0:19:19When the Spanish Conquistadores first arrived in the Americas,
0:19:19 > 0:19:22they found the indigenous people drinking a bitter mixture
0:19:22 > 0:19:25made from cocoa beans.
0:19:25 > 0:19:28The Spanish thought of adding one more ingredient that would make for
0:19:28 > 0:19:30something far more appealing.
0:19:30 > 0:19:31And they were right.
0:19:33 > 0:19:36That ingredient was lots of sugar.
0:19:36 > 0:19:40The addition of sugar to this mix is so crucial
0:19:40 > 0:19:43to our enjoyment of chocolate, because in nature
0:19:43 > 0:19:47sugar and fat are very rarely found together,
0:19:47 > 0:19:49at least in high concentrations.
0:19:52 > 0:19:55Fruits like strawberries are packed full of sugar.
0:19:58 > 0:20:01If you want fat, certain cuts of meat will give you a hefty dose...
0:20:02 > 0:20:07..but if you want a mixture of both, and in relatively equal measure,
0:20:07 > 0:20:11there's just one place in nature that that can be found.
0:20:11 > 0:20:15It's only really in breast milk where you end up with this perfect fusion
0:20:15 > 0:20:21of 50% of the calories coming from sugar and 50% coming from fat.
0:20:22 > 0:20:26So our craving for chocolate goes back to the first moments of life...
0:20:28 > 0:20:29..your very first meal.
0:20:31 > 0:20:33And that craving stays with us.
0:20:38 > 0:20:42If you think about almost all the foods that just drive people crazy,
0:20:42 > 0:20:46you know, cookies, doughnuts, cheesecake, ice cream,
0:20:46 > 0:20:48if you look at the recipes,
0:20:48 > 0:20:52almost all of them have a rough 50/50 split in terms of calories
0:20:52 > 0:20:57between sugar and fat. It's that golden formula that just basically
0:20:57 > 0:20:59sends off all the pleasure signals in our brain,
0:20:59 > 0:21:01making food just irresistible.
0:21:02 > 0:21:06It's a comforting chemical composition that we biologically
0:21:06 > 0:21:08are set up to love.
0:21:13 > 0:21:18So what exactly are chocolate and other fat and sugar-filled foods
0:21:18 > 0:21:23with that magic 50/50 ratio actually doing to our brains?
0:21:23 > 0:21:27Why do these foods become almost addictive?
0:21:28 > 0:21:33Even as I look at all this lovely fat and sugar,
0:21:33 > 0:21:35I'm beginning to drool.
0:21:35 > 0:21:38My own weakness is our very own version of kaymak...
0:21:40 > 0:21:43..clotted cream at the heart of a cream tea.
0:21:43 > 0:21:46I've even got a little bit of a shake.
0:21:46 > 0:21:49Our desire to eat as something as delicious as a cream tea...
0:21:52 > 0:21:57..and why we crave it over and over again has been mapped in the brain.
0:21:57 > 0:21:58Mmm!
0:22:04 > 0:22:07Now I'm getting sensory overload.
0:22:07 > 0:22:09It releases a whole
0:22:09 > 0:22:10host of flavours in my mouth.
0:22:12 > 0:22:17There's also loads of things clicking off in my brain,
0:22:17 > 0:22:20and I'll show you here just what's going on.
0:22:20 > 0:22:24What's happened is the pleasure I get from cream teas
0:22:24 > 0:22:26has activated an area here.
0:22:28 > 0:22:33Because, just like kaymak, it all begins in the amygdala,
0:22:33 > 0:22:35the area in our brain which is the core
0:22:35 > 0:22:39of our emotional response to food.
0:22:39 > 0:22:42It, in turn, triggers something called the reward pathway,
0:22:42 > 0:22:47part of which is the nucleus acumbens.
0:22:47 > 0:22:49This is where desire forms.
0:22:49 > 0:22:51I like it, I want it, I want more of it.
0:22:54 > 0:22:57The desire centre creates the motivation to eat again
0:22:57 > 0:23:01by activating two other parts of the reward pathway.
0:23:02 > 0:23:05This area here is where memories are laid down.
0:23:05 > 0:23:07It's called the hippocampus.
0:23:07 > 0:23:09Memories I'm building up from this occasion,
0:23:09 > 0:23:13being here in a nice tea shop on a sunny day in London.
0:23:15 > 0:23:19My brain is creating a strong memory of the pleasure of eating
0:23:19 > 0:23:23a cream tea so I'll remember it in future and want it again.
0:23:25 > 0:23:27This area of the brain is different,
0:23:27 > 0:23:29it's more complex. It's the frontal lobe.
0:23:29 > 0:23:34This area controls our behaviours and planning.
0:23:35 > 0:23:38When the desire centre signals to this region,
0:23:38 > 0:23:40it's reinforcing the sequence of behaviours...
0:23:42 > 0:23:46..the exact procedure required to get hold of a cream tea.
0:23:48 > 0:23:50Should you see any one of these things again,
0:23:50 > 0:23:54you'll be reminded of how much you enjoy cream teas
0:23:54 > 0:24:00and you'll know exactly what you need to do to get it.
0:24:00 > 0:24:03It's your brain's way of motivating you,
0:24:03 > 0:24:06ensuring that the pleasures you experience in the present
0:24:06 > 0:24:08are repeated in the future.
0:24:10 > 0:24:15Of course, many foods have an impact on the reward pathway.
0:24:15 > 0:24:19But new research is revealing how one drink in particular can actually
0:24:19 > 0:24:22magnify its powerful effect.
0:24:28 > 0:24:29That drink is coffee.
0:24:30 > 0:24:34Here in the UK, we get through 55 million cups each day.
0:24:42 > 0:24:46Part of the appeal is coffee's active ingredient, caffeine.
0:24:47 > 0:24:51And scientists are now close to understanding how caffeine boosts
0:24:51 > 0:24:57our reward pathway by studying, not humans but, surprisingly, bees.
0:25:01 > 0:25:03Alongside chocolate,
0:25:03 > 0:25:05Peru is also a major producer of coffee
0:25:05 > 0:25:09and I've come to see how this beautiful plant reproduces.
0:25:11 > 0:25:14In the wild the plant relies on insects for its pollination
0:25:14 > 0:25:17but therein lies a mystery.
0:25:17 > 0:25:19It seduces pollinating insects,
0:25:19 > 0:25:23looking for food, with the promise of nectar from flowers.
0:25:24 > 0:25:28But it also needs to defend itself from pests, so its cells secrete
0:25:28 > 0:25:30chemicals to keep other insects at bay.
0:25:32 > 0:25:35Plants can't run away and hide from their predators,
0:25:35 > 0:25:39so what they've done is developed a totally different
0:25:39 > 0:25:42evolutionary strategy - chemical weapons.
0:25:42 > 0:25:45So in the case of coffee, for example,
0:25:45 > 0:25:51you have these seeds here which are packed full of caffeine,
0:25:51 > 0:25:54which is toxic to insects in large doses.
0:25:54 > 0:25:56It's found in its leaves,
0:25:56 > 0:25:58it's found throughout the plant, but the weird thing is
0:25:58 > 0:26:03it's even found in flowers and the whole function of a flower
0:26:03 > 0:26:07is to attract insects, so it kind of begs the question
0:26:07 > 0:26:09if something else is going on here?
0:26:11 > 0:26:15Even though caffeine is toxic to insects in large doses,
0:26:15 > 0:26:16there must be something else about
0:26:16 > 0:26:19this chemical that insects find tempting.
0:26:21 > 0:26:24Understand this and it might help us understand
0:26:24 > 0:26:26why humans find coffee so tempting.
0:26:30 > 0:26:34Professor Geraldine Wright of Newcastle University is attempting
0:26:34 > 0:26:38to untangle this puzzle, with the help of her bees.
0:26:38 > 0:26:42Bees are one of the highest forms of life on the planet.
0:26:42 > 0:26:45They have evolved fairly sophisticated brains that allows
0:26:45 > 0:26:48them to learn floral traits and associate them with food.
0:26:49 > 0:26:52The bees are delicately harnessed to allow handling.
0:26:53 > 0:26:56They're then fed a sugar solution.
0:26:56 > 0:26:58Some will also be given caffeine
0:26:58 > 0:27:01to see whether this affects their behaviour.
0:27:01 > 0:27:03Coffee flowers produce a lot of scent.
0:27:03 > 0:27:07They have a beautiful floral scent that's like jasmine.
0:27:07 > 0:27:09And so in this experiment,
0:27:09 > 0:27:12we were training bees to learn to associate a floral scent
0:27:12 > 0:27:14with a food that contained caffeine.
0:27:20 > 0:27:23First, each bee is given a puff of the floral scent...
0:27:27 > 0:27:29..immediately followed by a meal of sugar solution.
0:27:34 > 0:27:38Crucially, half the bees are also given caffeine
0:27:38 > 0:27:39and the other half none.
0:27:43 > 0:27:46The test comes 24 hours later.
0:27:48 > 0:27:51This time, the bees only get a puff of scent.
0:27:51 > 0:27:53Will they remember that yesterday,
0:27:53 > 0:27:55the same scent came along with a meal?
0:27:57 > 0:28:00First, Gerry tests the bees that haven't been given caffeine.
0:28:01 > 0:28:05If they remember the association between scent and food,
0:28:05 > 0:28:09they'll lift their mouthparts in anticipation of a rewarding meal.
0:28:12 > 0:28:16Just 20% respond to the scent but the majority do nothing.
0:28:22 > 0:28:26Next, the bees who'd had a caffeine fix with their food are tested.
0:28:30 > 0:28:35Incredibly, 60% of these bees respond to the scent alone.
0:28:36 > 0:28:41Three times as many bees who'd had caffeine remembered the association
0:28:41 > 0:28:45of scent and sugar reward a day later
0:28:45 > 0:28:48as compared to bees who had no caffeine.
0:28:48 > 0:28:51It's a result which helps begin to explain caffeine's power.
0:28:51 > 0:28:56A little dose of caffeine and nectar goes a long way to helping bees
0:28:56 > 0:28:59to learn and remember the scent of flowers.
0:29:00 > 0:29:02Caffeine itself is making the brain
0:29:02 > 0:29:06believe that these signals are more intense.
0:29:06 > 0:29:09Caffeine is amplifying the experience
0:29:09 > 0:29:11the bees have with sugar when
0:29:11 > 0:29:14they're eating and it's making it seem better.
0:29:14 > 0:29:19The results we found regarding bee memory can be translated to people.
0:29:19 > 0:29:24It's very likely that caffeine is affecting human memory in the same
0:29:24 > 0:29:28way, via the same mechanisms, basically by amplifying reward.
0:29:29 > 0:29:33So it begins to suggest that when we drink a coffee,
0:29:33 > 0:29:36that pleasant feeling of the hot liquid is just made even better by
0:29:36 > 0:29:39the caffeine, so we crave it again.
0:29:41 > 0:29:45And if you add sugar or syrup or cream to your coffee,
0:29:45 > 0:29:48then the caffeine will make this pleasure even more intense,
0:29:48 > 0:29:51so you're even more likely to go back for more.
0:29:53 > 0:29:55It could be that this is part of
0:29:55 > 0:29:58what makes our daily cup so addictive.
0:30:00 > 0:30:03Our brains learn to love the ritual of making or buying coffee.
0:30:05 > 0:30:08We're like bees, buzzing around flowers,
0:30:08 > 0:30:11seeking out that extra hit of pleasure each time we enjoy a cup.
0:30:23 > 0:30:26Our relationship with food is complex
0:30:26 > 0:30:31and the powerful human brain is very adaptable.
0:30:31 > 0:30:35That also means we can learn to love some rather unusual foods.
0:30:35 > 0:30:38We can acquire new tastes.
0:30:38 > 0:30:43Food that is delicious for some is revolting to others
0:30:43 > 0:30:46and that often depends on where you are in the world.
0:30:48 > 0:30:50For example, brain.
0:30:52 > 0:30:57Now as well as being a brain, this is also food, and here in Turkey,
0:30:57 > 0:31:00a sheep's brain salad is something of a delicacy.
0:31:00 > 0:31:05Now this brain is very small and that's because it comes from a sheep
0:31:05 > 0:31:08and sheep don't have to make lots of complex decisions.
0:31:08 > 0:31:12I like to think of sheep wandering the fields in the sunshine and
0:31:12 > 0:31:14occasionally they'll stop and have a bit of a nibble.
0:31:14 > 0:31:16When it comes to food,
0:31:16 > 0:31:19the thought process goes something along the lines of,
0:31:19 > 0:31:21"Grass, stop, eat."
0:31:25 > 0:31:29You can guarantee that while our sheep here might have enjoyed its
0:31:29 > 0:31:33meal of grass, it's never tried a cheesecake for pudding
0:31:33 > 0:31:35or a bit of horseradish on the side.
0:31:35 > 0:31:39And that's because its brain has a key difference to ours.
0:31:43 > 0:31:46If I cut this open, you can see that in some ways,
0:31:46 > 0:31:50it looks like a human brain, except that in a human this area here,
0:31:50 > 0:31:53which is called the frontal cortex, would be much, much bigger,
0:31:53 > 0:31:56and that's because it's where we make all our important
0:31:56 > 0:32:00conscious decisions like where am I going to go on holiday,
0:32:00 > 0:32:04do I really need that extra bit of chocolate cake?
0:32:04 > 0:32:08The frontal cortex is in many ways the area of the brain that makes our
0:32:08 > 0:32:11lives so much more rich and complex than that of a sheep.
0:32:15 > 0:32:20It's our enlarged cortex that has led us to experiment with our food,
0:32:20 > 0:32:25inventing numerous delicacies across cultures and cuisines.
0:32:26 > 0:32:29And that's where it gets a little bit tricky.
0:32:29 > 0:32:33I've never eaten a brain before but there's always a first time for
0:32:33 > 0:32:40everything, so some lemon juice, a little bit of olive oil...
0:32:44 > 0:32:46..and here goes.
0:32:54 > 0:32:56Mmm, yum!
0:32:57 > 0:32:59Aw, God.
0:32:59 > 0:33:02Not at all what I expected.
0:33:02 > 0:33:04I was expecting something a little bit
0:33:04 > 0:33:08rubbery and this is actually more like a sort of strange jelly.
0:33:10 > 0:33:13And not a lovely aftertaste.
0:33:15 > 0:33:19I think this is an acquired taste and it's not one I plan to acquire.
0:33:25 > 0:33:29Acquiring taste is something we excel at.
0:33:29 > 0:33:34It seems that our brains are wired to enjoy the novelty in our food
0:33:34 > 0:33:37and that we can learn to overcome disgust.
0:33:37 > 0:33:42Sometimes, in the case of chilli peppers, even pain.
0:33:54 > 0:33:57To investigate the powerful effect that chilli peppers have on the body
0:33:57 > 0:34:02and brain, I've come to the largest market on the planet
0:34:02 > 0:34:05where tonnes of chillies are sold every day.
0:34:09 > 0:34:11I'm in Mexico, where humans first learned
0:34:11 > 0:34:14to farm the chilli plant some 6,000 years ago.
0:34:19 > 0:34:22The spicy flavour in chillies is
0:34:22 > 0:34:25caused by this chemical called capsaicin.
0:34:25 > 0:34:29I say flavour, but it's really like more of a texture,
0:34:29 > 0:34:31almost a feeling and this is where it all is,
0:34:31 > 0:34:34so everyone says it's the seeds that are spicy and that's not true.
0:34:34 > 0:34:36It's this business here,
0:34:36 > 0:34:40this white spongy layer that we call the placenta.
0:34:40 > 0:34:45It's that bit and that's where pretty much all your capsaicin is manufactured.
0:34:45 > 0:34:49These tiny little dots along there.
0:34:49 > 0:34:52Each one of those is a gland that produces capsaicin.
0:34:54 > 0:34:58And all this capsaicin has a very direct effect on a particular part
0:34:58 > 0:35:00of our biology...
0:35:06 > 0:35:09Something known as the TRPV1 receptor.
0:35:12 > 0:35:15TRPV1 receptors are found in the mouth,
0:35:15 > 0:35:18on the tongue and throughout the body.
0:35:18 > 0:35:23Their purpose is to detect the sensation of scalding heat and raise
0:35:23 > 0:35:26an alarm signal in the brain to protect the body from harm.
0:35:32 > 0:35:34Purely by chance,
0:35:34 > 0:35:37the shape of the capsaicin molecule happens to fit onto
0:35:37 > 0:35:41the TRPV1 receptor like a master key in a lock.
0:35:42 > 0:35:45This triggers the receptors to activate,
0:35:45 > 0:35:48and they send a signal to the brain,
0:35:48 > 0:35:51fooling it into thinking that the mouth is on fire.
0:35:55 > 0:35:58Capsaicin has an almost unrivalled ability
0:35:58 > 0:36:00to generate pain in our bodies.
0:36:03 > 0:36:05So how did a potential food source
0:36:05 > 0:36:08end up with this astonishingly powerful irritant?
0:36:10 > 0:36:13To answer the question, I'm going to need the help of a hopefully
0:36:13 > 0:36:16- friendly parrot. - You look scared, James.
0:36:16 > 0:36:20- I am very scared.- Try not to be. You might get a bit closer.
0:36:20 > 0:36:22Whoa!
0:36:22 > 0:36:25No, I don't want to do this!
0:36:25 > 0:36:26I'm going to give it to you there.
0:36:26 > 0:36:28- Jesus.- It's cos you're snatching it away.
0:36:28 > 0:36:31I know, I know. Oh, and he nearly got me.
0:36:33 > 0:36:35OK. There you go.
0:36:35 > 0:36:38Have a look at that. OK.
0:36:38 > 0:36:40What do you think?
0:36:40 > 0:36:43You like that, don't you? Yeah?
0:36:43 > 0:36:47In the wild, it's relatives of these guys, birds,
0:36:47 > 0:36:50that are the key way that chilli plants disburse their seeds
0:36:50 > 0:36:52everywhere and that's because birds
0:36:52 > 0:36:55are completely immune to the effect of capsaicin.
0:36:55 > 0:36:57It's like it doesn't even exist for them.
0:36:57 > 0:36:59Birds do have a TRPV1 receptor,
0:36:59 > 0:37:02but is a different shape, so no lock and key fit,
0:37:02 > 0:37:05no activation and no feeling whatsoever.
0:37:07 > 0:37:10So the chillies get their seeds spread on the wing
0:37:10 > 0:37:12whilst being left alone by other animals.
0:37:15 > 0:37:18But then came along an ape with a giant frontal cortex
0:37:18 > 0:37:20that learned to love the burn.
0:37:27 > 0:37:31Michael and I have come to a food and music festival here in Bristol...
0:37:33 > 0:37:36..where we're going to compete in a chilli-eating contest.
0:37:40 > 0:37:42We're taking on ten other brave souls...
0:37:45 > 0:37:49..including a man dressed as a chilli and another dressed as a zombie...
0:37:49 > 0:37:52- COMMENTATOR:- Good afternoon, Bristol!
0:37:52 > 0:37:55..to experience first-hand the effect that chillies have on our
0:37:55 > 0:37:57bodies and our brains.
0:37:57 > 0:38:00Welcome to our cathedral of pain and chaos.
0:38:00 > 0:38:03I'm actually feeling slightly nervous.
0:38:03 > 0:38:07I do quite like hot things and although this is not really
0:38:07 > 0:38:11a competition, it is. I'd quite like to do better than you.
0:38:11 > 0:38:14I grew up eating chillies. I've been using them since I was
0:38:14 > 0:38:16eight years old, but famous last words.
0:38:16 > 0:38:18OK, there's a good chance you'll beat me, then.
0:38:18 > 0:38:24Bristol, please give a big round of applause to all the chilli contestants.
0:38:24 > 0:38:25CHEERING AND APPLAUSE
0:38:25 > 0:38:28The things we do in the name of science.
0:38:28 > 0:38:29Good to go. Good luck.
0:38:29 > 0:38:33The principle of the competition is simple, at each round,
0:38:33 > 0:38:37the chillies will get hotter and hotter and the person
0:38:37 > 0:38:39who lasts the longest wins.
0:38:39 > 0:38:43Some very brave, stupid people.
0:38:46 > 0:38:48This is the first chilli that they're going to get.
0:38:48 > 0:38:50It is called a Dutch long chilli.
0:38:53 > 0:38:56On my mark, three, two, one.
0:38:56 > 0:38:58Eat!
0:38:58 > 0:39:03The ferocity of a chilli pepper is measured in Scoville heat units.
0:39:03 > 0:39:06This weighs in at 500 Scoville units.
0:39:06 > 0:39:07The higher the Scoville number,
0:39:07 > 0:39:11the more capsaicin in the chilli and more fiery in that becomes.
0:39:11 > 0:39:14It's got a bit of bite to it.
0:39:14 > 0:39:18There's a long way to go before we encounter the most ferocious chillies
0:39:18 > 0:39:22that can reach millions of Scovilles.
0:39:22 > 0:39:23So this is OK.
0:39:25 > 0:39:28On my mark, three, two, one.
0:39:28 > 0:39:31Eat!
0:39:31 > 0:39:33These are chunky.
0:39:33 > 0:39:35These have got a lot of moisture in, actually.
0:39:35 > 0:39:37Savour it and enjoy them.
0:39:39 > 0:39:42Three, two, one, eat!
0:39:44 > 0:39:46That one went up the nose!
0:39:46 > 0:39:47Oh!
0:39:49 > 0:39:51Please give these guys a round of applause.
0:39:54 > 0:39:57We've now consumed a considerable amount of capsaicin.
0:39:57 > 0:40:02And all those capsaicin molecules are attaching themselves to TRPV1
0:40:02 > 0:40:04receptors in our mouths...
0:40:04 > 0:40:05Go on, get it down you.
0:40:05 > 0:40:10..sending signals to our brains, making us think we are literally on fire.
0:40:11 > 0:40:13My eyes are already beginning to water
0:40:13 > 0:40:16and my pulse is shooting up.
0:40:16 > 0:40:19This is the fight or flight response.
0:40:19 > 0:40:22The fight or flight response normally occurs
0:40:22 > 0:40:24when we sense a threat or danger.
0:40:28 > 0:40:31The body responds with a shot of adrenaline.
0:40:32 > 0:40:35The heart beats harder and faster.
0:40:36 > 0:40:38Pupils dilate.
0:40:38 > 0:40:41You breathe deeper.
0:40:41 > 0:40:43And your arteries widen,
0:40:43 > 0:40:47sending a flood of blood to your muscles to get them ready for action.
0:40:47 > 0:40:51It's all accompanied by a rather more positive feeling that might
0:40:51 > 0:40:55hold the key to why some people like this fiery sensation.
0:40:56 > 0:41:00The thing is that when you eat a really, really hot chilli,
0:41:00 > 0:41:06you also get an endorphin response which is one of the most natural
0:41:06 > 0:41:09opiates. Sometimes you get it when you do exercise. But it's supposed
0:41:09 > 0:41:12to be a feel-good hormone. I'm not sure I've got that yet.
0:41:14 > 0:41:17It's part of the chilli's allure.
0:41:17 > 0:41:19Endorphins are powerful painkillers,
0:41:19 > 0:41:24released by own bodies and so should lessen the chilli's sting.
0:41:24 > 0:41:28But they're also thought to induce a pervasive sense of happiness,
0:41:28 > 0:41:31even a rush, which can be addictive.
0:41:31 > 0:41:33Yes! Nicely done.
0:41:35 > 0:41:36Three, two, one.
0:41:36 > 0:41:38Eat!
0:41:40 > 0:41:42How are you doing?
0:41:42 > 0:41:44HE GROANS
0:41:46 > 0:41:51Our fifth chilli is 15,000 Scovilles.
0:41:51 > 0:41:54With our brain's pain centres in overdrive,
0:41:54 > 0:41:56Michael and I need to dig deep to stay in the contest.
0:42:00 > 0:42:01Oh, dear.
0:42:04 > 0:42:06See you!
0:42:08 > 0:42:10I can feel basically
0:42:10 > 0:42:13the tears coming out, the snot is coming out
0:42:13 > 0:42:16and I thought I was going to vomit for a moment there,
0:42:16 > 0:42:19so I thought it's probably a good time to withdraw.
0:42:19 > 0:42:24Ladies and gentlemen, please give Mr Michael Mosley a round of applause.
0:42:24 > 0:42:29The best thing to soothe the burn is not water, but milk.
0:42:29 > 0:42:31It helps neutralise capsaicin
0:42:31 > 0:42:34because it contains something like casein.
0:42:37 > 0:42:41Casein molecules are attracted to oily substances
0:42:41 > 0:42:43like the capsaicin in chillies.
0:42:43 > 0:42:45They surround the capsaicin,
0:42:45 > 0:42:51preventing it from latching on to the TRPV1 receptors in our bodies
0:42:51 > 0:42:53and it just gets washed away.
0:42:53 > 0:42:56So if you ever encounter curry you can't handle,
0:42:56 > 0:42:59don't bother with water, reach for the dairy.
0:42:59 > 0:43:03Three, two, one, eat!
0:43:06 > 0:43:09I'm still in the running, and on to the sixth chilli.
0:43:11 > 0:43:15And this one is 30,000 Scovilles.
0:43:15 > 0:43:1760 times hotter than the first.
0:43:20 > 0:43:23The reason why psychologists think we like eating chillies
0:43:23 > 0:43:27is there's a minor form of sadomasochism,
0:43:27 > 0:43:30a bit like riding a roller-coaster.
0:43:30 > 0:43:32And I can confirm that.
0:43:32 > 0:43:36Driven by the human rush of excitement.
0:43:38 > 0:43:43It's thrill-seeking, feeding our brain's desire for stimulation.
0:43:43 > 0:43:44Honestly.
0:43:44 > 0:43:47Ladies and gentlemen, please give James Wong a round of applause.
0:43:50 > 0:43:53Excellent work.
0:43:53 > 0:43:55Oh, that milk is good.
0:43:55 > 0:43:57I can still taste it.
0:43:57 > 0:44:01We still don't know why people have different tolerances to fiery foods
0:44:01 > 0:44:05but we can speculate that people with thrill-seeking personalities
0:44:05 > 0:44:08are more likely to expose themselves to the burn
0:44:08 > 0:44:10and may build up a tolerance to capsaicin.
0:44:12 > 0:44:16Out of 12 people, we finished 11th and 12th.
0:44:16 > 0:44:19And the rest are soon dropping like flies.
0:44:19 > 0:44:23Right, so next up, we have Thai red chillies.
0:44:23 > 0:44:26Three, two, one, eat!
0:44:26 > 0:44:31Oh, my goodness me.
0:44:31 > 0:44:33These are naughty.
0:44:33 > 0:44:35Jerry's gone.
0:44:37 > 0:44:41The last two contestants have overcome intense pain
0:44:41 > 0:44:44to reach the penultimate round.
0:44:49 > 0:44:52They now face the infamous Jay's Red Ghost Chilli,
0:44:52 > 0:44:57at a staggering 1.2 million Scovilles.
0:45:00 > 0:45:04Too much for Steve. Drinking milk puts him out of the competition.
0:45:04 > 0:45:06Rebecca has won.
0:45:24 > 0:45:29Our love of chillies shows an experimental side to our eating habits.
0:45:29 > 0:45:32Rewarded by endorphins and a rush of pleasure,
0:45:32 > 0:45:35we've become culinary adventurers,
0:45:35 > 0:45:38constantly seeking out novel food experiences.
0:45:42 > 0:45:45It's even led us to consume a chemical that,
0:45:45 > 0:45:48in its pure form, is frankly poisonous.
0:45:48 > 0:45:52It comes in many guises.
0:45:52 > 0:45:56It can pass right through the barrier which is supposed to protect
0:45:56 > 0:45:59our brains and directly interfere with them.
0:45:59 > 0:46:01It is, of course, alcohol.
0:46:04 > 0:46:07This is red wine.
0:46:07 > 0:46:10It smells rather nice, and I'm sure it's the product of years of hard
0:46:10 > 0:46:13work and experience, but I'm not going to drink it.
0:46:13 > 0:46:16I'm going to send it off to be evaporated.
0:46:20 > 0:46:23Alcohol has a lower boiling point than water.
0:46:23 > 0:46:27So, gently heating the wine in a rotary evaporator turns it into
0:46:27 > 0:46:31a vapour, which rises and can be collected.
0:46:31 > 0:46:34Alcohol is packed with energy.
0:46:34 > 0:46:37Here it is.
0:46:37 > 0:46:39Back again, smelling completely different.
0:46:39 > 0:46:44And by now, it should be almost pure alcohol.
0:46:44 > 0:46:49And if we dim the lights down, we should be able to see it burn.
0:46:52 > 0:46:55Every gram releases seven calories of energy,
0:46:55 > 0:46:58so drinking adds calories to your diet.
0:47:00 > 0:47:03But energy is not why most of us drink.
0:47:06 > 0:47:10Alcohol's popularity arises from what it does to our brains...
0:47:12 > 0:47:16..which means pretty well every culture has invented its own tipple.
0:47:26 > 0:47:29To show just how widely alcohol is enjoyed,
0:47:29 > 0:47:33I've come to somewhere where they produce an extraordinary brew.
0:47:36 > 0:47:41It's in northern Peru, and here the locals have improvised a unique way
0:47:41 > 0:47:44to produce their own steady stream of alcohol.
0:47:48 > 0:47:50These are the Chanka people,
0:47:50 > 0:47:54they have been here as a group for over 700 years and, way back,
0:47:54 > 0:47:56had the Inca for an enemy.
0:47:58 > 0:48:02And throughout their history, they've made a drink called masato.
0:48:02 > 0:48:07Like all cultures they use what's to hand, and for them
0:48:07 > 0:48:09that's the root of the yucca plant.
0:48:09 > 0:48:11Hi there.
0:48:11 > 0:48:12Hello.
0:48:12 > 0:48:14THEY TALK IN OWN LANGUAGE
0:48:14 > 0:48:16Hi there.
0:48:16 > 0:48:20I've joined them to reveal the lengths to which people will go to
0:48:20 > 0:48:22in search of their own tipple.
0:48:23 > 0:48:25Once the yucca roots are peeled,
0:48:25 > 0:48:28they are boiled to soften them and then they are crushed.
0:48:28 > 0:48:31THEY LAUGH
0:48:31 > 0:48:34They are having a good laugh, I'm not entirely sure what it's about.
0:48:34 > 0:48:37All yours. I'm hoping I'll be better at the next bit...
0:48:39 > 0:48:42..when they add a crucial ingredient...
0:48:44 > 0:48:46..spit.
0:48:48 > 0:48:50More.
0:48:50 > 0:48:51More!
0:48:55 > 0:48:56THEY LAUGH
0:48:58 > 0:49:00Yes, that's how it's done.
0:49:05 > 0:49:08Apparently, this is normally just a female only activity.
0:49:08 > 0:49:10I'm not sure
0:49:10 > 0:49:14adding a bit of sort of Gringo male spit to it is adding to the flavour.
0:49:15 > 0:49:19This may look absolutely disgusting but it's actually part of the process
0:49:19 > 0:49:24because the saliva is actually an intrinsic part of the whole thing.
0:49:24 > 0:49:26What happens is the saliva
0:49:26 > 0:49:28in your mouth contains an enzyme called amylase
0:49:28 > 0:49:30and this stuff is all starch.
0:49:30 > 0:49:33What the amylase does is it breaks down the starch and releases
0:49:33 > 0:49:35the sugars inside it.
0:49:35 > 0:49:38If you've ever stuck a cracker in your mouth and left it there
0:49:38 > 0:49:41or perhaps you've stuck some white bread in your mouth and left it
0:49:41 > 0:49:43there, what you'll notice over a little while is
0:49:43 > 0:49:45it starts to taste rather sweet,
0:49:45 > 0:49:48and that's because the amylase in your mouth is breaking down starches
0:49:48 > 0:49:51and releasing sugar. So you have to
0:49:51 > 0:49:55stick it in, run it round, amylase springs into action.
0:49:55 > 0:49:57And then,
0:49:57 > 0:49:59you gob it out.
0:50:03 > 0:50:04The point is to get some sugar.
0:50:07 > 0:50:08Once you have sugar,
0:50:08 > 0:50:12all you need to turn it into alcohol is a little fresh air.
0:50:15 > 0:50:18That's because our atmosphere contains many forms of tiny
0:50:18 > 0:50:21single-celled microorganisms called yeast.
0:50:24 > 0:50:28When one of these yeast cells lands on the chewed yucca,
0:50:28 > 0:50:31it starts to feed on the sugar and begins to multiply.
0:50:38 > 0:50:42And they get the energy to do this from the breakdown of sugar.
0:50:44 > 0:50:47The yeast starts digesting the sugars in the yucca.
0:50:47 > 0:50:51In the process, each sugar molecule is converted into four smaller
0:50:51 > 0:50:57molecules, two of carbon dioxide and two of alcohol, as waste.
0:51:02 > 0:51:05The small size of the alcohol molecule
0:51:05 > 0:51:07is crucial to our enjoyment.
0:51:07 > 0:51:11Being small helps it pass through the barrier around the brain's blood
0:51:11 > 0:51:14vessels and go straight into the brain itself.
0:51:15 > 0:51:19Now, fermentation is at the heart of lots of the things we love.
0:51:19 > 0:51:23Not just booze, but chocolate, yoghurt, and of course, bread.
0:51:23 > 0:51:27Now, with bread, the product of fermentation that you really want is
0:51:27 > 0:51:30not the alcohol but the carbon dioxide.
0:51:30 > 0:51:32Because that's what makes it rise
0:51:32 > 0:51:35and produces that lovely spongy texture.
0:51:35 > 0:51:38There is a small amount of alcohol in the dough, but that gets
0:51:38 > 0:51:42evaporated off when the bread is baked.
0:51:43 > 0:51:48Yet in masato, it's all about the alcohol and it's beginning to build.
0:51:51 > 0:51:54But there's a limit to how strong it can become.
0:51:56 > 0:51:59Once the alcohol level increases to around 6%,
0:51:59 > 0:52:04it becomes concentrated enough to poison many types of yeast, which die.
0:52:04 > 0:52:08And that in turn slows the fermentation process.
0:52:10 > 0:52:14And it's at this point it's ready to enjoy.
0:52:19 > 0:52:22It's my last night and the villagers have invited me to eat with them.
0:52:25 > 0:52:27So, with some trepidation,
0:52:27 > 0:52:31I'm going to sample their unique form of yucca beer.
0:52:41 > 0:52:44Right, OK.
0:52:44 > 0:52:47So, moment of truth. I'm a little apprehensive.
0:52:51 > 0:52:54Hm. It wasn't what I was expecting.
0:52:54 > 0:52:57It's kind of got a bit of an alcoholic kick to it,
0:52:57 > 0:53:00and it's quite bitter.
0:53:00 > 0:53:01It's almost sort of yoghurty.
0:53:08 > 0:53:11THEY SPEAK IN SPANISH
0:53:12 > 0:53:15OK. You drink it pretty well every day, do you?
0:53:15 > 0:53:16Todos los dias.
0:53:16 > 0:53:22Muchas gracias. En ingles, decimos, "cheers".
0:53:22 > 0:53:23Cheers? Cheers.
0:53:23 > 0:53:25- Salud?- "Salud", exactly.
0:53:29 > 0:53:30It's not terribly alcoholic.
0:53:30 > 0:53:34I'd guess it's probably about 4% or 5%.
0:53:34 > 0:53:37But I suspect if you drink enough of it, you get fairly jolly.
0:53:51 > 0:53:56After a few bowls, I'm starting to feel the effects.
0:53:56 > 0:53:58When it gets into your bloodstream,
0:53:58 > 0:54:03it hits your brain and there it really starts to do the business
0:54:03 > 0:54:06because one of the things it does is it affects
0:54:06 > 0:54:09a neurotransmitter called GABA and it actually...
0:54:09 > 0:54:11I'm sorry, I'm slightly losing...
0:54:11 > 0:54:14I'm losing the thread here.
0:54:18 > 0:54:22What I'm trying to say is that GABA is a neurotransmitter or
0:54:22 > 0:54:25chemical messenger that is present throughout the brain.
0:54:28 > 0:54:30Normally, it regulates the brain's activity.
0:54:30 > 0:54:34It's function is to act rather like a brake on brain cells,
0:54:34 > 0:54:38stopping them firing at the wrong time.
0:54:39 > 0:54:42You've got the GABA neurotransmitters
0:54:42 > 0:54:44and what happens is the alcohol...
0:54:46 > 0:54:49Alcohol interferes with the GABA system...
0:54:51 > 0:54:56..by making brain cells more receptive to GABA.
0:54:56 > 0:55:00The potency of GABA increases and so does the dampening effect
0:55:00 > 0:55:03on the brain, switching off areas one by one.
0:55:06 > 0:55:11At first, this can make you feel liberated, excited, amusing,
0:55:11 > 0:55:14because the alcohol starts by switching off
0:55:14 > 0:55:16the areas that control our inhibitions.
0:55:16 > 0:55:19Yep. Life and soul.
0:55:19 > 0:55:24These regions have brain cells with the greatest number of GABA receptors,
0:55:24 > 0:55:27so they are most sensitive to the effects of alcohol.
0:55:27 > 0:55:32The emotional regions of the brain are the next to be suppressed.
0:55:32 > 0:55:35They have almost as many GABA receptors.
0:55:35 > 0:55:40They are followed by your motor controlled region, and then memory.
0:55:40 > 0:55:43What GABA does normally is it switches off parts of your brain,
0:55:43 > 0:55:46I think it's that, but I've slightly forgotten...
0:55:46 > 0:55:48Finally, if you are blind drunk,
0:55:48 > 0:55:50you are left with only
0:55:50 > 0:55:53the most basic parts of your brain still operating.
0:55:53 > 0:55:57They have the least GABA receptors and fortunately,
0:55:57 > 0:56:01they go on keeping you breathing and your heartbeat ticking over,
0:56:01 > 0:56:03even when you're unconscious.
0:56:03 > 0:56:07Thankfully, I am not at that stage tonight.
0:56:09 > 0:56:12Alcohol has a dramatic and in many ways
0:56:12 > 0:56:15a very addictive effect on our brains.
0:56:17 > 0:56:21It is so addictive and pleasurable that humans will find just about
0:56:21 > 0:56:23any way they can to make it,
0:56:23 > 0:56:27even if all you have to start with is some yucca.
0:56:30 > 0:56:33THEY SING
0:56:35 > 0:56:38'The deep connection between our food and brain...'
0:56:38 > 0:56:40Whoa!
0:56:40 > 0:56:41'..is there for a reason...'
0:56:41 > 0:56:43That's intense.
0:56:43 > 0:56:46'It's part of our evolutionary story.'
0:56:49 > 0:56:51We indulge our senses,
0:56:51 > 0:56:54which, in turn, reward us with feelings of pleasure in our minds...
0:56:58 > 0:57:01..keeping us coming back to the table for more.
0:57:08 > 0:57:09Meanwhile, across the world,
0:57:09 > 0:57:13food scientists will continue to delve into the chemistry,
0:57:13 > 0:57:19physics and biology of our food, to try and understand how it works
0:57:19 > 0:57:21on our bodies and on our minds.
0:57:21 > 0:57:26And, all the while, our love affair with food continues to evolve.
0:57:26 > 0:57:30And that's because we are constantly pushing the barriers,
0:57:30 > 0:57:33looking for new ways to stimulate
0:57:33 > 0:57:36our incredibly demanding human brains.
0:57:40 > 0:57:44How does science change your view about what we eat?
0:57:44 > 0:57:48Test your food instincts and find out more facts about food by going
0:57:48 > 0:57:51to the website on the screen
0:57:51 > 0:57:53and follow the links to the Open University.