NARRATOR: HOW OFTEN DO YOU STOP AND REALLY THINK ABOUT YOUR FOOD?

WHY DOES IT TASTE THE WAY IT DOES?

AND HOW DOES IT AFFECT YOUR BODY... AND YOUR MIND?

IN SEARCH OF ANSWERS, TWO EXPERTS WILL TAKE YOU ON GLOBAL CULINARY ADVENTURE.

MEDICAL DOCTOR MICHAEL MOSLEY.... MICHAEL: WE HUMANS ARE PECULIAR.

WE EAT FOODS NO OTHER ANIMALS WOULD EAT.

NARRATOR: AND BOTANIST JAMES WONG...

ULTIMATELY, OUR BODIES AND EVERYTHING WE ARE COMES FROM OUR PLATES.

NARRATOR: WILL DISCOVER THE HIDDEN SCIENCE IN EVERY MOUTHFUL.

MICHAEL: LOOK AT ALL THIS LOVELY FAT AND SUGAR.

YUMMY.

NARRATOR: THIS TIME, THEY'RE ON A MISSION TO REVEAL THE MYSTERIES OF TASTE.

WONG: THE AROMA COMPOUNDS WAFT UP THE BACK OF YOUR NOSE.

NARRATOR: WHY SOME TASTES ARE PURE JOY...

WHILE OTHERS REVOLT.

AND THEY'LL DISCOVER HOW OUR SENSE OF TASTE AND SMELL HAS EVOLVED.

SO WE NOT ONLY ENJOY OUR FOOD BUT ARE PROTECTED FROM TASTES THAT COULD HARM US.

MICHAEL: THIS IS DELICIOUS SCIENCE.

[BELL TOLLING] NARRATOR: FLAVOR MAKES OUR FOOD DELICIOUS.

EACH FLAVOR IS A POTENT COMBINATION OF AROMA AND TASTE MOLECULES.

GET THAT COMBINATION RIGHT, AND FOOD TASTES HEAVENLY.

BUT WHAT IS TASTE?

TO EXPLORE THAT, MICHAEL'S GOING TO TAKE A LOOK AT THAI CUISINE.

THAI FOOD IS PARTICULARLY GOOD AT EXCITING OUR FULL RANGE OF TASTE RECEPTORS.

AND ALL ON ONE PLATE.

MICHAEL: SO, THIS IS A THAI STIR-FRY, AND I'M VERY FOND OF THAI.

THERE IS A...A BIT OF FRIED CHICKEN, LEMON, GARLIC, ONION-- A REAL SORT OF EXPLOSION OF TASTE.

AND IT'S REALLY STRANGE TO THINK THAT ALL OF THESE SENSATIONS WHICH ARE GOING ON IN MY MOUTH AT THE MOMENT ARE GENERATED BY 5 SIMPLE TASTES.

NARRATOR: IN FRONT OF MICHAEL ARE 5 LIQUIDS CONTAINING CHEMICALS THAT WILL TRIGGER EACH DIFFERENT TASTE.

HE HAS NO IDEA WHICH IS WHICH.

MICHAEL: SALTY, THAT'S DEFINITELY SALTY.

SWEET.

THAT IS SORT OF BITTER, A BIT LIKE COFFEE.

AND THIS...IS SIMILAR BUT MORE LEMONY AND MAKES YOUR MOUTH PUCKER UP.

THIS IS SOUR.

AND THIS ONE IS REALLY HARD TO DESCRIBE.

THIS IS THE TASTE THAT HAS BEEN MOST RECENTLY DISCOVERED.

THIS IS UMAMI.

NARRATOR: THE WORD UMAMI IS A DERIVATION OF THE JAPANESE WORD FOR A "PLEASANT, SAVORY TASTE."

AND IT IS VERY, VERY STRANGE TO THINK THAT EVERY TASTE SENSATION YOU EVER HAVE WILL CONSIST OF ONE OR MORE OF THESE TASTES.

NARRATOR: THE SENSATIONS HAPPEN HERE... ON THE SURFACE OF THE TONGUE.

THE TONGUE HOLDS AROUND 4,000 TASTE BUDS.

INSIDE THEM ARE THE 5 TASTE RECEPTORS.

IN HUMANS, THIS IS WHERE TASTE BEGINS.

EVOLUTION UNDERPINS OUR RELATIONSHIP WITH FOOD.

BUT WHY THESE 5 TASTES?

WHAT IS THEIR PURPOSE?

TO FIND OUT, MICHAEL IS GOING TO START BY LOOKING AT THE TASTE THAT'S MOST RECENTLY BEEN DISCOVERED.

HE'S TRAVELED HERE TO BUÑOL, SPAIN, TO PARTICIPATE IN AN EXTRAORDINARY CELEBRATION OF THE WORLD'S MOST POPULAR FRUIT, WHICH IS RICH IN UMAMI.

I'M HERE IN SOUTHERN SPAIN WITH ABOUT 20,000 OTHER PEOPLE TO CELEBRATE THE TOMATO.

[MUSIC PLAYING, SINGING] WELCOME TO LA TOMATINA AND THE WORLD'S BIGGEST FOOD FIGHT.

NARRATOR: IT'S BEEN RUNNING FOR OVER 70 YEARS, AND IT'S THOUGHT IT STARTED WITH A STREET FIGHT THAT WAS SO MUCH FUN THE LOCALS DECIDED TO DO IT AGAIN THE NEXT YEAR AND THE NEXT.

AS WELL AS MAKING A PERFECT FOOD MISSILE, TOMATOES CARRY A HEAVY PUNCH OF UMAMI.

THE TROUBLE WITH BEING AT THE BACK IS YOU GET HIT A LOT.

NARRATOR: BUT WHAT EXACTLY IS UMAMI?

AND WHY DOES IT HAVE SUCH A POWERFUL HOLD OVER US?

THE ANSWER IS INSIDE THE TOMATOES.

TO GET AT THE UMAMI, MICHAEL IS GOING TO BLEND THEM, THEN SPIN THEM AT HIGH SPEED IN A CENTRIFUGE, FILTER, THEN FINALLY STIR AND SIMMER TO CONCENTRATE THE TASTE.

MICHAEL: AFTER ALL THAT BOILING DOWN, THIS IS ALL THAT'S LEFT.

[SNIFFS] AND IT NO LONGER SMELLS TOMATOEY AT ALL, BECAUSE THOSE VOLATILE FLAVORS HAVE BEEN BOILED OFF, AND THIS STUFF...

DOESN'T TASTE TOMATOEY EITHER.

IT TASTES SALTY, EARTHY, MEATY.

NARRATOR: WHAT MICHAEL'S TONGUE IS SENSING IS A CHEMICAL KNOWN AS GLUTAMATE.

IT'S AN AMINO ACID, A TYPE OF MOLECULE DERIVED FROM THE PROTEIN IN THE TOMATO.

WHENEVER YOU GET GLUTAMATE IN FOOD, IT TRIGGERS THAT UMAMI TASTE.

AND IT'S A FLAVOR WE ENJOY SO MUCH, IT ACTUALLY FUELS A DESIRE FOR MORE UMAMI-RICH FOOD.

IT'S OUR LOVE OF THE GLUTAMATE IN TOMATOES THAT HAS MADE THEM SUCH AN IMPORTANT CROP FOR THIS REGION.

[BELL TOLLING] NARRATOR: IT'S FOUND HERE IN THE ANCIENT OAK FORESTS OF SOUTHWEST SPAIN, HOME OF THE CHUNKY LOCAL PIG KNOWN AS THE PATA NEGRA.

THE PIGS ROAM FREELY, FORAGING FOR WHATEVER THEY CAN FIND.

BUT THEIR FAVORITE TREATS ARE THE ACORNS THAT FALL FROM THE OAKS EVERY WINTER.

AND IT TURNS OUT THAT PIGS AND ACORNS ARE A MATCH MADE IN HEAVEN.

TOGETHER THEY MAKE THE MOST DELICIOUS AND MOST EXPENSIVE UMAMI-PACKED HAM IN THE WORLD... IBERICO HAM.

[CHICKEN CLUCKS] IT'S EARLY MORNING IN JANUARY.

[DOG BARKING] ACORN SEASON IS COMING TO AN END, AND THE MARQUEZ FAMILY IS PREPARING FOR ONE OF THEIR MOST IMPORTANT EVENTS OF THE YEAR.

IN THIS PART OF SPAIN, THE ANNUAL KILLING OF A PIG IS A MAJOR EVENT.

IT'S KNOWN AS A MATANZA, AND IT INVOLVES THE GATHERING OF AN ENTIRE FAMILY.

[SPEAKING SPANISH] NARRATOR: THIS ANCIENT, RURAL TRADITION DATES BACK TO A TIME WHEN THE PIG WOULD BE EXPECTED TO PROVIDE SUSTENANCE FOR THE FAMILY FOR MONTHS.

THE PROCESS INVOLVES NOT JUST THE SLAUGHTER OF A PIG, BUT ALSO THE PREPARATION AND SEASONING OF THE MEAT.

AFTER THE SLAUGHTER, IT WILL TAKE THE FAMILY THE ENTIRE DAY TO TURN OVER 300 POUNDS OF PIG INTO ENOUGH MEAT TO KEEP THEM GOING ALL YEAR.

MAN: [SPEAKING SPANISH] TRANSLATOR: THIS HAM WILL BE THE BEST BECAUSE OF THE FAT.

NARRATOR: THE SECRET TO THE INTENSE UMAMI TASTE BEGINS WITH THE EXTRAORDINARILY THICK LAYER OF FAT, WHICH COMES FROM THE ACORNS THE PIG ENJOYED IN LIFE.

THE ACORN FAT IS RICH IN OLEIC ACID, THE SAME FATTY ACID THAT IS FOUND IN OLIVES.

THE PATA NEGRA PIG IS ABLE TO EAT AN INCREDIBLE 22 POUNDS OF ACORNS EVERY DAY, MEANING THEIR BODIES BECOME SATURATED IN THE OLEIC ACID FROM THE ACORNS.

NOTHING OF THE PIG WILL GO TO WASTE, BUT IT IS THE HIND LEGS THAT WILL BE TRANSFORMED INTO THE UMAMI RICH HAM.

MOST HAMS END UP HERE, IN THE DARKNESS OF AN IBERIAN CELLAR.

THIS IS WHERE BIOCHEMISTRY KICKS IN, AND THE EXQUISITE UMAMI TASTE FORMS.

THE SURFACE OF THE HAMS ARE UNDER CONSTANT ATTACK.

MICROBES AND OXYGEN IN THE AIR REACT WITH THE FAT ON THE OUTSIDE, MAKING IT YELLOW AND RANCID.

BUT THE MEAT WITHIN IS PROTECTED.

THE ACORN FED FAT LAYER IS SO THICK, IT CAN KEEP THE MEAT AIR-FREE FOR UP TO 3 YEARS, MUCH LONGER THAN ANY OTHER HAM.

THIS ALLOWS THE NATURAL CHEMISTRY LOCKED INSIDE THE FLESH TO UNFOLD.

THE MEAT STARTS TO CURE.

OVER THE YEARS, NATURALLY OCCURRING ENZYMES BREAK THE PROTEINS IN THE MEAT DOWN INTO THEIR BASIC BUILDING BLOCKS--AMINO ACIDS.

ONE OF THESE IS THE ALL-IMPORTANT GLUTAMATE, THE MOLECULE RESPONSIBLE FOR THE TASTE OF UMAMI.

THE LONGER MEAT CURES, THE GREATER THE BUILD-UP OF THE GLUTAMATE AND THE STRONGER THE TASTE WILL BECOME.

AND TIME IS EXACTLY WHAT IT'S THICK FATTY CASE PROVIDES EACH HAM.

AFTER UP TO 3 YEARS, THESE HAMS HAVE 50 TIMES THE GLUTAMATE LEVELS OF FRESH MEAT.

MAKING THEM THE WORLD'S FINEST, MEATIEST, MOST DELICIOUS UMAMI-TASTING HAMS.

WOMAN: [SPEAKING SPANISH] TRANSLATOR: THIS IS THE FRUITS OF OUR LABOR.

WE WORK HARD ALL YEAR SO WE CAN EAT WELL ALL YEAR.

NARRATOR: IT'S A TASTE PRIZED BY CHARCUTERIE CONNOISSEURS THE WORLD OVER.

BUT THERE'S A BIOLOGICAL REASON WHY WE ARE DRAWN TO THE UMAMI FLAVOR OF GLUTAMATE.

SO THE REASON--MMM-- WHY THIS HAM IS SO DELICIOUS IS BECAUSE GLUTAMATE IS ONE OF THE BUILDING BLOCKS OF PROTEIN.

NARRATOR: AND PROTEIN IS ESSENTIAL TO THE BUILDING AND RUNNING OF EVERY CELL IN OUR BODIES.

SO, WHAT THIS HAM IS REALLY SAYING TO ME...IS EAT ME BECAUSE I WILL MAKE YOU BIG AND STRONG.

AND THE WAY IT SENDS THAT MESSAGE IS, OF COURSE, VIA MY TASTE BUDS.

NARRATOR: AS FOOD ENTERS THE MOUTH, IT MEETS THE TONGUE, A SEETHING LANDSCAPE OF MUSCLE COVERED BY SPIKY PAPILLAE.

THESE HELP MOVE EACH MOUTHFUL OF FOOD AROUND.

AS IT SWIRLS ACROSS THE TONGUE, THE FOOD COMES ACROSS LARGER, DOME SHAPED PAPILLAE, AND HERE WE FIND THE TASTE BUDS.

THE GLUTAMATE ENTERS EACH BUD, WHERE IT ENCOUNTERS THE 5 TASTE RECEPTORS, BUT THE GLUTAMATE MOLECULE HAS A DISTINCTIVE SHAPE THAT CAN ONLY ACTIVATE THE UMAMI RECEPTOR.

SENDING A SIGNAL TO THE BRAIN THAT TELLS US, MMM, THAT MOUTHFUL OF FOOD IS ABSOLUTELY DELICIOUS.

WE'RE HARDWIRED TO ENJOY THE TASTE OF UMAMI BECAUSE IT SIGNALS THE PROTEIN WE NEED TO BUILD OUR BODIES, BUT WE CAN'T SURVIVE ON PROTEIN ALONE.

WE WOULD GRIND TO A HALT WITHOUT A READY SUPPLY OF ENERGY, SO, JAMES IS INVESTIGATING ANOTHER TASTE RECEPTOR THAT FIRES OFF WHENEVER IT ENCOUNTERS THE CHEMICALS THAT GIVE US A QUICK ENERGY HIT.

JAMES: YUM.

WHEN YOU BITE INTO A STRAWBERRY, IF YOU HAD TO PICK ONE WORD TO DESCRIBE ITS TASTE, YOU'D PROBABLY PICK SWEET, AND THAT'S HOW OUR BODIES DETECT THE AMOUNT OF SUGAR THAT'S IN FRUIT.

NARRATOR: BUT SUGAR IN NATURE SELDOM COMES ON ITS OWN.

IT'S USUALLY BALANCED BY ANOTHER TASTE, THE TASTE OF ACID.

JAMES: I'M GOING TO SHOW YOU THAT WITH A FANTASTICALLY GEEKY PIECE OF KIT HERE.

THIS IS A PH METER, AND IT DETECTS HOW ACID SOLUTIONS ARE.

YOU'VE GOT PURE WATER ON ONE END, WHICH IS 7, AND HYDROCHLORIC ACID AS 1, ABOUT AS ACIDIC AS IT GETS.

NARRATOR: JAMES IS GOING TO TEST A RANGE OF FRUIT... JAMES: GET SOME OF THAT JUICE OUT.

NARRATOR: TO FIND OUT WHERE THEY FIT ON THE SCALE, STARTING WITH A STRAWBERRY.

YEAH, IT'S GOING DOWN.

FOR SOMETHING THAT MOST PEOPLE DESCRIBE AS SWEET, THIS IS PRETTY ACIDIC STUFF.

LOOK AT THAT, 3.5.

RIGHT THERE.

NARRATOR: WATERMELON IS LESS ACIDIC AT 5.5.

WHILE ORANGE IS THE SAME AS STRAWBERRY.

JAMES: 3.5 AGAIN.

LAST UP, GRAPEFRUIT.

HUH.

3.5, TOO.

SO THIS IS QUITE ODD.

ALL THIS FRUIT IS THE SAME PH, YET PEOPLE DESCRIBE STRAWBERRIES AS TASTING SWEET, DESPITE HAVING A SIMILAR AMOUNT OF ACID.

NARRATOR: STRAWBERRIES HAVE A CUNNING ABILITY TO HIDE THEIR ACIDITY.

SO WHY PRODUCE IT IN THE FIRST PLACE?

[BIRDS CHIRPING] JAMES HAS COME TO THE STRAWBERRY FIELDS OF KENT, ENGLAND, TO FIND THE ANSWER.

[SNIFFS] JAMES: STRAWBERRY PLANTS HAVE SPECIFICALLY EVOLVED THIS SWEET, SUCCULENT FRUIT HERE TO ENCOURAGE ANIMALS TO EAT THEM.

AND THAT'S BECAUSE WHEN THESE SEEDS PASS THROUGH THE DIGESTIVE TRACT OF AN ANIMAL, THEY'RE DEPOSITED, WITH A BIT OF FERTILIZER, FAR AND WIDE, HELPING THE STRAWBERRY'S EMPIRE GROW.

THE THING IS, THAT ONLY WORKS WHEN THE SEED IS FULLY MATURE AND READY TO SPROUT.

UNTIL THAT POINT THEY'RE NOT SWEET AT ALL.

IN FACT, THEY'RE PACKED FULL OF ACID, MAKING THEM TASTE SOUR.

IT'S AN ANIMAL DETERRENT.

NARRATOR: THE MILD ACIDIC SOLUTION FROM THE UNRIPENED FRUIT WASHES OVER THE TONGUE, STIMULATING THE SOUR RECEPTORS.

THE BRAIN INTERPRETS THIS TASTE AS UNPLEASANT AND A SIGN THAT THE FOOD COULD BE SPOILED OR UNFIT TO EAT.

IT'S A BIOLOGICAL REACTION THAT PLANTS USE TO THEIR OWN ENDS: A TASTE STRONG AND REPELLENT ENOUGH TO PUT MOST ANIMALS OFF.

BUT JUST AT THE RIGHT MOMENT, WHEN THE PLANT'S SEEDS HAVE MATURED, IT NEEDS TO MASK THE ACIDITY TO BE MORE PALATABLE.

ALL THE ACID IS STILL THERE, BUT THE FRUIT BECOMES FLOODED WITH SUGAR, PRODUCED WHEN HORMONES FROM THE SEEDS ANNOUNCE THEY ARE READY TO BE EATEN.

THE SUGARS REACT WITH OTHER PLANT MOLECULES AND MAKE ATTRACTIVE RED PIGMENTS THAT SAY, "EAT ME."

I KNOW YOU'RE NOT SUPPOSED TO EAT THEM UNTIL YOU'VE PAID, BUT... THAT'S THE POINT.

THEY ARE IRRESISTIBLE.

NARRATOR: THE PLANT, HAVING SACRIFICED SOME SUGAR, GETS ITS SEEDS SPREAD.

AND IN RETURN, THE DINER GETS A SUGAR REWARD.

BUT THE STRAWBERRY IS SNEAKY.

BECAUSE WE MAY NOT BE GETTING AS MUCH SWEET SUGAR AS WE THINK.

RIPE STRAWBERRIES TASTE SWEETER THAN BLUEBERRIES, EVEN THOUGH BLUEBERRIES CONTAIN ALMOST TWICE AS MUCH SUGAR.

SO HOW IS THE STRAWBERRY MAKING ITSELF TASTE SO SWEET?

INCREDIBLY, STRAWBERRIES HAVE ALTERED THE WAY THEY TASTE USING THE POWER OF SMELL.

36 AROMA MOLECULES DECEIVE OUR BRAINS INTO THINKING WE'RE TASTING A LOT MORE SUGAR THAN WE ARE.

IMAGINE IF WE COULD REPLICATE THIS CLEVER TRICK IN OTHER FOODS.

THEN WE'D BE ABLE TO PRODUCE SATISFYINGLY SWEET-TASTING TREATS USING A LOT LESS SUGAR.

OUR SENSE OF TASTE IS NOT JUST ABOUT ATTRACTING US TO WHAT'S GOOD TO EAT AND WHEN...

IT'S ALSO EVOLVED WAYS TO HELP US AVOID FOODS THAT CAN KILL US.

TAKE THE SEEDS IN FRUIT.

EVEN A FEW CRUSHED CHERRY OR PLUM SEEDS CAN PRODUCE ENOUGH CYANIDE IN THE GUT TO CAUSE PARALYSIS, LIVER, AND KIDNEY DAMAGE.

RHUBARB LEAVES CONTAIN THE SAME CHEMICAL USED TO MAKE BLEACH.

AND JUST 5 RAW, UNCOOKED KIDNEY BEANS CONTAIN ENOUGH PHYTOHAEMAGGLUTININ TO BRING ON VOMITING, NAUSEA, AND DIARRHEA.

EATING CAN BE A DANGEROUS BUSINESS.

JAMES HAS COME TO PERU WHERE THERE'S AN EVERYDAY FOOD YOU MIGHT NOT EXPECT TO BE A THREAT.

JAMES: THE WORLD IS FULL OF THINGS THAT LOOK LIKE THEY COULD BE INTERESTING TO EAT...

BUT SOME THINGS MIGHT NOT BE SUCH A GOOD IDEA.

TAKE THE POTATO, FOR INSTANCE.

IS IT FRIEND OR FOE?

NAOMI: THE POTATO PLANT ORIGINATED IN SOUTH AMERICA.

BUT MOST OF THESE WILD POTATOES WOULD HAVE BEEN COMPLETELY LEFT ALONE BECAUSE OF THEIR INTENSELY SHARP, BITTER TASTE.

JAMES: POTATOES BELONG TO THE DEADLY NIGHTSHADE FAMILY, WHICH IS PACKED FULL OF SPECIES THAT ARE SUPER, SUPER TOXIC.

IT TASTES INCREDIBLY BITTER.

BAD IDEA TO DO WHAT I'M DOING.

BUT I'M JUST GOING TO...

I BARELY PUNCTURED THIS WITH MY TEETH, AND ALREADY A BITTER BLOOM IS GOING THROUGHOUT MY MOUTH THAT MAKES ME WANT TO SPIT IT OUT INSTANTLY.

THAT'S MY SENSE OF TASTE TELLING ME INSTANTLY, THIS IS NOT GOOD FOR YOU, GET RID OF IT.

NARRATOR: BITTER HAS A CRUCIAL ROLE TO PLAY IN OUR SURVIVAL.

IT'S A WARNING SIGN.

JAMES: YOUR SENSE OF TASTE IS REALLY A COMPLEX CHEMICAL DETECTOR THAT ALLOWS HEALTHY, GOOD-FOR-YOU FOODS IN AND KEEPS TOXICS THINGS OUT.

NARRATOR: THE POTATO USES THIS TO PROTECT ITSELF FROM BEING EATEN.

YOU SEE ALL THIS GREEN BLUSH OVER THE SURFACE?

THAT'S EVIDENCE IT'S STARTED TO GROW AND PRODUCE SOLANINE.

THEY GENERALLY ARE PACKED IN YOUNG GROWING TIPS TO HELP PROTECT THE PLANT EVEN MORE.

SO I'M GOING TO TRY THIS SPROUTED POTATO, AND IT SHOULD BE EVEN WORSE.

GOD, WHY DID I DO THAT?

NARRATOR: BECAUSE THE CONSEQUENCES OF EATING POISON CAN BE SO DEADLY, WE HAVE 25 TYPES OF BITTER RECEPTOR ALL ON THE LOOKOUT FOR TOXINS, 10 TIMES MORE THAN WE HAVE FOR SWEET.

BECAUSE SWEET IS NICE, BUT BITTER CAN BE DEADLY.

I'M GONNA SPIT THIS OUT.

SORRY.

NARRATOR: SO IF THE ORIGINAL POTATOES WERE POISONOUS, HOW DID THEY BECOME SUCH AN IMPORTANT PART OF OUR DIET?

SURPRISINGLY, WE HAVE THE INCA TO THANK.

THIS IS THE SACRED VALLEY OF THE INCA, IN PERU.

JAMES HAS TRAVELED HERE AS THERE ARE MORE VARIETIES OF POTATOES THAN ANYWHERE ELSE ON PLANET.

IN FACT, THEY'VE BEEN GROWING POTATOES HERE FOR THOUSANDS OF YEARS.

AND THIS IS WHERE THE POISONOUS SOLANINE WAS GRADUALLY BRED OUT.

JAMES: YOU KNOW, WHEN PEOPLE TALK ABOUT THE INCA, THEY TEND TO MENTION LOST CITIES AND TEMPLES AND GOLD, BUT ALL OF THIS HAS NOTHING TO DO WITH POWER OR STATUS.

EVERYTHING YOU SEE HERE ONLY EXISTS TO GROW CROPS, AND KING AMONGST THEM, THE POTATO.

NARRATOR: BUT FOR THE QUECHUA PEOPLE WHO LIVE HIGH IN THE ANDES, THE BATTLE TO TAME THE POISONOUS SPUD IS STILL BEING FOUGHT.

THIS IS MARTIN CALISAYA, WHOSE FAMILY LIVE IN THE VILLAGE OF TASTAYOQ, LOCATED 13,000 FEET HIGH IN THE MOUNTAINS.

THEIR LIVES DEPEND ON THE POTATO BECAUSE ALMOST NOTHING ELSE WILL GROW AT THIS ALTITUDE, SO SPUDS PROVIDE VIRTUALLY ALL THEIR NUTRITION, AND THEY GROW A HUGE VARIETY TO SURVIVE IN THIS HARSH ENVIRONMENT.

NARRATOR: BUT EVEN WITH A HUNDRED DIFFERENT VARIETIES, A HARD FROST COULD SPELL DISASTER.

SO AS A PRECAUTION THEY ALSO GROW THE HARDIEST KNOWN POTATO IN THE WORLD, ONE THAT CAN SURVIVE EVEN THE TOUGHEST WINTER.

THE ONLY DOWNSIDE?

THEY'RE BITTER, POISONOUS, AND INEDIBLE, PACKED FULL OF DEADLY SOLANINE.

JAMES: THE INCREDIBLE THING IS THE PEOPLE FROM THE ANDES HAVE DEVELOPED AN INGENIOUS TECHNOLOGY THAT TURNS POISON INTO DINNER.

[SPEAKING FOREIGN LANGUAGE] NARRATOR: THE TRICK IS TO FREEZE-DRY THE POTATOES SO THEY CAN BE STORED FOR YEARS.

JAMES: IN ORDER TO GET MAXIMUM FREEZE FACTOR, THE QUECHUA NEED TO FIND THE VERY THE COLDEST SPOT, AND THAT MEANS GOING RIGHT UP THERE.

NARRATOR: ONCE A YEAR, THE CALISAYA FAMILY HAUL THEIR CROP OF INEDIBLE, BITTER POTATOES TO A SITE THAT'S 1,000 FEET HIGHER THAN THE VILLAGE, READY TO BEGIN A FOOD PROCESSING TECHNIQUE THAT DATES BACK AROUND 2,000 YEARS.

[HORSE NEIGHS] AT 14,000 FEET, THEY REACH THE CORRAL WHERE THE POTATOES WILL BE PROCESSED.

JAMES: GROWING POTATOES THE TRADITIONAL WAY IS INCREDIBLY LABOR INTENSIVE.

BUT HERE, YOU'VE GOT TO HAUL THIS STUFF UP A MOUNTAIN, AND IN THIS THIN AIR, EVEN JUST THE ACT OF SPACING THEM APART SO FROST GETS TO THEM IS KILLING ME.

NARRATOR: AT NIGHT, THE TEMPERATURE PLUMMETS.

ICE CRYSTALS FORM THROUGHOUT THE POTATO, RUPTURING THE CELL WALLS.

THIS ALLOWS THE POISONOUS SOLANINE TO DRAIN OUT.

AFTER A NIGHT OUT IN SUB ZERO TEMPERATURES, THESE GUYS ARE FROZEN SOLID.

NARRATOR: UP TO 80% OF THE DEADLY SOLANINE IS PRODUCED CLOSE TO THE SKIN, AND THE TREADING PROCESS BREAKS THE SKINS ENOUGH TO ALLOW AN ESCAPE ROUTE FOR THE POISON.

DURING THE DAY, WHEN THE SCORCHING SUN IS HIGH IN THE SKY, THE POTATOES BEGIN TO THAW.

WITH THE CELL WALLS RUPTURED AND THE SKINS BROKEN, WATER DRAINS OUT, CARRYING THE DEADLY SOLANINE WITH IT, LEAVING A DRIED, SHRIVELED PRODUCT KNOWN AS CHUNO.

JAMES: THIS IS IT, THIS IS THE END RESULT.

AND OK, THEY MIGHT NOT LOOK IRRESISTIBLE, BUT THIS IS MAGIC.

IN THIS FORM, THEY CAN BE STORED FOR A DECADE AND STILL BE EATEN.

IT IS THE ULTIMATE IN FOOD SECURITY.

NARRATOR: SO EVEN IF THE WINTER DESTROYS THE BULK OF THEIR CROP, MARTIN AND HIS FAMILY WILL BE SURE TO HAVE ENOUGH FOOD.

THE FLAVOR IS GREAT.

IT'S KIND OF FLOWERY LIKE A CHESTNUT, LIKE A ROASTED CHESTNUT BUT WITH A KIND OF SMOKY, OAKY RICHNESS TO IT.

I'VE GOT TO SAY... NARRATOR: THE QUECHUA HAVE LEARNED TO OUTSMART THE INCREDIBLE BITTERNESS OF POISONOUS POTATOES.

THANKS TO THEIR INGENIOUS PROCESS OVER HUNDREDS OF GENERATIONS, NEARLY ALL THE BITTER SOLANINE HAS BEEN BRED OUT OF THE HUMBLE POTATO WE EAT TODAY.

HOW WE EXPERIENCE OUR FOOD IS FAR MORE THAN JUST ENJOYING WHAT WE EAT.

IT'S ACTUALLY A POWERFUL SURVIVAL MECHANISM.

OUR SENSE OF TASTE EVOLVED TO GUIDE US THROUGH A VERY DIFFERENT WORLD TO THE ONE WE LIVE IN NOW.

IT WAS A WORLD WHERE THINGS THAT TASTED SWEET WERE GOOD FOR US BECAUSE THEY GAVE US INSTANT ENERGY AND WHERE THINGS THAT WERE BITTER WERE OFTEN BAD BECAUSE THEY MIGHT BE POISONOUS.

IN THE MODERN WORLD, OF COURSE, IT'S OFTEN THE OTHER WAY AROUND.

THERE'S ANOTHER REALLY IMPORTANT TASTE, WHICH IS ALSO OFTEN CONFUSED BY THE MODERN WORLD.

IT'S A TASTE WHICH IS BOTH AN INVITATION AND A WARNING.

IT IS...SALT.

WE'RE SO USED TO THE TASTE OF SALT THAT WE SOMETIMES FORGET JUST HOW WEIRD IT IS.

LET ME SHOW YOU SOMETHING WHICH IS REALLY QUITE SURPRISING.

I'M GOING TO WHIZ UP SOME COFFEE.

[GRINDING] BIT OF BOILING WATER.

I'VE GOT A FRESH-BREWED COFFEE HERE.

LET'S GIVE IT A GO.

AND THAT IS REALLY QUITE...

BITTER.

[GRINDING] HERE WE GO.

NOW THAT'S QUITE STRANGE BECAUSE IT'S VERY DIFFERENT.

THE BITTERNESS HAS BEEN REMOVED.

IT DOESN'T ACTUALLY MAKE IT PLEASANTER, I HAVE TO SAY.

IT JUST MAKES IT VERY DIFFERENT.

BECAUSE ODDLY WHAT IS HAPPENING IS THAT THE SODIUM IN THE SALT IS BLOCKING THE BITTER RECEPTORS.

AND SO IT REALLY DOESN'T TASTE ANYTHING LIKE AS BITTER AS IT DID, WHICH FOR ME IS SHAME BECAUSE I ACTUALLY LIKE BITTER COFFEE.

BUT IF YOU DON'T, THAN THIS IS A VERY NEAT TRICK.

NARRATOR: AND IT'S THIS ABILITY TO MAKE FOOD MORE PALATABLE, MORE DELICIOUS... THAT GIVES SALT SUCH A POWERFUL HOLD OVER US, AND WE'VE EVOLVED A LIKING FOR SALT, BECAUSE IT'S ESSENTIAL TO LIFE.

BILLIONS OF YEARS AGO, LIFE EVOLVED IN THE OCEANS.

EXACTLY HOW IT BEGAN NO ONE KNOWS.

BUT AS THE FIRST SIMPLE CELLS TOOK SHAPE, THEY ENTRAPPED A LITTLE BIT OF THE SALTY WATER INSIDE THEMSELVES.

TODAY EVERY CELL IN OUR BODIES STILL CARRIES A LITTLE SALTY WATER, A DISTANT ECHO OF OUR ANCIENT ORIGINS IN THE SEA.

JAMES: SEAWATER MIGHT TASTE TERRIBLE, BUT THE TASTE OF A LITTLE BIT OF SALT HAS THIS UNIVERSAL APPEAL.

WE LIKE IT BECAUSE WE NEED IT.

SALT IS VITAL FOR LIFE.

JAMES IS IN BRITTANY, FRANCE, WHERE THEY HAVE BEEN COAXING SALT OUT OF THE OCEAN FOR THOUSANDS OF YEARS.

THIS LANDSCAPE HAS BEEN UTTERLY TRANSFORMED OVER TIME... AS NATURAL SALT MARSHES HAVE BEEN PAINSTAKINGLY SCULPTED INTO A VAST NETWORK OF EVAPORATION PONDS.

SOPHIE BONNET-QUESTIAU IS ONE OF 250 SALT FARMERS TENDING TO THEIR OWN NETWORK OF PONDS, EACH CALLED A SALINA.

SOPHIE: IT'S THE TRADITIONAL WAY BECAUSE IT HAS STARTED IN THE NINTH CENTURY.

THE TECHNIQUE IS REALLY THE SAME.

NARRATOR: WHEN THE TIDE IS HIGH, SEAWATER FLOWS 3 MILES FROM THE OCEAN INTO A RESERVOIR.

IT'S THEN CHANNELED THROUGH A PATCHWORK OF PONDS, EVERY ONE JUST SLIGHTLY LOWER THAN THE LAST.

AS THE WATER MOVES DOWN FROM ONE POND TO THE NEXT, IT BECOMES MORE CONCENTRATED UNTIL IT'S 10 TIMES AS SALTY AS IT STARTED.

AND THEN FROM THE BRINY WATER, SALT CRYSTALS EMERGE.

SOPHIE: I'M COLLECTING VERY FAMOUS SALT OF GUERANDE, THAT IS CRYSTALLIZING AT THE BOTTOM OF THE POND DIRECTLY ON CLAY.

NARRATOR: THE HIGHLY PRIZED BEAUTIFUL CRYSTALLINE FLAKES OF SALT CONTAIN MORE MOISTURE THAN COMMON SALT, WHICH MEANS THE TASTE LINGERS FOR MUCH LONGER.

AND BEING UNREFINED, OTHER MINERALS LIKE CALCIUM AND MAGNESIUM CHLORIDE GIVE IT A MORE COMPLEX FLAVOR.

IT'S THE TASTE OF THE SEA.

AND THIS IS IT.

THIS IS THE END RESULT.

AFTER BILLIONS OF YEARS, OUR BODIES STILL RELY ON THE SAME BASIC CHEMISTRY THAT EVOLVED IN THOSE FIRST BLOBS OF LIFE IN THE SEA.

NARRATOR: INSIDE THE BODY, SALT CONTROLS THE AMOUNT OF WATER IN EACH CELL.

WHERE THERE'S MORE SALT, WATER WILL GO.

IT'S A PROCESS CALLED OSMOSIS.

IT MAKES CELLS SWELL AND SHRINK.

ELSEWHERE, THE SODIUM IN SALT IS CRUCIAL FOR THE FUNCTIONING OF OUR NERVES.

IT'S THE MOVEMENT OF TRILLIONS OF SODIUM IONS IN OUR BRAIN THAT ALLOWS US TO THINK, MOVE, AND SENSE THE WORLD AROUND US.

AND THESE SODIUM IONS ALSO AFFECT OUR TASTE BUDS... NOT JUST BITTER...

BUT SWEET, TOO.

AS WELL AS THE FINEST SALT, BRITTANY IS ALSO HOME TO CARAMEL AU BEURRE SALE--SALTED CARAMEL.

YOU KNOW, THAT STUFF THAT'S TAKEN THE WORLD BY STORM OVER RECENT YEARS.

WE ARE HARD WIRED TO LOVE SUGAR AND HARD WIRED TO LOVE SALT SEPARATELY.

BUT WHEN YOU PUT THEM TOGETHER, SOMETHING MAGICAL HAPPENS.

NARRATOR: THE SODIUM IN A TINY AMOUNT OF SALT ACTUALLY MAKES SUGAR TASTE SWEETER.

BECAUSE ALONGSIDE OUR REGULAR SWEET RECEPTORS, WE HAVE SOME ADDITIONAL RECEPTORS THAT ARE ONLY ACTIVATED WHEN BOTH SUGAR AND SALT ARE PRESENT.

SO FOR THE MAXIMUM SWEET SENSATION, SEEK OUT THE SALTY TASTE COMBINATIONS FOUND IN ICE CREAM, SWEETS, CHOCOLATE, AND, OF COURSE, THE GOOEY LIQUID FILLING INSIDE A THIN FRENCH PANCAKE--A CREPE.

IT'S NOT POLITE, BUT IT'S DELICIOUS.

NARRATOR: SALT...

BITTER... SWEET...

SOUR... AND UMAMI.

TOGETHER THESE 5 TASTES FORM THE FOUNDATION FOR OUR EXPERIENCE OF FOOD.

MICHAEL: BECAUSE WE PUT FOOD IN OUR MOUTHS, WE TEND TO THINK OF ALL THE ACTION HAPPENING THERE ON THE TASTE BUDS.

BUT IN FACT, WHEN WE EXPERIENCE FOOD, WE ALSO SEE IT, AND CRITICALLY... [INHALES] WE SMELL IT.

AND IT'S ALL OF THAT WHICH ADDS UP TO WHAT WE CALL FLAVOR.

[CATTLE LOWING] NARRATOR: CURIOUSLY FLAVOR ISN'T JUST ABOUT TASTE; IT'S ALSO ABOUT THE NOSE, AND JAMES HAS COME TO BURGUNDY, FRANCE, WHERE THERE'S A KIND OF FOOD THAT IS FAMOUSLY DEFINED BY ITS NOSE: CHEESE.

WHICH IS ODD BECAUSE MOST CHEESE STARTS OUT LIFE THE SAME WAY, SMELLING OF ALMOST NOTHING.

SO THIS IS WHERE IT ALL BEGINS.

FOR SOMEONE WHO'S USED TO KNOWING COWS ON PACKETS IN SUPERMARKETS, IT'S A DOSE OF REALITY FOR ME.

NARRATOR: TO MAKE CHEESE, NATURALLY OCCURRING LACTIC ACID IS ADDED TO FRESH COW'S MILK AND IT'S ALLOWED TO CURDLE.

THEN THE FRAGILE CURDS ARE PUT INTO MOLDS, WHERE THE LIQUID WHEY RUNS OFF.

WOMAN: YOU CAN TAKE MORE CHEESE.

OK, BIGGER SCOOPS?

OUI.

YES.

VERY GOOD.

VERY GOOD.

NARRATOR: THESE CURDS WILL BECOME THE FINISHED CHEESE, BUT IT BEGINS WITH VERY LITTLE TASTE AND NO SMELL.

AND YET FROM THIS BEGINNING, THE FRENCH PRODUCE MORE THAN 400 DIFFERENT KINDS OF CHEESE.

EACH WITH THEIR OWN UNIQUE FLAVOR.

JAMES: OH, HO HO!

THAT'S INTENSE!

IT'S LIKE A FURRY ANIMAL!

NARRATOR: SO HOW DO ALL THESE DISTINCTIVE CHEESES END UP BEING SO DIFFERENT?

MORE THAN ANYTHING ELSE, THE FLAVOR OF EACH CHEESE IS DETERMINED BY THE WAY IT SMELLS.

JAMES: TAKE A BIT OF CHEESE, AND YOU COVER UP YOUR NOSE.

IT MEANS NOW I CAN'T SMELL ANYTHING, BUT I CAN STILL TASTE.

THIS COMTE, WHICH IS NORMALLY INCREDIBLE, IS LIKE EATING A SALTY CANDLE.

YOU HAVE THIS WAXY TEXTURE, YOU HAVE A BIT OF SALT, A BIT OF BITTERNESS, BUT IT'S LIKE EATING IN BLACK AND WHITE.

[SNIFFS] AND IT IS INCREDIBLE.

THE SECOND YOU UNCOVER YOUR NOSE, THIS RUSH OF COMPLEXITY AND FLAVOR COMES BACK.

IT'S LIKE EATING IN TECHNICOLOR.

THE MASSIVE DIFFERENCE BETWEEN THE THOUSANDS OF DIFFERENT TYPES OF CHEESE ON THE PLANET IS ALL ABOUT SMELL.

[BELL TOLLING] NARRATOR: THIS SIMPLE EXPERIMENT REVEALS THE POWERFUL EFFECT SMELL CAN HAVE ON THE FLAVOR OF FOOD.

AND TO BETTER UNDERSTAND HOW EACH CHEESE GETS ITS OWN AROMA, JAMES IS ABOUT TO HAVE AN ENCOUNTER WITH A NOTORIOUSLY PUNGENT ONE.

JAMES: IT'S A CHEESE KNOWN AS THE KING OF CHEESES, NAPOLEON'S FAVORITE, AND ONE OF THE WORLD'S SMELLIEST.

THERE ARE STORIES THAT THIS STUFF SMELLS SO BAD, THAT IT WAS ACTUALLY BANNED FROM THE PARIS METRO.

NICE.

NARRATOR: IT'S A SOFT RIND-WASHED COW'S CHEESE CALLED EPOISSES.

BUT WHAT IS RESPONSIBLE FOR MAKING ITS UNIQUELY POWERFUL SMELL?

FOR IT TO DEVELOP, THE EMBRYONIC CHEESE NEEDS SALT, IT NEEDS TIME, AND IT NEEDS BACTERIA.

EACH CHEESE STARTS ITS JOURNEY OF TRANSFORMATION WITH A SPECIFIC TYPE OF BACTERIA.

BUT IT'S HOW THESE YOUNG CHEESES ARE TREATED NEXT THAT CREATES THEIR FLAVOR AND TEXTURE.

WITH EPOISSES THE RINDS ARE REGULARLY WASHED WITH WATERED DOWN POMACE BRANDY, MADE FROM THE SKIN, SEEDS, AND STALKS OF GRAPES LEFT AFTER WINEMAKING.

WOMAN: IT'S VERY FRAGILE.

YES.

SO YOU TAKE IT SLOWLY.

OK. NARRATOR: THE BRANDY IMPARTS SOME OF ITS OWN FLAVOR TO THE CHEESE BUT MOST IMPORTANTLY, IT AFFECTS WHICH BACTERIA THRIVE ON THE CHEESE.

WOMAN: [SPEAKS FRENCH] TRANSLATOR: NOT TOO HARD, OK?

NARRATOR: ONE KIND OF BACTERIA IS CALLED ARTHROBACTER ARILAITENSIS, WHICH BUILDS LONG-CHAIN MOLECULES THAT MAKE THE RIND GO ORANGE.

ANOTHER IS BREVIBACTERIUM LINENS.

THESE BREAK DOWN THE PROTEINS IN THE CHEESE INTO SMALLER MOLECULES, INCLUDING STINKY SULFUR COMPOUNDS THAT GIVE THE CHEESE ITS FUNKY, SWEATY AROMA.

ITS CLOSELY RELATED COUSIN, BREVIBACTERIUM EPIDERMIDIS, CAN BE FOUND GROWING ON HUMAN FEET, GIVING THEM THEIR FUNKY, SWEATY AROMA.

JAMES: VOILA!

OOF!

THEY WEREN'T KIDDING ABOUT THE, UH, THE WAY IT SMELLS.

IT'S INTENSE.

IT'S KIND OF SULFUR-LIKE.

IT'S KIND OF AN INSTANT FLASHBACK TO THE RUGBY SOCKS I LEFT IN A P.E.

KIT ONCE IN SCHOOL FOR A WHOLE WEEK.

[SNIFFS] NARRATOR: VOLATILE AROMA MOLECULES FROM CHEESE, OR FEET, FLOAT INTO THE AIR, AND GET SUCKED UP INTO YOUR NOSE.

EACH SMELL COMPOUND STIMULATES A UNIQUE COMBINATION OF RECEPTORS THAT ALLOW US TO IDENTIFY THE SMELL.

IN THE CASE OF EPOISSES, IT'S A SMELL OF STINKY FEET THAT'S NOT PARTICULARLY PLEASANT OR APPETIZING.

SO WHY, IF IT SMELLS SO BAD, WOULD ANYONE PUT IT IN THEIR MOUTH?

BUT...WHEN YOU EAT IT, SOMETHING MAGICAL HAPPENS.

THE AROMA COMPOUNDS ARE RELEASED IN YOUR MOUTH, AND THEY WAFT UP THE BACK OF YOUR NOSE.

AND THEY'RE DETECTED THERE BY THE SAME SMELL DETECTORS, BUT WEIRDLY YOUR BRAIN PERCEIVES THEM AS VERY DIFFERENT FROM IF YOU WERE TO SMELL FORWARD AND SNIFF THEM UP THE FRONT OF YOUR NOSE.

NARRATOR: IT'S CALLED BACKWARD SMELLING.

RATHER THAN SIMPLY SMELLING THE STINK, THE BRAIN NOW COMBINES THE SMELL WITH THE CREAMY TASTE IT'S EXPERIENCING ON THE TONGUE AT THE SAME TIME.

THIS COMBINATION OF TASTE AND SMELL HAS A DRAMATIC EFFECT ON HOW WE PERCEIVE A PARTICULAR ODOR MOLECULE.

AND FOR THE FULL EFFECT, ALWAYS EAT THE RIND, SINCE THIS IS WHERE MANY OF THE SMELLS LIE.

THIS STUFF... NO LONGER IS PUNGENT AND KIND OF ANIMALIC LIKE YOUR BODY.

IT'S SUDDENLY SHARP, GARLICKY, EGGY.

IT'S JUST WARMING, COMFORTING DELICIOUSNESS.

NARRATOR: THIS IS THE FULL-FLAVOR EXPERIENCE.

ONLY BY COMBINING TASTE AND BACKWARD SMELLS IN OUR BRAIN DO WE UNLOCK OUR FOOD'S FULL FLAVOR POTENTIAL.

DIMITRIS: BREATHE NORMALLY IN THERE.

NARRATOR: WE MAY HAVE ONLY 5 TYPES OF TASTE RECEPTORS ON OUR TONGUE, BUT OUR NOSES ARE PACKED WITH AROUND 400 DIFFERENT SMELL DETECTORS.

BUT WILL MICHAEL BE ABLE TO IDENTIFY ONE OF HIS FAVORITE MEALS BY SMELL ALONE?

MICHAEL: WHOA, THAT WAS STRONG.

[INHALING] THIS ONE FOR SOME REASON IS MAKING ME THINK OF WET MACKINTOSHES.

NARRATOR: THE TWIST IS MICHAEL'S NOT GOING TO EAT ANYTHING.

MICHAEL: QUITE AROMATIC.

NARRATOR: INSTEAD HE'S GOING TO BE INHALING INDIVIDUAL WAFTS OF EACH AROMA OF THIS MYSTERY MEAL.

MICHAEL: SMELLS ALMOST FECAL.

CAN'T WORK IT OUT WHAT IT IS.

THAT'S WEIRD.

ALMOST ANISEEDY.

SMELLS...

DAMP BASEMENT SMELL.

NOT LIKE YOU CAN SAY THAT'S LEMON OR THAT'S... PINE CONE OR...

THEY'RE SORT OF SPICY.

NARRATOR: IT'S ONLY WHEN ALL THE SMELLS ARE BROUGHT TOGETHER AT THE END OF THE TEST THAT MICHAEL CAN FINALLY TAKE A GUESS.

DIMITRIS: WOULD YOU LIKE TO SMELL THIS ONE?

OK, YEP.

YEAH?

[SNIFFS] WHOA, THAT'S STRONG!

SO THAT IS DEFINITELY CURRY, AND IT SMELLS LIKE ... IS THAT CHICKEN KORMA?

YES, EXACTLY.

YEAH.

WE BROKE DOWN ALL THE AROMA COMPONENTS OF THIS CURRY, AND YOU SMELLED THEM ONE AFTER THE OTHER.

BUT I COULDN'T PUT THEM ALL TOGETHER.

YEAH.

NO.

THERE ARE MANY SPICES, SO YOU CAN GET MANY SPICY NOTE, MANY MEATY NOTES, SOME STRANGE NOTES LIKE ROSE, LIKE POTATO, AND PIGSTY.

HA HA!

PIGSTY WAS AT THE BEGINNING.

YEAH.

YEAH.

IT'S VERY, VERY ODD HAVING THEM AS KIND OF DISTINCTIVE THINGS AND THEN TRYING TO ADD THEM UP TO SOMETHING.

I WOULD NEVER, EVER HAVE GUESSED THAT WAS CHICKEN KORMA.

AND YET WHEN I SMELL THAT, I KNOW STRAIGHTAWAY IT'S CHICKEN KORMA.

IT JUST SMELLS LIKE IT.

IT'S ONE OF THE THINGS I'M QUITE FAMILIAR WITH.

HA HA!

YEAH.

NARRATOR: THIS EXPERIMENT REVEALS HOW OUR NOSES HELP US ENJOY FOOD.

RATHER THAN SINGLING OUT INDIVIDUAL NOTES... ALL THE INDIVIDUAL AROMAS COME TOGETHER TO FORM ONE UNIFIED, INSTANTLY IDENTIFIABLE AND DELICIOUS SMELL.

USING JUST 400 DIFFERENT SMELL RECEPTORS... OUR NOSES ARE SO POWERFULLY TUNED THAT THAT IT'S BEEN ESTIMATED WE CAN IDENTIFY A TRILLION DIFFERENT SMELLS.

LIKE PIZZA, ROAST CHICKEN, OR A FINE RED WINE.

IN OUR SEARCH FOR EVER MORE DELICIOUS AND SATISFYING THINGS TO INDULGE OUR SENSES, WE'VE CREATED EXTRAORDINARY PROCESSES THAT ALTER THE TASTE, TEXTURE, AND AROMA OF OUR FOOD.

MICHAEL HAS COME TO TUSCANY, ITALY, TO EXAMINE THE ONE PROCESS THAT HAS CHANGED THE COURSE OF CIVILIZATION.

IT HAS TRANSFORMED OUR EXPERIENCE AND OUR ENJOYMENT OF FOOD.

IT IS, OF COURSE, COOKING.

NARRATOR: THERE'S EVIDENCE OUR REMOTE ANCESTORS BEGAN COOKING FOOD AT LEAST 400,000 YEARS AGO.

AND FROM THE START THEY WERE UNWITTINGLY TRIGGERING IN OUR FOOD ONE OF THE MOST COMPLEX CHEMICAL REACTIONS ON EARTH.

NOW THIS IS A TRULY WONDERFUL PIECE OF MEAT.

IT'S A LOCAL SPECIALTY KNOWN AS BISTECCA FIORENTINA.

NOW IN ITS RAW STATE LIKE THIS... [INHALES] IT REALLY DOESN'T SMELL OF ANYTHING VERY MUCH, BUT PUT IT ON THE GRILL OVER THERE, SOMETHING TRULY WONDROUS WILL HAPPEN.

IT'S CALLED THE MAILLARD REACTION, NAMED AFTER A FRENCHMAN.

I PREFER TO CALL IT THE SCIENCE OF THE SIZZLE.

[SPEAKING ITALIAN] TRANSLATOR: A GOOD HEAT-- AROUND 180 CELSIUS.

YOU DON'T PUT SALT?

NO, NO, NO.

OIL?

NO.

NOTHING.

THE KEY TO UNLOCKING THE FLAVOR IN THE MEAT IS THE SMELLS THAT WILL BE GENERATED BY THE MAILLARD REACTION.

AND YOU CAN ACTUALLY SEE IT HAPPENING RIGHT BEFORE YOUR EYES.

MICHAEL: SO ALL THIS LOVELY BROWN STUFF YOU CAN SEE OVER HERE, THAT IS THE RESULTS OF THE MAILLARD REACTION.

NARRATOR: IT STARTS OFF SIMPLY ENOUGH.

IN THE INTENSE HEAT, THE BUILDING BLOCKS OF PROTEIN, THE AMINO ACIDS, REACT WITH NATURALLY OCCURRING SUGARS IN THE MEAT.

AND THE BEAUTY OF THE MAILLARD REACTION IS THAT ONCE IT KICKS OFF, EVERYTHING GOES COMPLETELY CRAZY.

NARRATOR: THE REACTION BECOMES MORE AND MORE COMPLEX AND INTENSIFIES AS THE PRODUCTS OF EACH REACTION GET INVOLVED IN THEIR OWN REACTIONS.

EVENTUALLY, THE WHOLE THING CASCADES WILDLY AND GENERATES THOUSANDS OF DIFFERENT MOLECULES.

LOTS OF... [INHALES] LOVELY AROMA MOLECULES THAT I AM NOW... [INHALES] HUNGRILY HOOVERING UP.

[SPEAKS ITALIAN] TRANSLATOR: A BEAUTIFUL AROMA.

SMELLS ABSOLUTELY FANTASTIC NOW I HAVE TO SAY.

COMPLETE TRANSFORMATION FROM THAT PIECE OF MEAT AS IT WAS INTO WHAT IT IS NOW.

[SPEAKS ITALIAN] TRANSLATOR: ADD PLENTY OF SALT.

OIL.

OK, OLIVE OIL, SPLASH ON.

[SPEAKS ITALIAN] TRANSLATOR: NOW WE CARVE IT INTO THICK PIECES.

IT'S PERFECT.

PERFECT.

PERFECT.

[SPEAKING ITALIAN] TRANSLATOR: A TRUE BISTECCA FIORENTINA.

NARRATOR: AND IT'S NOT JUST ABOUT MEAT.

BAKING BREAD... ROASTING COFFEE... FRYING ONIONS AND GARLIC.

IF IT SMELLS GOOD WHEN YOU COOK, THE SECRET CHEMIST INSIDE YOU IS ACTUALLY ANALYZING THE RESULTS OF A MAILLARD REACTION.

A REACTION SO COMPLEX IT WOULD TAKE UP AN ENTIRE BOOK TO DESCRIBE IT.

ALL: HEY!

NARRATOR: OUR UNDERSTANDING OF FOOD AND HOW IT SEDUCES OUR SENSES IS DEEPENING ALL THE TIME.

IN THE PAST, WHEN EATING THE WRONG THING COULD BE A THREAT, OUR SENSES GUIDED US TO SWALLOW WHAT WAS NOURISHING AND TO SPIT OUT WHAT MIGHT HARM US.

FOR MODERN HUMANS, THOUGH, TASTE IS NO LONGER MERELY A GUIDE TO SURVIVAL.

TODAY, WE TRANSFORM FOOD IN WAYS THAT OUR ANCESTORS WOULD NEVER HAVE RECOGNIZED... TO CREATE COMBINATIONS THAT STIMULATE OUR EYES, NOSES, AND ALL OUR TASTE BUDS TO CREATE THE ULTIMATE MOUTHFUL OF FLAVOR.

MICHAEL: THESE DAYS, TASTE IS MAINLY ABOUT PLEASURE AND THE ENJOYMENT IN FOOD.

AND IT'S THAT ENJOYMENT WHICH BRINGS COMMUNITIES AND FAMILIES TOGETHER.

IT'S BECAUSE WE REALLY UNDERSTAND WHAT MAKES FOOD WORK THAT WE'RE ABLE TO CREATE UNUSUAL COMBINATIONS, REALLY MAKE OUR TASTE BUDS ZING.

NARRATOR: NEXT TIME WE'LL EXPLORE THE FOODS WE SIMPLY CANNOT LIVE WITHOUT.

THIS IS REAL AZTEC GOLD.

NARRATOR: WE'LL DISCOVER HOW WHAT WE EAT BUILDS OUR BODIES AND KEEPS US HEALTHY.

MICHAEL: IN FACT, IT IS ABSOLUTELY VITAL FOR BUILDING AND MAINTAINING MY FAVORITE ORGAN, THE BRAIN.

NARRATOR: AND WHY WHAT'S IN OUR FOOD IS ESSENTIAL TO OUR SURVIVAL.

JAMES: IT'S GOT TO BE THE WORLD'S BEST COMFORT FOOD.

"FOOD: DELICIOUS SCIENCE" IS AVAILABLE ON DVD.

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