Taste: Your Brain on Food

1. Tasting is Testing 2

To taste is to test.Like or dislike.We are not born liking fruit on the tree of good and evil;or on any other tree. We learn by tasting. Only a few taste judgments seem “built-in,” Or “genetically determined.” Infants scrunch their faces and make escape moves when tasting bitter or sour. 4

Infants seem intent on exploringthe world by tasting everything.Until about two years of age, kidstreat the world as possible food.The distinction between “food”and “nonfood” is learned fromparents and cultures.Around age two or three kidsoften become neophobic -- theyshow great distrust for newand/or unfamiliar foods. Theyalso discover that some things aredisgusting. This makes sense fromthe viewpoint of human survivalsince it occurs at the age whenchoices in what to eat firstemerge. To distrust the unfamiliaris a protective strategy. 5

Humans ARE born with a“sweet tooth.”Of course, it has nothing to dowith teeth.Babies show a preference forsweetened water after only afew hours of life.We prefer the sweet because weneed sugar to live.Your blood contains about aTeaspoon of sugar in the formof glucose. 6

Your brain is a three pound mass ofelectro-chemical activity that uses asurprising twenty percent of allcalories you eat. Thinking really ishard work.Only one fuel works to fire thosebrain neurons – sugar (specifically,glucose). No wonder we cravesweets. Neurons can’t store sugar,they need a constant supply fromthe bloodstream.The reason behind our tastepreferences are invisible to us;buried in the distant past of ourspecies. You simply enjoy the taste. PET scan of normal brain.Sweet. 7

Eating is our most intimateexchange with the environment. Ineating we allow the world “outthere” to become part of the self. Sowe avoid tasting foods that mightmake us disgusting. We fear wewill become what we eat.You would find a cockroachdisgusting, but you probably don’tknow how it tastes. Disgust istriggered by the mere idea of tastingthe substance. Your expectation isenough to trigger disgust. 8

Volunteers in a an experimentwatched researchers pour ordinarytomato juice into a clean jar labeled“red blood.” Even thoughparticipants knew the liquid was“only tomato juice” theyexperienced various degrees ofdiscomfort in drinking the juice.Many simply refused. 9

Even food that looks likesomething offensive isdisgusting.Let’s say you are asked toeat a piece of fudge likethis.You know it’s just fudgeand that it tastes good.But that knowledge mightnot prevent you fromgagging or becomingnauseous. 10

Most people would be uncomfortable or would refuseto drink soup out of a bed pan, even though they knowit is brand new and sterile. 11

Disgust is food based but we also apply it in the world of non-food aswell. We taste the world…. 12

Taste is a bit like color. The skin of an apple appearsred, but an apple does not “have” flavor any more thanit “has” red. Taste, like color, only “happens” uponinteracting with your senses. Taste is your perception.Taste is multi-sensory. A “flavor” is a perception weconstruct from taste buds, eyes, nose, and feelings in themouth. 13

Cook a nice fish filet foryour friends. After theytell you how good it was,tell them the “fish” theyenjoyed is snake or eel.The knowledge of whatthey ate might cause realphysical distress.It’s not so much the fruitthat hangs on the tree thatwe taste, it’s theknowledge of good orevil.We taste our beliefs andexpectations. 14

2. Tasting with your eyesThe flavor we experience isshaped by our expectations.One of the clearest influences isour expectation of how the food“should look.” Tasting oftenbegins with the eyes.During one experiment in theearly 1970s people were servedblue fries and green steak butate them in colored lights thatmade the food appear normalin color. Subjects thought themeal tasted fine until thelighting was changed. Once itbecame apparent they wereeating blue fries and greensteak, some people became ill. 15

In another study, peopletasted orange juices thatdiffered only in color(lighter or darker shades oforange) and degree ofsweetness.Given two glasses of thesame orange juice, one adarker orange than theother, the tasters judged thedarker colored juice to besweeter.Surprisingly, when giventwo glasses of orange juicethat were the same color,but differing degrees ofsweetness, the testers didNOT perceive a differencein taste. 16

People who taste test fruit drinks can easily identify cherry,orange, lime, and grape. But researchers find that tasting whileblindfolded lowers correct flavor identifications to as little astwenty percent.If instead of a blind taste test, subjects are given drinks with thecolors switched (lime flavor colored orange, grape juice coloredred, etc.) correct identification suffers even more. The perceptionof flavor is shaped by color.When water is colored orange, most people experience an orangeflavor. If an orange drink is colorless, many find it tasteless. 17

Even the package in which thefood is presented influences ourperception of taste.Volunteer taste testers rated rootbeer in dark glass bottles as richertasting than the same drink servedin clear bottles.Market researchers for 7Up testeddifferent colored backgrounds oncans and discovered a yellowbackground led testers to report anunusual “lemony” flavor to thesoda. Those who drank from canswith a green background notedadditional lime in the soft drink. 18

The orange of a salmon comes from a diet rich inorange colored algae. Since farm raised salmon don’teat the algae, they remain white like most other fish.But consumers will not accept white salmon.Marketers fear they would claim it “doesn’t taste likesalmon.”So orange food coloring (in the form of beta carotene)is added to satisfy the color expectations ofconsumers. 19

In another experiment, subjects drank cherry-flavoreddrinks and reported that juices with more red colortasted stronger and had more “true” cherry taste. Theeffect was stronger with senior citizens than with youngertasters. Food marketers know that people expect cherryor strawberry flavored foods to be bright red. Omit theadded coloring and consumers complain the food istasteless. 20

Consumers expect American cheese to be darkyellow, even though that is not its “natural”color.The “natural” color of margarine is a pasty white,so coloring is added to make it appear more likebutter. Butter itself is often colored pale yellowto fit expectations.Consumers expect egg yolks to be rich orange.So chickens are given feed with coloring (oftenfrom marigold petals) to insure the eggs “look”(and taste) as expected. 21

Marketers know that consumers judge beef andtuna as fresh only if it is red. Consumers shunbrown beef or gray tuna even if fresh.So meat sellers keep beef and tuna red longerby pumping a gas mixture into sealed packagescalled “modified atmosphere packaging.” Themix includes gases found naturally in air(carbon dioxide and nitrogen) as well as a tinyamount of carbon monoxide. Carbonmonoxide helps delay the natural color changeof meat from red to brown.Retailers defend the process claiming they loseat least a billion dollars by having to throwaway or devalue perfectly good meat thatdoesn’t look red. Consumers suspect retailersuse the process to make old meat look fresh. 22

Researchers at Cornell Universityadded titanium dioxide (a brightwhite coloring approved for use infoods) to skim milk. They foundpeople judged it to be smoother,better tasting, and higher in fat thanthe uncolored milk.We taste a perception based onmultiple sensory input – colorincluded. People who say the“whiter” milk “tastes creamy” areaccurately reporting a perception.Consumers might say “I don’t wantartificial colors in my food,” yetthey buy those colored foodsbecause they perceive them astasting better. By “givingconsumers what they want” thefood industry reinforces the “color-equals-taste” illusion. 23

3. Feel Influences Taste Mouthfeel-- the sensation food creates in the mouth--is a key part of taste. Mouthfeel includes qualities such as a food’s moisture, gumminess, crispness, viscosity, slipperiness, brittleness, temperature, and weight. For example, chocolate has to have the right degree of “snap,” and ice cream just the right degree of gumminess. Food marketers know if a food feels “wrong,” eaters will judge it tastes “wrong” as well. 24

Dr. Francis McGlone, a neurosceintist at Unilever (maker ofBen & Jerry’s ice cream) knows something about the brain onice cream. He says:"Flavor is not as simple as the way it tastes. The other senses….candominate the way the brain interprets a food. Ice cream activates apart of the brain known as the orbitofrontal cortex, which is justbehind the eyes and is where emotions are processed. By melting, icecream changes its physics and creates contrasts that continuallykeep your senses interested.”In other words, the feel of melting is part of the “taste.” 25

We often describe ice cream, custard, pudding, or sauces ashaving a creamy taste. That “creaminess” is more about howthe food feels in the mouth than about actual cream content.Studies find people judge foods as creamier when they sensethem to be thick, provide significant mouth coating, are denseand slow to melt. Cooks and food designers usestarches, thickeners and emulsifiers to help create that“creamy” taste.     A sauce can taste “creamy” without actually containing cream. 26

To say a food tastes “light andcrispy” is to make a judgmentabout mouthfeel.Packaging can change theperception of a food’s“crispiness.” Studies suggest thatpeople biting into potato chips(Pringles) rate the chips as 15%fresher when the sounds arelouder, or when the highfrequency components of thebiting sounds (above 2KHz) areboosted.Other studies show we judgefood in noisy packages to becrisper than the same foods in“quiet” packages. 27

We love the mouthfeel of fattyfoods. Fat gives food apleasing “body,” andcontributes to a sense offullness in the mouth.We don’t eat over twenty-eight pounds of french friesper person each year becausewe love the taste of potatoes.We eat fries, fish sticks, onionrings, doughnuts, chickennuggets, and potato chipsbecause their high fat contentmakes them feel good in themouth. They are sensation-filled. 28

The combination of a crispy outside with a softerfat/sugar inside is a “melt in your mouth”sensation found in many processed foods fromfried shrimp to stuffed doughnuts, ice cream bars,fried fish, toast and butter, chicken nuggets, eggrolls, machos, and buffalo wings. They are to themouth what fireworks are to the eye. 29

Temperature is also part of mouthfeel. Heat by itself opens the taste receptors for sweetness, even when no taste is present. Touching the tongue with a warm or cold probe willWarming an apple pie can create the perception trigger a taste sensation inof a sweeter pie. about half the people. 30

But letting ice cream meltcompletely leaves it tastinglike overly sweet milk.Taste tests in whichparticipants are asked tojudge liquids need carefulcontrols for temperature.The warmer liquid will tastea bit sweeter. There might bemore taste differencebetween a warm Coke andcold one than between aCoke and a Pepsi served atthe same temperature. 31

We call spicy foods “hot,” but not because of temperature. The heatwe feel from spicy food is not a message from our taste buds. Somespices activate our pain receptors. We “feel” the pain of spice as heatand treat it as part of the taste multi-sense.Capsaicin--the chemical found in chili peppers--produces the illusionof heat. It might be more accurate to say foods “feel” spicy than thatthey “taste” spicy. 32

Menthol triggers cold receptors in the mouth to createthe very real illusion of coolness.Neither menthol nor capsaicin actually changes skintemperature even though they feel warm and cool. Menthol is made synthetically or obtained from peppermint or other mint oils. 33

Think about spicy foods you’ve eaten and youmight recognize two distinct varieties: one youfeel in your mouth and the other in your nose.The molecules in chilies and black peppers arelarge and heavy – they tend not to escape up ournose – we “taste” them mainly in the mouth.Mustard plants (that includes horseradish andwasabi) release a small molecule when the plantis damaged (sort of like the plant version of askunk), so it easily escapes from the food andenters the nose.So you sense a jalapeno in the mouth and wasabiin the nose but you call both “spicy” or “hot.” 34

4. Tasting Expectations 35

MIT psychologists conducted a taste experiment in which they asked barpatrons to taste a beer they called “MIT brew” – regular beer with a fewdrops of balsamic vinegar. In blind taste tests, people preferred thealtered beer.The experiment used two groups of tasters – one was told about thevinegar BEFORE they drank the beer, the other group learned about thevinegar only AFTER the taste test.Those who knew about the vinegar flavoring rated the beer much worsethan those who learned only after drinking. The belief that vinegar andbeer don’t mix shaped the drinker’s taste perception. 36

One study asked people to rate thetaste of plain Seltzer water andPerrier. Researchers found thatpeople preferred the Perrier whenthe waters were labeled, butshowed no clear preference whenthe labels were removed. 37

Other researchers foundstrawberry yogurt and cheesespreads are rated as less tastywhen labeled “low fat.” Another study found that describing the protein of energy bars as “soy protein” caused eaters to describe the taste as more grainy and less flavorful than when the word “soy” was NOT used. 38

At the Center for TheoreticalNeuroscience at Baylor College ofMedicine , sixty-seven people tried ablind taste test of Coca-Cola andPepsi. About half chose Coke andhalf Pepsi.But when the subjects were told theywere drinking Coke, over 70% saidCoke tasted better. Magnetic imagingof their brans showed that when thetasters knew they were drinking Cokethey used brain areas relating tomemories and impressions that werenot used during the blind taste tests.The results suggest that thepreference for a favored brand(Coke, in this case) is shaped bymemories and expectations . 39

In 1985, Coca-Cola attempted to introduce a “new andimproved” Coca-Cola. Using nationwide blind taste teststhey found that people liked the slightly tweaked “newCoke” better than both the “old” Coke and Pepsi.But after rolling out the “New Coke,” people stubbornlyinsisted they preferred the “old” taste. Blind taste tests donot mimic real life. In a lab, tasters judge by taste. In thereal world, we judge by labels and expectations.The new Coke lacked a bias about how it “should” taste.Consumers suddenly “tasted the vinegar in the beer”and decided it was not so good after all. 40

One clever study askedchildren to rate the taste ofcarrots, milk, and apple juice.In one group, the foods wereserved in unmarked wrappers.In the other, the same foodswere wrapped in McDonaldspackaging. The unmarkedfoods always lost the taste test.Study author Dr. TomRobinson noted theirperception of taste was"physically altered by thebranding. Kids don’t just askfor food fromMcDonald’s, they actuallybelieve that the chicken nuggetthey think is from McDonald’stastes better than anidentical, unbranded nugget.” 41

Researchers at Stanford andCal Tech had people sip winewhile an fMRI machinemeasured brain activity.Volunteers sipped variouswines including the same redwine twice. For one tasting,volunteers were told the winesold for $5 a bottle (the actualprice), but the second time theywere told it was a $45 wine.The subjects said they likedthe expensive wine better.The increased preference wasseen as increased activity in theprefrontal cortex. The subjectsreally did enjoy the expensivewine more. 42

A study gave consumers a choiceamong three jars of peanut butter. Ina blind taste test, one brand won“best tasting” 60% of the time -- aclear winner.Next, researchers tested the samechoices but with labels on the jars.One label was a well-known, heavily-advertised national brand, while theother two were unknown brands. Inthis test, the peanut butter that wonthe original taste test was in a jar withan unfamiliar label. Would it still winthe taste test?Nope. This time, 73% chose thelower-quality spread with the well-known brand name. Only 20% chosethe high-quality product in theunfamiliar jar. 43

Psychologists use the term “expectation bias” todescribe our tendency to taste, hear, and seewhat we expect.The orange juice really will taste better if it isbright orange, the wine will taste more full-bodied and complex if it costs more. The Coca-Cola and peanut butter will taste worse from anunlabeled source than from one marked with afamiliar brand, and kids will find that applestaste better if they come from a bag with theMcDonald’s logo. We see, hear, taste, and feelour expectations. 44

5. Culture shapes tastesWe define ourselves in part by what wetaste. People who eat like us areprobably “Us” while those who eatstrange and disgusting foods are clearly“Them.”By the time we reach age eight ourculture has shaped our tastes. But culture Ground horsemeatto the individual is like water to a fish.We see cultural differences in otherseasily, but the influence of our ownculture often remains invisible. We feel abit uneasy in the presence of people whoeat things we do not consider food.We spend millions to buy food for cats,dogs, and horses but consider it nearlyinhuman to buy cats, dogs, and horses Cooked dogfor food. 45

Tastes change. A hundred and fifty years ago Americans didn’t drink much fresh milk (most milk was consumed as cheese or butter), most apples were sour and consumed in liquid form as hard cider. Soft drinks were more medicine than refreshment, many vegetables (raw tomatoes, for example) were considered risky, bananas were an exotic curiosity (in 1899, Scientific American ran an article showing how to peel a banana), yogurt was nearly unknown in the U.S., and ethnic food was considered unhealthy or disgusting. Chicken was a food for special occasions.At the Philadelphia Centennial Exposition of1876, curious fair goers could try a banana wrapped intinfoil for ten cents. It was quite a novelty. Milk has long been viewed as a dangerous food. 46

Four and twenty blackbirds bakedin a pie is not merely a line in anursery rhyme – it’s a recipe.Blackbird pie? Did people reallyeat song birds. Yes. To discoverwhy we eat mostly chicken andignore most other birds requires abit of history. 47

Many cultures eat allsorts of small birds. Abird on a stick iscommon street food inChina.Surprisingly, chickenas an ordinary food isa relatively modernidea. 48

In 18th and 19th century America,dining on a bird meant a youngpigeon. These “squabs” werenot the pigeons we see in today’surban downtowns, nor werethey carrier or homing pigeonsused as our first airmail.They were a completelydifferent species – a wild birdcalled the passenger pigeon,named after the French word for“passage” meaning migratory.Their numbers during migrationhundreds of years ago strainsthe belief of today’s urbandwellers. 49

A flock of passenger pigeons could darken aMidwestern sky for most of a day. The flocks were sothick that a single shotgun shot could bring downthirty or forty birds. Many were killed simply byswatting at them with wooden bats as they flew overhilltops or by stringing nets. 50

When Europeans first arrived in NorthAmerica, they shared the “new world”with about five BILLION passengerpigeons – a number nearly equal to thetotal of ALL birds today in the UnitedStates.Fast growing east coast cities neededfood and passenger pigeons made for aconvenient supply. On just one day in1860, over 235,000 birds were sent eastfrom Grand Rapids, Michigan. In 1869,Van Buren County, Michigan shippedseven million, five hundred thousandbirds back east. If drive-up windowsexisted in the 19th century, they wouldhave offered fried squab, pigeon nuggets,and songbird stew. 51

With such an abundance there seemed no need to conserve. But the “tragedy of the commons” worked its inevitable math and Americans shot, clubbed, and ate the squabs into extinction. The last passenger pigeon in the world died in a Cincinnati zoo in 1914.The last wild Passenger Pigeon was shot by a 14-year old boy in Ohio in 1900. The last PassengerPigeon was nicknamed “Martha” after Martha Washington and died in 1914 in the Cincinnati zoo. 52

We didn’t we eat lots of chicken before the 1950s because chickens weremore valuable for their eggs. A good eating chicken was a seasonalluxury costing as much per pound as a good steak.The USDA and meat producers eventually learned how to produce atasty and reasonably priced chicken – but only after years of breedingtrials and errors. These “chickens of tomorrow” had more meat, largerbreasts, and thicker legs than their scrawny ancestors. 53

Only with the advent of mass scale processing in the 1950s didchicken become a constant presence on our culture’s unwrittenmenu. In 1945, per capita chicken consumption was only fivepounds yearly, by 1960 it was over 25 pounds.The taste of today’s chicken would be unfamiliar to most of ourgreat grandparents. The taste of a culture can change with time. 54

6. How do we taste?The function of taste and smell is to detect chemicals. We speakof tasting “food,” but what we really taste are the chemicals.Taste is chemistry on the tongue. Flavor is perception in the brain. A “chemical free” food would be tasteless. Vanilla contains over two hundred fifty chemicals, coffee over eight hundred. That’s why they have complex yet “heavenly” tastes 55

The actual organ of taste is called the "taste bud." Each taste bud(you have nine or ten thousand in your mouth) contains betweenfifty and one hundred fifty receptor cells. Receptor cells live foronly a week or two before they are replaced by new ones.Each receptor in a taste bud responds best to one of the five basictastes: salty, sweet, sour, bitter, and savory. 56

SavorySavory (often called by itsJapanese name umami) istriggered by the aminoacids glutamate andaspartate in cheeses,mushrooms, somevegetables, meats, andMSG. Umami is a pleasant“brothy” or “meaty” taste. Glutamate is naturally present in a many foods, especially mushrooms, beef, cabbage, and tomatoes.It was recognized as a basic A pizza (tomato sauce, sausage, cheese, mushrooms) is high in glutamate content. It’s very savory.taste only in 1985.Our first experience withumami is breast milk. Itcontains about the sameamount of umami as broth. 57

SweetSweetness signals easy calories – fast energy. We are geneticallypredisposed to seek sweetness -- it’s not a result of poorparenting. You can detect sweetness if only one part in twohundred is sweet – that’s about one teaspoon of sugar in two 58gallons of water.

Today, about a third of the worlds table sugar is from beets. If you grew up before the 1980s, you grew up eating mainly cane and some beet sugar.A bag of “pure sugar” could be made from cane or beets.Not only do they taste the same, they are chemically identical. 59

But if you grew up after the mid 80s, you probablyate more sugar from corn. Beginning in 1980, largebeverage companies began using corn syrup tosweeten soft drinks.Today, corn sweetener is widely used in foods andbeverages. Look on ingredient lists for corn syrup,corn sugar, or high fructose corn syrup – sometimesshortened to HFCS. 60

Many believe cane sugar tastes better than corn sweetener. Yetblind taste tests usually show no clear preference. Butremember that taste is not merely about detecting molecules.Flavor is a perception based on our beliefs and expectations. Ifwe believe “natural," or “organic,” or “cane sugar” is better, itwill taste betterSome beverage makers replaced corn syrup with cane or beetsugar (sucrose) and explained the change as about “deliveringgreat taste.” Kosher Coca-Cola does not contain HFCS. 61

SaltyBabies show a preference for saltywater – humans need salt to live.Blood, sweat, and tears are all salty.Blood holds about as much salt asocean water.We can taste salt in water at aconcentration of a teaspoon inten quarts. Salt sensitivitydeclines with age. At age60, double that con-centration is needed to be tasted.Almost every fluid in your bodycontains salt. Your body holdsabout seven tablespoons of salt.*You lose salt constantly and cannotstore it, so you need salt every day. 62

Popcorn, pretzels, and potato chips taste so salty because the grainsof salt lie mainly on the surface of the food. They taste salty butcontain less sodium than many canned soups or even some bakedgoods. Two slices of white bread have about 270 milligrams ofsodium, the same as a 1.5 ounce bag of potato chips. An ounce ofcorn flakes contains about twice as much sodium as a strip of bacon. 63

SourWhat we call a “sour” taste isour ability to sense acidity.We need to sense sour to keepus away from foods that mightupset our body chemistry anddestroy cells in our gut. Theabilities to taste both bitter andsour seem clearly protectivestrengths.Tasting acidity also helps usjudge the ripeness of food.Fruit, for example is lessnutritious sourthan when sweet. 64

Bitter In our evolutionary past, bitterness signaled a possible toxin. That explains why you can detect bitterness in only one part in two million. Both salt and sugar neutralize or mask bitterness. A little bit of sugar DOES help the medicine go down. Grind the center of the cacao bean and you get a thick liquid known as unsweetened chocolate. It’s also called bitter or baker’s chocolate. Sugar has been used since the 16th century to cut the bitterness. 65

People vary in their ability to taste. One in four is a “supertaster.”Supertasters have more taste buds per square centimeter. About 25% arenon-tasters, and the remaining 50% fall between. “Super tasting is inherited,much like having freckles, curly hair, or being right or left handed.Supertasters often find dark, leafy greens (broccoli, brussels sprouts,cabbage) too bitter and grapefruit too acidic. They experience hot spices,sugar, citric acid and sodium chloride as more intense. They are less likely tosmoke because of the bitter taste of nicotine, and avoid the bitter taste ofcaffeine in coffee or blunt it with cream and/or sugar. Non-tasters findtastes less intense. They are often easier to please in food choices. 66

The sense of smell accounts for as much as 80% of flavor.Without a sense of smell you would find it difficult to tell thedifference between coffee or tea, red or white wine, grated appleand grated onion. Our sense of smell makes an apple taste like anapple rather than a pear or turnip. If your smell is impaired (by acold, for example), food tastes bland, but you can still sense thefour basic tastes. You could sense a jelly candy is sweet, but youcould probably not tell lemon from orange. 67

You think of smell as enteringyour nose from the outside –sniffing the air.But most of the odor involved intasting works from the insideout – it’s called retronasal odor.Odors enter your nasal passagethrough the back of your mouthand rides the air you exhale orswallow. You don’t consciouslyinhale these odors, so you do notexperience them as smells – theyare simply part of the flavor. 68

Our own feelings are part of our brain’s construction of taste. Ourability to taste diminishes when we feel stressed or anxious.Taste is not constant during a lifetime. How food tastes changesaccording to our mood and even with passing emotions. If we feelbetter, food tastes better. Food eaten with friends, soft lighting, andan attractive table setting will really taste better than the same foodeaten in a lunch room while dreading an upcoming test or meeting. 69

If we taste what we expect, what is the effect of growing up eating somany foods with artificial colors and flavors? Do kids learn fromexperience that “orange” is the taste of a frozen orange dessert, and cherrythat sweet flavor found in bottles of red juices?Could kids today grow up never learning what a real orange or cherrytastes like? Given a real cherry and expecting the taste of artificial cherry,might they decide the real thing tastes “weird” and reject it because it isunfamiliar and contrary to expectations?After all, what tastes best is what you’re used to, even if it comes from afactory instead of a farm. 70

The End 71

Taste: Your Brain on Food

by Jeff Schrank on Oct 30, 2011

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Taste: Your Brain on Food — Presentation Transcript