|Why Humans Like Junk Food
The Inside Story on Why You Like Your Favorite Foods, the Cuisine Secrets of Top Chefs, and How to Improve Your Own Cooking Without a Recipe!
Steven A. Witherly, PhD
iUniverse Inc. Publishing
Lincoln, NE 68512
Disclaimer: The information, ideas, and suggestions in this book are not intended as a substitute for professional medical advice. Before following any suggestions contained in this book, you should consult your personal physician. Neither the author nor the publisher shall be liable or responsible for any loss or damage allegedly arising as a consequence of your use or application of any information or suggestions in this book.
Excerpted from The French Laundry
Copyright © 1999 by Thomas Keller
Copyright © 2004 by Thomas Keller
Used by Permission of Artisan, a division of Workman Publishing Co., New York
All Rights Reserved
Excerpted from Les Halles Cookbook
Copyright © 2004 by Anthony Bourdain
The Nasty Bits
Copyright © 2006
Reprinted by permission of Bloomsbury USA
Scripture taken from the NEW AMERICAN STANDARD BIBLE
Copyright © 1977 by The Lockman Foundation. Used by permission
Fundamental Principles of Food Perception and Pleasure
Chapter 1: Food Pleasure Theories and Principles
The Stomach: the Second “Taste” System
Glossary of Terms Used
Why We Like Our Favorite Foods
Chapter 2: Why We Like Corn Tortilla Chips
Chapter 3: Why We Like Sandwich Cookies
Chapter 4: Why We Like Vanilla Ice Cream
Chapter 5: Why We Like Butter
Chapter 6: Why We Like Gourmet Coffee
Chapter 7: Why We Like Popcorn
Chapter 8: Why We Like Donuts
Chapter 9: Why We Like Garlic
Chapter 10: Why We Like Toasty Sandwiches
Chapter 11: Why We Like Hamburgers
Chapter 12: Why We Like Southern Fried Chicken
Chapter 13: Why We Like Diet Vanilla Soda
Chapter 14: Why We Like French Fries
Chapter 15: Why We Like Spices
Chapter 16: Why We Like Chocolate
Chapter 17: Why We Like Artichokes
Chapter 18: Why We Like Pizza
Chapter 19: Why We Like To Eat Dessert Last
Secrets of Great Cooking and Cuisine Design
Chapter 20: Secret-Weapon Pleasure Foods
Chapter 21: Culinary Secrets of the Top Chefs
Chapter 22: Eight Most Common Cooking Mistakes
Chapter 23: Tasty Home Cooking and Healthy Fast Food: a Summary
Appendix A: Cooking Resources
About the Author
First, I dedicate this book to my wife, Caroline, and our dear little daughter Clarissa (sweet pea). Caroline convinced me that I must finish this work and assisted in proofing and designing the look and contents. Clarissa managed to keep busy—with her many friends and playthings—to allow me time to write. And I hope my two sons, Eric and Ryan, both of whom like to cook, will find this work at least a little interesting. (Hey guys, I finished it!)
Second, I must remember and thank my mentor and sensory sciences professor, Rose Marie Pangborn, for encouraging me to think outside the physiological box on food palatability and pleasure. Without her support and helpful guidance I would never have come this far in explaining the surprisingly complex world of food perception. Cancer ended the life of this great researcher, and I keep her in my prayers.
Third, I must thank my good friend Dr. Bob Hyde (professor at San Jose State University), whose natural genius in solving scientific riddles formed the basis of many of the theories herein. And to think it all started with a casual chat in my kitchen back in 1986, while we both sipped merlot (yes, that’s right, merlot—way before the popular movie Sideways).
I’d also like to thank Mike Dauria, Nestlé Foods, for his helpful editorial comments; Bruce Horovitz (USA Today staff writer) for his inspirational idea of the food diagrams; the Restaurant Guys (restaurantguysradio.com), Francis Schott and Mark Pascal, for their kind comments on the rough draft of this book; and Uberchefs Thomas Keller and Anthony Bourdain, whose cookbooks and keen insights into culinology were a personal inspiration. Mr. Bourdain’s entertaining quotes are reprinted by permission of Bloomsbury USA. And the culinary wisdom of Keller is quoted by permission of Artisan, A Division of Workman Publishing Company, Inc., New York. Finally, scripture quotes are taken from the New American Standard Bible, Copyright 1995 by the Lockman Foundation.
This work is also a reflection and, in a sense, a culmination of the genius of many researchers in food perception and sensory science. In the past, I have recognized their contributions by naming some food perception phenomena after these researchers’ last names. While this is unconventional in science, it is a simple way to remember some of the more important food principles. I have tried to the best of my ability, using the wisdom and insight from the scientific literature, to explain and simplify the many food phenomena and behaviors.
I would like to mention just a few of the names of those great scientists whose work is both illuminating and inspirational.
Gary Beauchamp David Booth David Wingate
Thomas Scott Barbara Rolls Dana Small
Edmund Rolls L. L. Birch Morley Kare
Anthony Sclafani Harry Kissileff Patricia Pliner
Elizabeth Capaldi Jacques Le Magnen Ilene Bernstein
Rose Marie Pangborn Leann Birch Ann. C. Noble
Linda Bartoshuk Paul Rozin Eric Block
Michel Cabanac Adam Drewnowski Patricia Pliner
John Blundell Kent Berridge L. Wisniewski
Mark Fantino Marion Hetherington Robert Hyde
Susan Schiffman Harold McGee Louis J. Minor
Thomas Scott Rachel Schemmel Gilbert Leveille
Julia Child Emeril Lagasse David Mela
Ernie Strapazon Dale Romsos Morten Kringelbach
Ted Williams A. W. Logue Michael O’Mahony
Alton Brown Martin Yan C. Broberger
And there are many others …
The reader can learn much by Googling these names and reading their many interesting papers. To this day, I am amazed that their works have not received the general recognition they deserve—after all, food scientists, chefs, and the home cook would greatly benefit by an understanding of food perception and the pleasures of the palate!
To the Reader:
In this book, I have tried to simplify and outline the various food pleasure principles as much as possible in general observations, aphorisms, and theories; I’ve often used bullet points in a teaching manner.
To the Dietitian: I would hope these principles may be used to make healthy food taste good. It is certainly possible! Pleasure is the major driver of food ingestion and behavior, but without an understanding of the nature of food pleasure and perception itself, no useful modifications to food can be made. Salt, fat, and sugar, classically considered a nutritional enemy, can still be used for good.
To the Food Scientist: Sadly, the principles of good food construction are not part of any food-science curriculum that I am aware of—probably because of the sheer complexity of the subject and the lack of physiological training in the food sciences. This book, then, may be your first exposure to the interrelated world of food physiology, psychology, and neuroscience. In your profession, you create foods that millions eat; use these principles to elevate your own understanding of good food construction.
To the Professional Chef: Many excellent chefs use the principles described in this book without actually knowing it; they use tradition, training, and talent in their food design. Hopefully, I will demystify what you may already know. The time-honored principles of French cooking were actually the impetus behind my scientific investigation of the “why” of classic cuisine, which was presented at the 1985 Geneva nutritional conference and published in the 1986 book: Food Acceptance and Nutrition titled: “Physiological and nutritional influences on cuisine and product development.” Twenty years later, food intake and neuroimaging research coupled with advances in taste and smell perception have completely transformed the fields of food science and sensory perception.
“Nothing would be more tiresome than eating and drinking if God had not made them a pleasure as well as a necessity.”
Final Note: Any errors in punctuation, syntax, or grammatical correctness are mine alone—blame them on Sentence Specific Satiety.
Chapter 1: Food Pleasure Theories and Principles
The brain’s pleasure centers prefer salt, sugar, and fat mixtures.1,2,3
All of our favorite foods have unknown physiological and neurobiological explanations as to why we prefer them and why they have endured as best sellers over the years. In fact, I started studying the psychobiology of the popular snack food Doritos in an effort to understand why this billion-dollar brand is a huge success year after year in the United States—and many foreign countries as well. I studied the food intake and chemical senses literature—over five hundred research reports and four thousand abstracts—in order to discern the popularity of Doritos. In the process I developed the Food Pleasure Equation (Capaldi-inspired) and, in collaboration with Dr. Robert Hyde (San Jose State University), the important theory of Dynamic Contrast in foods.
There are hundreds of food palatability theories and influences (and seemingly endless neurotransmitters, neuropeptides, and hormone effectors). The list we will discuss includes what I think are the most important and useful food perception theories. In my evaluation process I used the philosophy of the renowned physicist Albert Einstein, who once said (I paraphrase) that a good theory must have three properties: it should explain the phenomenon, it must predict future behavior of the phenomenon, and it must be simple, the simpler the better—but not any more than that. It is the hope of this author that the principles enumerated below will help explain why you eat what you eat (food enlightenment), elevate your own cooking prowess (it’s fun to prepare meals for your friends), and perhaps even make good-for-you food tasty and delicious. Please note that not all researchers will agree with my list, and some may not even want to be associated with the phenomenon—but after twenty years of giving lectures and talks, I think it is both honorable and heuristic to put names behind the science.
In 1825, a French lawyer, Jean Anthelme Brillat-Savarin, wrote a brilliant treatise on food and philosophy called the Physiologie du Goût. Quite ahead of its time, and still quoted today, The Physiology of Taste contains insights and musings on the sense of taste, food pleasure, gastronomy, coffee, chocolate, and even the first description of the “umami” taste of MSG (called the osmazome). I found his work inspiring (see my chapter on chefs), and I have tried to update his treatise with this current work using the very latest research in food science and neurophysiology—just as he predicted in the first chapter of his book. For a complete copy of his work on the Web, see http://etext.library.adelaide.edu.au/b/Brillat-Savarin/savarin/b85p/.
The following is a list of the most important food palatability theories of particular interest to food scientists, chefs, dietitians, and those who just like to cook. This is not in order of importance, but merely a listing. I selected these sixteen theories from over a hundred published food-perception phenomena in the scientific literature. I believe they explain most of the food behavior we see in our daily life.
Major Food Perception Theories
Food Pleasure Equation (Hyde/Witherly)
Sensation Plus Calories
Dynamic Contrast (Hyde/Witherly)
Ping-Pong Pleasure Contrast (Hyde)
Tostada Effect (Witherly)
Meatloaf Effect (Witherly)
Sensory Specific Satiety (Rolls) or “Variety Effect”
Supernormal Stimulus (E. O. Wilson)
Evoked Qualities (Hyde) a/k/a Emeril “BAM!” Effect
Flavor-Flavor Learning (Pliner)
Mere Exposure Effect (Pliner)
Taste-Aversion Learning (Bernstein/Rozin)
P. Rozin’s Principles of Food Likes and Dislikes
E. Rozin’s Flavor Principles
Energy Density Theory (Drewnowski)
Vanishing Caloric Density (Hyde)
Post-Ingestional Conditioning (Booth, Capaldi)
Human “Cookivore” Theory (Wrangham)
Aroma and Essential-Nutrient Encoding (Goff and Klee)
“Liking” Versus “Wanting” Theory
The Stomach: the Second “Taste” System
Six Most Important Food Theories:
Taste Hedonics (salt, sugar, and umami)
Dynamic Contrast (food arousal and surprise)
Evoked Qualities (when food sensory properties evoke past memories)
Food Pleasure Equation (Food Pleasure = sensation + macronutrients)
Caloric Density (humans like food with a CD of about 5.0)
Emulsion Theory (taste buds love foods in emulsified forms)
Food Perception Theories
The reality is that scientists know very little about food choice or preference.4 Food pleasure appears to involve both the opioid and cannabinoids reward circuitry that interact in complex ways.5 Moreover, if we wish to understand the nature of overeating and obesity we must explore the science behind what makes food taste good.6
1. The Food Pleasure Equation
“O taste and see that the Lord is good.”
Psalms 34:8 (NASB)
“You are the salt of the earth; but if the salt has become tasteless, how will it be made salty again?”
Matthew 5:13 (NASB)
Food Pleasure = Sensation (Taste, Aroma, Orosensation) + Calories (Macronutrients)
Sensation plus Caloric Stimulation
Amino acid stimulation
Vanishing Caloric Density (Hyde)
Food pleasure is a combination of sensory factors (sensation) and caloric stimulation by the macronutrients (protein, carbohydrate, and fat). Sensory factors that most contribute to pleasure are salty taste, sweet taste, umami taste, and orosensation from the oral cavity (feeling). Aroma is important in food discrimination but not a primary hedonic driver like taste. Dynamic Contrast in the food plays a major role in food pleasure (texture and taste contrasts, food meltdown, and temperature changes).
The body regulates all three macronutrients with intricate feedback mechanisms—but uses the total amount of calories as the general sensor. And as we will learn, high caloric density foods are preferred over lower—brain scans show a reduced hedonic response when subjects view a plate of vegetables versus a higher calorie alternative. Depressing, isn’t it?
The Food Pleasure Equation postulates that the brain has the ability to quantify the pleasure contained in an eating experience as performed by certain dopamine neurons in the brain and the sensing of calories by the gut. When you have a food choice, the brain actually calculates how much pleasure will be generated during the eating and digestion of a particular food. The goal of the brain, gut, and fat cell is to maximize the pleasure extracted from the environment, both in food sensation and macronutrient content. If a food is lowered in calories for health reasons, the gut has the ability to sense this, and the food will become less palatable over time (think frozen yogurt or light potato chips). To keep the food pleasure elevated, one must add additional sensation, e.g., more taste, greater dynamic contrast, or added orosensation. The biggest mistake I see in the commercial marketplace is creating a light food (that tastes and looks exactly like the original) without adding more pleasure sensation(s). Given the choice of two foods exactly alike in sensory terms, the brain, with instructions from the gut and fat cell, will always choose the higher-calorie original.
B. Taste Hedonics
As mentioned above, certain solutes (salt, sugar, MSG, and the 5’-nucleotides in solution) in foods contribute most to food pleasure. In numerous studies, we find that the taste of sugar, particularly sucrose, and salt drive taste hedonics and ingestion. Monosodium glutamate (MSG) taste, or “umami,” is now firmly entrenched as the fifth hedonic taste. Umami means “deliciousness” in Japanese and is believed to signal the presence of protein in your mouth. Protein, by itself, does not have much taste (try chewing on a raw steak if you are a skeptic). MSG, interestingly, does not have that much taste on its own either; kind of brothy and a little salty, but add sodium chloride to it, and the hedonic flavors just explode!
C. Emulsion Theory
Taste buds (and higher-order brain structures) like the taste of emulsions, whether they are salt-fat or sugar-fat combinations. The most agréable foods are true emulsions, whether they are butter, chocolate, salad dressings, ice cream, hollandaise sauce, mayonnaise, or crème. One major reason for this is the concentration effect of the hedonic taste solutes when made into an emulsion. For example, butter is about 2.5 percent salt by weight, but this level of salt is concentrated into the 15 percent water phase of the butter emulsion. In effect, the true salt concentration is 10 percent—a true hedonic salt rush.
French chefs are masters of emulsion creation, and the humble mashed potato is no exception. In the French Laundry Cookbook (p. 86), Thomas Keller describes the exacting technique of using a chinois (cone strainer) to create the perfect emulsification of potatoes, butter, and cream—or pomme purée. Chef Rowley Leigh, food columnist for the Financial Times USA, writes about the extraordinary (unctuous) mashed potatoes of French chef Joel Robuchon—finest ratte waxy potatoes emulsified with equal parts of unsalted Normandy butter.7
D. Salivation Response
My salivation theory states that we prefer foods that are moist or evoke saliva during the mastication process. Saliva is critical for hedonic solute contact with taste buds; simply put, no taste, no pleasure. Saliva also fosters food lubrication and enhances the entire eating experience. Even dry foods like saltines have salt on top and a flaky texture that fosters salivation as it melts down in the mouth. Add fat to a dry food (potato chips are 50 percent fat calories), and you have additional oral lubrication—the perfect “salivation” food. Thin potato chips have a texture that melts down very quickly and stimulates salivary flow. The tastiest foods should evoke saliva or at least provide lubrication and moistness. Culinologists and great chefs know this secret. French chefs are masters of food saucing; Chinese (and Asian food in general) and Indian cuisines are almost entirely finished with a sauce or glaze.
We have all experienced “mouth watering” when presented with tasty food, especially when we are hungry. Salivation is tied into the whole experience of eating. And Temple et al. (2006) found that as we eat more of the same food, we secrete less saliva—we are actually habituating to the food in a manner similar to Sensory Specific Satiety.8 This amazing response actually means the food becomes less pleasurable as you continue to eat it, and you salivate less! Taken to another level, this means that superior cuisine that keeps you stimulated with texture, colors, and taste will not allow this salivation habituation response to occur. In fact, salivation to a food may be an independent measurement of how much you like it. (Dr. Robert Hyde and I performed a number of salivation experiments under the direction of Professor Rose Marie Pangborn at UC Davis.)
2. Dynamic Contrast (DC)
“So because you are lukewarm, and neither hot nor cold, I will spit you out of My mouth.”
Revelation 3:16 (NASB)
The Witherly and Hyde theory of DC states that people prefer foods with sensory contrasts—light and dark, sweet and salty, rapid meltdown in the mouth, crunchy with silky, and so on. Temperature changes in the mouth are also highly arousing and pleasurable. “Ping-Pong Pleasure” refers to an ingestion pattern, in which people tend to alternate between foods that cleanse the palate, like drinking beer (which is low sodium) with salty snacks, or wine with food (wine is very low sodium and acidic). Studies indicate that the brain has a craving for novelty, which produces a “thrilling effect” via the release of brain opioids (endorphins).9 In fact, we used to call our theory “dynamic novelty,” wherein the mouth delights in texture, flavor, and orosensory novelty. In 2006, Biederman and Vessel proposed that humans are “infovores”; where pleasure systems (using mu-opioids) actually guide human behavior for learning (and preference for novelty) in a constantly changing or challenging environment—hence, the addictiveness of video and Internet gaming.9 In the same way, gustation and orosensation excite mu-opioids in the medial and forebrain sections (our pleasure centers), guiding our pleasures of ingestion.
Many foods with high DC have the same feature, which I call the Tostada Effect—an edible shell that goes crunch followed by something soft or creamy and full of taste-active compounds. This rule applies to a variety of our favorite food structures—the caramelized top of a crème brûlée, a slice of pizza, or an Oreo cookie—the brain finds crunching through something like this very novel and thrilling. No doubt, higher-order brain mechanisms release opioids—and probably a separate population of neurons distinct from the activation of the classic taste centers. This phenomenon name is derived from the only dish that I cooked in college that was popular with my roommates—sometimes we would eat it once a week. (Cooking the tostada shells can be hazardous; one roommate, while trying to deep-fry the corn tortilla, ignited the paper-towel rack with the hot oil. A well-aimed dousing with beer saved the apartment.)
The exact opposite of adding contrasting flavors, textures, and tastes is what I call the “meatloaf effect”, affectionately named after this most quintessential American dish that evokes sensory yawns and feelings of apathy—a taste bud dud. Top French chefs know this effect well and take great lengths to reduce or eliminate it entirely. Thomas Keller is one of the best at this—he crafted the French Laundry and Bouchon Cookbook recipes to eliminate the accidental blurring of sensation and diminution of pleasure. (See my chapter on secrets of the chefs). The meatloaf effect is very prominent in canned foods or in stews and soups that sit around for a long period. The intense heating called retort processing or, to a lesser extent, aseptic processing, transforms fresh and bright looking ingredients into muted colors and unidentifiable flavors. Not only does the meatloaf effect reduce food pleasure, but consuming such foods creates a bad-food memory complex. To this day, the taste and smell of a tinny, canned vegetable evokes the sensory shudders of my youth. Julia Child writes of this effect as well and provides culinary guidance on how to eliminate it.10 She describes culinary techniques that transform ordinary canned beef bouillon into a tasty brown sauce. I often use Thomas Keller’s favorite (fresh thyme and bay leaf) flavoring complex to revitalize sauces that use canned chicken or beef broths.
3. Sensory Specific Satiety (SSS)
SSS is a very important theory in food pleasure appreciation. It states that as we eat food, the pleasure response to the sensory properties of the food decreases within minutes. This involves parts of the brain (orbitofrontal cortex) that sense the taste, aroma, texture, and even visual aspects of foods.11 A decrease in pleasure response is the body’s way of encouraging the intake of a wide variety of foods—differing in flavors and textures. The opposite or reciprocal of SSS has been called the “variety effect” or the “smorgasbord effect,” wherein we eat more when presented with food variety. The SSS effect is quite rapid (as little as ten minutes) and has culinary implications for creating the most interesting and pleasurable food. Thomas Keller (of French Laundry fame), understands this effect, he calls it the law of diminishing returns, and specifically designs his tasting courses to counteract this negative effect on food pleasure.12
4. Super Normal Stimulus or Super Size Me
This is a long-held biology principle stating that rare and important stimuli in the environment (like energy-dense foods) become magnified and more desirable (or Super Normal) if made larger than expected—like a supersized order of French fries or the 1,400 kcal Monster Thickburger. Meat is a valuable and precious macronutrient in our evolutionary past, and half a heifer on a bun is visually exciting and stimulates the overall ingestive response. Several studies indicate that big portions excite the palate, and people just eat more. Although the super size phenomenon is waning, big portions are still the norm in many restaurants. Many of our favorite foods are supernormal combinations of salt, fat, and sugar that exceed anything available to our wandering ancestors. We evolved to crave these valuable and rare nutrients. Hence, we respond with an exaggerated eating response (hyperphagia) to the super normal sundae.
Super normal stimuli exist in other avenues, such as the entertainment world. The cartoon drawing of Jessica Rabbit (from the movie Who Framed Roger Rabbit) and, to a more limited extent, Barbie, are popular examples of obvious accentuation of physical attributes beyond normal physiological probability, with the intent of enhancing female desirability. For a discussion on this phenomenon, see E. O. Wilson’s book Consilience: The Unity of Knowledge.
Brian Wansink, marketing professor at Cornell and author of Mindless Eating, has studied this phenomenon and found that portion size can even supersede taste as a driver of ingestion.13 Similar to the supersize phenomenon in fast food, he found moviegoers given popcorn in large buckets ate 34 percent more. I can’t wait to read his book.
5. Evoked Qualities (EQ)
Dr. Robert Hyde’s hypothesis states that the act of eating food creates memories, not only the sensory properties of that food, but the event of eating, and even the people you ate with. This food-environmental experience creates a permanent memory engram. Later on, this memory can be “evoked” or relived by exposure to the sensory properties of the food or one’s mere presence in the same environment. Food cravings are often triggered by sight, smell, and caloric memories of restaurants past. One EQ example is Emeril’s ubiquitous use of his excellent “Original Essence” seasoning—or “BAM!” spice blend. It contains a number of culinary spices (onion, garlic, Italian herbs) whose aromas evoke past memories of food ingestion and happy times. And, according to the theory, one does not need to be consciously aware of the underlying memories being recalled. Neuroscientist Sarah Leibowitz has also noted that every food experience creates a sensory memory response to the food, the caloric level, and the social surroundings.14 Another example is Chef Thomas Keller, who reminisced that every time he prepares onion soup it brings back memories of every bowl of soup he has ever consumed.12