Copyright 2012, Jeffrey Schrank1

Taste:Your Brain On Food

2

It began with a taste...

1. Tasting is Testing

3

Try it, Adam. Just one taste.

You’ll never know unless you try.

4

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.

5

Infants seem intent on exploring the world by tasting everything. Until about two years of age, kids treat the world as possible food. The distinction between “food” and “nonfood” is learned from parents and cultures.

Around age two or three kids often become neophobic -- they show great distrust for new and/or unfamiliar foods. They also discover that some things are disgusting. This makes sense from the viewpoint of human survival since it occurs at the age when choices in what to eat first emerge. To distrust the unfamiliar is a protective strategy.

6

Humans ARE born with a “sweet tooth.”

Of course, it has nothing to do with teeth.

Babies show a preference for sweetened water after only a few hours of life.

We prefer the sweet because we need sugar to live.

Your blood contains about aTeaspoon of sugar in the formof glucose.

7

Your brain is a three pound mass of electro-chemical activity that uses a surprising twenty percent of all calories you eat. Thinking really is hard work.

Only one fuel works to fire those brain neurons – sugar (specifically, glucose). No wonder we crave sweets. Neurons can’t store sugar, they need a constant supply from the bloodstream.

The reason behind our taste preferences are invisible to us; buried in the distant past of our species. You simply enjoy the taste.

Sweet.

PET scan of normal brain.

8

Eating is our most intimate exchange with the environment. In eating we allow the world “out there” to become part of the self. So we avoid tasting foods that might make us disgusting. We fear we will become what we eat.

You would find a cockroach disgusting, but you probably don’t know how it tastes. Disgust is triggered by the mere idea of tasting the substance. Your expectation is enough to trigger disgust.

9

Volunteers in a an experiment watched researchers pour ordinary tomato juice into a clean jar labeled “red blood.” Even though participants knew the liquid was “only tomato juice” they experienced various degrees of discomfort in drinking the juice. Many simply refused.

10

Even food that looks like something offensive is disgusting.

Let’s say you are asked to eat a piece of fudge like this.

You know it’s just fudge and that it tastes good. But that knowledge might not prevent you from gagging or becoming nauseous.

11

Most people would be uncomfortable or would refuse to drink soup out of a bed pan, even though they know it is brand new and sterile.

12

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

He’s so sweetThe bitter end

Leaves a bad tasteIn poor taste

Ended on a sour noteThe design was blandThat’s hard to swallow

The taste of victory

13

Taste is a bit like color. The skin of an apple appears red, but an apple does not “have” flavor any more than it “has” red. Taste, like color, only “happens” upon interacting with your senses. Taste is your perception.

Taste is multi-sensory. A “flavor” is a perception we construct from taste buds, eyes, nose, and feelings in the mouth.

14

Cook a nice fish filet for your friends. After they tell you how good it was, tell them the “fish” they enjoyed is snake or eel.

The knowledge of what they ate might cause real physical distress.

It’s not so much the fruit that hangs on the tree that we taste, it’s the knowledge of good or evil.  We taste our beliefs and expectations.

15

The flavor we experience is shaped by our expectations. One of the clearest influences is our expectation of how the food “should look.” Tasting often begins with the eyes.

During one experiment in the early 1970s people were served blue fries and green steak but ate them in colored lights that made the food appear normal in color. Subjects thought the meal tasted fine until the lighting was changed. Once it became apparent they were eating blue fries and green steak, some people became ill.

2. Tasting with your eyes

16

In another study, people tasted orange juices that differed only in color (lighter or darker shades of orange) and degree of sweetness.

Given two glasses of the same orange juice, one a darker orange than the other, the tasters judged the darker colored juice to be sweeter.

Surprisingly, when given two glasses of orange juice that were the same color, but differing degrees of sweetness, the testers did NOT perceive a difference in taste.

In other words, color changed the taste more than sugar.

17

People who taste test fruit drinks can easily identify cherry, orange, lime, and grape. But researchers find that tasting while blindfolded lowers correct flavor identifications to as little as twenty percent.

If instead of a blind taste test, subjects are given drinks with the colors switched (lime flavor colored orange, grape juice colored red, etc.) correct identification suffers even more. The perception of flavor is shaped by color.

When water is colored orange, most people experience an orange flavor. If an orange drink is colorless, many find it tasteless.

18

Even the package in which the food is presented influences our perception of taste.

Volunteer taste testers rated root beer in dark glass bottles as richer tasting than the same drink served in clear bottles.

Market researchers for 7Up tested different colored backgrounds on cans and discovered a yellow background led testers to report an unusual “lemony” flavor to the soda. Those who drank from cans with a green background noted additional lime in the soft drink.

 

19

The orange of a salmon comes from a diet rich in orange colored algae. Since farm raised salmon don’t eat 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 like salmon.”

So orange food coloring (in the form of beta carotene) is added to satisfy the color expectations of consumers.

20

In another experiment, subjects drank cherry-flavored drinks and reported that juices with more red colortasted stronger and had more “true” cherry taste. The effect was stronger with senior citizens than with younger tasters. Food marketers know that people expect cherry or strawberry flavored foods to be bright red. Omit the added coloring and consumers complain the food is tasteless.

21

Consumers expect American cheese to be dark yellow, 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 like butter. Butter itself is often colored pale yellow to fit expectations.

Consumers expect egg yolks to be rich orange. So chickens are given feed with coloring (often from marigold petals) to insure the eggs “look” (and taste) as expected.

22

Marketers know that consumers judge beef and tuna as fresh only if it is red. Consumers shun brown beef or gray tuna even if fresh.

So meat sellers keep beef and tuna red longer by pumping a gas mixture into sealed packages called “modified atmosphere packaging.” The mix includes gases found naturally in air (carbon dioxide and nitrogen) as well as a tiny amount of carbon monoxide. Carbon monoxide helps delay the natural color change of meat from red to brown.

Retailers defend the process claiming they lose at least a billion dollars by having to throw away or devalue perfectly good meat that doesn’t look red. Consumers suspect retailers use the process to make old meat look fresh.

23

Researchers at Cornell University added titanium dioxide (a bright white coloring approved for use in foods) to skim milk. They found people judged it to be smoother, better tasting, and higher in fat than the uncolored milk.

We taste a perception based on multiple sensory input – color included. People who say the “whiter” milk “tastes creamy” are accurately reporting a perception. Consumers might say “I don’t want artificial colors in my food,” yet they buy those colored foods because they perceive them as tasting better. By “giving consumers what they want” the food industry reinforces the “color-equals-taste” illusion.

24

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.

25

Dr. Francis McGlone, a neurosceintist at Unilever (maker of Ben & Jerry’s ice cream) knows something about the brain on ice cream. He says:"Flavor is not as simple as the way it tastes. The other senses….can dominate the way the brain interprets a food. Ice cream activates a part of the brain known as the orbitofrontal cortex, which is just behind the eyes and is where emotions are processed. By melting, ice cream changes its physics and creates contrasts that continually keep your senses interested.”

In other words, the feel of melting is part of the “taste.”

26

We often describe ice cream, custard, pudding, or sauces as having a creamy taste. That “creaminess” is more about how the food feels in the mouth than about actual cream content.

Studies find people judge foods as creamier when they sense them to be thick, provide significant mouth coating, are dense and slow to melt. Cooks and food designers use starches, thickeners and emulsifiers to help create that “creamy” taste.

A sauce can taste “creamy” without actually containing cream.

27

To say a food tastes “light and crispy” is to make a judgment about mouthfeel.

Packaging can change the perception of a food’s “crispiness.” Studies suggest that people biting into potato chips (Pringles) rate the chips as 15% fresher when the sounds are louder, or when the high frequency components of the biting sounds (above 2KHz) are boosted.

Other studies show we judge food in noisy packages to be crisper than the same foods in “quiet” packages.

28

We love the mouthfeel of fatty foods. Fat gives food a pleasing “body,” and contributes to a sense of fullness in the mouth.

We don’t eat over twenty-eight pounds of french fries per person each year because we love the taste of potatoes. We eat fries, fish sticks, onion rings, doughnuts, chicken nuggets, and potato chips because their high fat content makes them feel good in the mouth. They are sensation-filled.

29

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

30

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 will trigger a taste sensation in about half the people.

Warming an apple pie can create the perception of a sweeter pie.

31

But letting ice cream melt completely leaves it tasting like overly sweet milk.

Taste tests in which participants are asked to judge liquids need careful controls for temperature. The warmer liquid will taste a bit sweeter. There might be more taste difference between a warm Coke and cold one than between a Coke and a Pepsi served at the same temperature.

32

We call spicy foods “hot,” but not because of temperature. The heat we feel from spicy food is not a message from our taste buds. Some spices activate our pain receptors. We “feel” the pain of spice as heat and treat it as part of the taste multi-sense.

Capsaicin--the chemical found in chili peppers--produces the illusion of heat. It might be more accurate to say foods “feel” spicy than that they “taste” spicy.

33

Menthol triggers cold receptors in the mouth to create the very real illusion of coolness.

Neither menthol nor capsaicin actually changes skin temperature even though they feel warm and cool.

Menthol is made synthetically or obtained from peppermint or other mint oils.

34

Think about spicy foods you’ve eaten and you might recognize two distinct varieties: one you feel in your mouth and the other in your nose.

The molecules in chilies and black peppers are large and heavy – they tend not to escape up our nose – we “taste” them mainly in the mouth.

Mustard plants (that includes horseradish and wasabi) release a small molecule when the plant is damaged (sort of like the plant version of a skunk), so it easily escapes from the food and enters the nose.

So you sense a jalapeno in the mouth and wasabi in the nose but you call both “spicy” or “hot.”

35

4. Tasting Expectations

Taste is chemistry.

Flavor is psychology.

We taste our beliefs and

expectations.

36

MIT psychologists conducted a taste experiment in which they asked bar patrons to taste a beer they called “MIT brew” – regular beer with a few drops of balsamic vinegar. In blind taste tests, people preferred the altered beer.

The experiment used two groups of tasters – one was told about the vinegar BEFORE they drank the beer, the other group learned about the vinegar only AFTER the taste test.

Those who knew about the vinegar flavoring rated the beer much worse than those who learned only after drinking. The belief that vinegar and beer don’t mix shaped the drinker’s taste perception.

37

One study asked people to rate the taste of plain Seltzer water and Perrier. Researchers found that people preferred the Perrier when the waters were labeled, but showed no clear preference when the labels were removed.

38

Other researchers found strawberry yogurt and cheese spreads are rated as less tasty when 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.

39

At the Center for Theoretical Neuroscience at Baylor College of Medicine , sixty-seven people tried a blind taste test of Coca-Cola and Pepsi. About half chose Coke and half Pepsi.

But when the subjects were told they were drinking Coke, over 70% said Coke tasted better. Magnetic imaging of their brans showed that when the tasters knew they were drinking Coke they used brain areas relating to memories and impressions that were not used during the blind taste tests.

The results suggest that the preference for a favored brand (Coke, in this case) is shaped by memories and expectations .

40

In 1985, Coca-Cola attempted to introduce a “new and improved” Coca-Cola. Using nationwide blind taste tests they found that people liked the slightly tweaked “new Coke” better than both the “old” Coke and Pepsi.

But after rolling out the “New Coke,” people stubbornly insisted they preferred the “old” taste. Blind taste tests do not mimic real life. In a lab, tasters judge by taste. In the real 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.

41

One clever study asked children to rate the taste of carrots, milk, and apple juice. In one group, the foods were served in unmarked wrappers. In the other, the same foods were wrapped in McDonald's packaging. The unmarked foods always lost the taste test.

Study author Dr. Tom Robinson noted their perception of taste was "physically altered by the branding. Kids don’t just ask for food from McDonald’s, they actually believe that the chicken nugget they think is from McDonald’s tastes better than an identical, unbranded nugget.”

42

Researchers at Stanford and Cal Tech had people sip wine while an fMRI machine measured brain activity.

Volunteers sipped various wines including the same red wine twice. For one tasting, volunteers were told the wine sold for $5 a bottle (the actual price), but the second time they were told it was a $45 wine. The subjects said they liked the expensive wine better.

The increased preference was seen as increased activity in the prefrontal cortex. The subjects really did enjoy the expensive wine more.

43

A study gave consumers a choice among three jars of peanut butter. In a blind taste test, one brand won “best tasting” 60% of the time -- a clear winner.

Next, researchers tested the same choices but with labels on the jars. One label was a well-known, heavily-advertised national brand, while the other two were unknown brands. In this test, the peanut butter that won the original taste test was in a jar with an unfamiliar label. Would it still win the taste test?

Nope. This time, 73% chose the lower-quality spread with the well-known brand name. Only 20% chose the high-quality product in the unfamiliar jar.

44

Psychologists use the term “expectation bias” to describe our tendency to taste, hear, and see what we expect.

The orange juice really will taste better if it is bright orange, the wine will taste more full-bodied and complex if it costs more. The Coca-Cola and peanut butter will taste worse from an unlabeled source than from one marked with a familiar brand, and kids will find that apples taste better if they come from a bag with the McDonald’s logo. We see, hear, taste, and feel our expectations.

45

5. Culture shapes tastes

We define ourselves in part by what we taste. People who eat like us are probably “Us” while those who eat strange and disgusting foods are clearly “Them.”

By the time we reach age eight our culture has shaped our tastes. But culture to the individual is like water to a fish. We see cultural differences in others easily, but the influence of our own culture often remains invisible. We feel a bit uneasy in the presence of people who eat things we do not consider food.

We spend millions to buy food for cats, dogs, and horses but consider it nearly inhuman to buy cats, dogs, and horses for food.

 

Ground horsemeat

Cooked dog

46

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 of 1876, curious fair goers could try a banana wrapped in tinfoil for ten cents. It was quite a novelty.

Milk has long been viewed as a dangerous food.

47

Four and twenty blackbirds baked in a pie is not merely a line in a nursery rhyme – it’s a recipe.

Blackbird pie? Did people really eat song birds. Yes. To discover why we eat mostly chicken and ignore most other birds requires a bit of history.

48

Many cultures eat all sorts of small birds. A bird on a stick is common street food in China.

Surprisingly, chicken as an ordinary food is a relatively modern idea.

49

In 18th and 19th century America, dining on a bird meant a young pigeon. These “squabs” were not the pigeons we see in today’s urban downtowns, nor were they carrier or homing pigeons used as our first airmail.

They were a completely different species – a wild bird called the passenger pigeon, named after the French word for “passage” meaning migratory. Their numbers during migration hundreds of years ago strains the belief of today’s urban dwellers.

50

A flock of passenger pigeons could darken a Midwestern sky for most of a day. The flocks were so thick that a single shotgun shot could bring down thirty or forty birds. Many were killed simply by swatting at them with wooden bats as they flew over hilltops or by stringing nets.

51

When Europeans first arrived in North America, they shared the “new world” with about five BILLION passenger pigeons – a number nearly equal to the total of ALL birds today in the United States. Fast growing east coast cities needed food and passenger pigeons made for a convenient supply. On just one day in 1860, over 235,000 birds were sent east from Grand Rapids, Michigan. In 1869, Van Buren County, Michigan shipped seven million, five hundred thousand birds back east. If drive-up windows existed in the 19th century, they would have offered fried squab, pigeon nuggets, and songbird stew.

52

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 Passenger Pigeon was nicknamed “Martha” after Martha Washington and died in 1914 in the Cincinnati zoo.

53

We didn’t we eat lots of chicken before the 1950s because chickens were more valuable for their eggs. A good eating chicken was a seasonal luxury costing as much per pound as a good steak.

The USDA and meat producers eventually learned how to produce a tasty and reasonably priced chicken – but only after years of breeding trials and errors. These “chickens of tomorrow” had more meat, larger breasts, and thicker legs than their scrawny ancestors.

54

Only with the advent of mass scale processing in the 1950s did chicken become a constant presence on our culture’s unwritten menu. In 1945, per capita chicken consumption was only five pounds yearly, by 1960 it was over 25 pounds.

The taste of today’s chicken would be unfamiliar to most of our great grandparents. The taste of a culture can change with time.

 

55

6. How do we taste?

The function of taste and smell is to detect chemicals. We speak of 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

56

The actual organ of taste is called the "taste bud." Each taste bud (you have nine or ten thousand in your mouth) contains between fifty and one hundred fifty receptor cells. Receptor cells live for only a week or two before they are replaced by new ones.

Each receptor in a taste bud responds best to one of the five basic tastes: salty, sweet, sour, bitter, and savory.

57

SavorySavory (often called by its Japanese name umami) is triggered by the amino acids glutamate and aspartate in cheeses, mushrooms, some vegetables, meats, and MSG. Umami is a pleasant “brothy” or “meaty” taste. It was recognized as a basic taste only in 1985.

Our first experience with umami is breast milk. It contains about the same amount of umami as broth.

Glutamate is naturally present in a many foods, especially mushrooms, beef, cabbage, and tomatoes. A pizza (tomato sauce, sausage, cheese, mushrooms) is high in glutamate content. It’s very savory.

58

Sweetness signals easy calories – fast energy. We are genetically predisposed to seek sweetness -- it’s not a result of poor parenting. You can detect sweetness if only one part in two hundred is sweet – that’s about one teaspoon of sugar in two gallons of water.

Sweet

59

Today, about a third of the world's 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.

60

But if you grew up after the mid 80s, you probably ate more sugar from corn. Beginning in 1980, large beverage companies began using corn syrup to sweeten soft drinks.  Today, corn sweetener is widely used in foods and beverages. Look on ingredient lists for corn syrup, corn sugar, or high fructose corn syrup – sometimes shortened to HFCS.

61

Many believe cane sugar tastes better than corn sweetener. Yet blind taste tests usually show no clear preference. But remember that taste is not merely about detecting molecules. Flavor is a perception based on our beliefs and expectations. If we believe “natural," or “organic,” or “cane sugar” is better, it will taste better

Some beverage makers replaced corn syrup with cane or beet sugar (sucrose) and explained the change as about “delivering great taste.”

Kosher Coca-Cola does not contain HFCS.

62

Salty

Babies show a preference for salty water – humans need salt to live. Blood, sweat, and tears are all salty. Blood holds about as much salt as ocean water.

We can taste salt in water at a concentration of a teaspoon in ten quarts. Salt sensitivitydeclines with age. At age60, double that con-centration is needed to be tasted.

Almost every fluid in your body contains salt. Your body holds about seven tablespoons of salt.* You lose salt constantly and cannot store it, so you need salt every day.

63

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

64

Sour

What we call a “sour” taste is our ability to sense acidity.

We need to sense sour to keep us away from foods that might upset our body chemistry and destroy cells in our gut. The abilities to taste both bitter and sour seem clearly protective strengths.

Tasting acidity also helps us judge the ripeness of food. Fruit, for example is less nutritious sour than when sweet.

65

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.

66

People vary in their ability to taste. One in four is a “supertaster.” Supertasters have more taste buds per square centimeter. About 25% are non-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 to smoke because of the bitter taste of nicotine, and avoid the bitter taste of caffeine in coffee or blunt it with cream and/or sugar. Non-tasters find tastes less intense. They are often easier to please in food choices.

67

The sense of smell accounts for as much as 80% of flavor.

Without a sense of smell you would find it difficult to tell the difference between coffee or tea, red or white wine, grated apple and grated onion. Our sense of smell makes an apple taste like an apple rather than a pear or turnip. If your smell is impaired (by a cold, for example), food tastes bland, but you can still sense the four basic tastes. You could sense a jelly candy is sweet, but you could probably not tell lemon from orange.

68

You think of smell as entering your nose from the outside – sniffing the air.

But most of the odor involved in tasting works from the inside out – it’s called retronasal odor. Odors enter your nasal passage through the back of your mouth and rides the air you exhale or swallow. You don’t consciously inhale these odors, so you do not experience them as smells – they are simply part of the flavor.

69

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

70

If we taste what we expect, what is the effect of growing up eating so many foods with artificial colors and flavors? Do kids learn from experience that “orange” is the taste of a frozen orange dessert, and cherry that sweet flavor found in bottles of red juices?

Could kids today grow up never learning what a real orange or cherry tastes 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 is unfamiliar and contrary to expectations?

After all, what tastes best is what you’re used to, even if it comes from a factory instead of a farm.

71

The End